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} .loading { visibility: hidden; } .detail-page .post-footer .cmt_iframe_holder { padding-top: 40px !important; } /** Desktop **/ @media (max-width: 900px) { .col-right { display: none; } .col-main { margin-right: 0; min-width: initial; } .footer-outer { display: none; } .cols-wrapper { min-width: initial; } .google-footer-outer { background-color: #f5f5f5; } } /** Tablet **/ @media (max-width: 712px) { .header-outer, .cols-wrapper, .footer-outer, .google-footer-outer { padding: 0 40px; } } /* An extra breakpoint accommodating for long blog titles. */ @media (max-width: 600px) { .header-left { height: 100%; top: inherit; margin-top: 0; -webkit-transform: initial; transform: initial; } .header-title { margin-top: 18px; } .header-inner .google-logo { height: 40px; margin-top: 3px; } .header-inner .google-logo img { height: 42px; } .header-title h2 { font-size: 32px; line-height: 40px; } .header-desc { bottom: 24px; position: absolute; } } /** Mobile/small desktop window; also landscape. **/ @media (max-width: 480px), (max-height: 480px) { .header-outer, .cols-wrapper, .footer-outer, .google-footer-outer { padding: 0 16px; 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} /** List page tweaks. **/ .list-page .post-original { display: none; } .list-page .post-summary { display: block; } .list-page .comment-container { display: none; } .list-page #blog-pager { padding-top: 0; border: 0; margin-top: -8px; } .list-page .label-footer { display: none; } .list-page #main .post .post-footer { border-bottom: 1px solid #eee; margin: -16px 0 0 0; padding: 0 0 20px 0; } .list-page .post .share { display: none; } /** Detail page tweaks. **/ .detail-page .post-footer .cmt_iframe_holder { padding-top: 32px !important; } .detail-page .label-footer { margin-bottom: 0; } .detail-page #main .post .post-footer { padding-bottom: 0; } .detail-page #comments { display: none; } } [data-about-pullquote], [data-is-preview], [data-about-syndication] { display: none; } </style> <noscript> <style> .loading { visibility: visible }</style> </noscript>  <script async='true' src='https://www.googletagmanager.com/gtag/js?id=G-K46T604G22'></script> <script> window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-K46T604G22'); </script> <link href='https://www.blogger.com/dyn-css/authorization.css?targetBlogID=1176949257541686127&zx=3087bdcb-1962-4cce-ae50-737c70a68c4e' media='none' onload='if(media!='all')media='all'' rel='stylesheet'/><noscript><link href='https://www.blogger.com/dyn-css/authorization.css?targetBlogID=1176949257541686127&zx=3087bdcb-1962-4cce-ae50-737c70a68c4e' rel='stylesheet'/></noscript> <meta name='google-adsense-platform-account' content='ca-host-pub-1556223355139109'/> <meta name='google-adsense-platform-domain' content='blogspot.com'/> </head> <body> <script type='text/javascript'> //<![CDATA[ var axel = Math.random() + ""; var a = axel * 10000000000000; document.write('<iframe src="https://2542116.fls.doubleclick.net/activityi;src=2542116;type=gblog;cat=googl0;ord=ord=' + a + '?" width="1" height="1" frameborder="0" style="display:none"></iframe>'); //]]> </script> <noscript> <img alt='' height='1' src='https://ad.doubleclick.net/ddm/activity/src=2542116;type=gblog;cat=googl0;ord=1?' width='1'/> </noscript>  <div class='header-outer'> <div class='header-inner'> <div class='section' id='header'><div class='widget Header' data-version='1' id='Header1'> <div class='header-left'> <div class='header-title'> <a class='google-logo' href='https://security.googleblog.com/'> <img height='50' src='https://www.gstatic.com/images/branding/googlelogo/2x/googlelogo_color_150x54dp.png'/> </a> <a href='/.'> <h2> Security Blog </h2> </a> </div> <div class='header-desc'> The latest news and insights from Google on security and safety on the Internet </div> </div> </div></div> </div> </div>  <div class='cols-wrapper loading'> <div class='col-main-wrapper'> <div class='col-main'> <div class='section' id='main'><div class='widget Blog' data-version='1' id='Blog1'> <div class='post' data-id='1390661849546808813' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html' itemprop='url' title='Safer with Google: New intelligent, real-time protections on Android to keep you safe'> Safer with Google: New intelligent, real-time protections on Android to keep you safe </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> November 13, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Lyubov Farafonova, Product Manager and Steve Kafka, Group Product Manager, Android</span> <p> User safety is at the heart of everything we do at Google. Our mission to make technology helpful for everyone means building features that protect you while keeping your privacy top of mind. From <a href="https://blog.google/products/gmail/gmail-security-authentication-spam-protection/">Gmail’s defenses</a> that stop more than 99.9% of spam, phishing and malware, to <a href="https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html">Google Messages’ advanced security</a> that protects users from 2 billion suspicious messages a month and beyond, we're constantly developing and expanding protection features that help keep you safe. </p> <p> We're introducing two new real-time protection features that enhance your safety, all while safeguarding your privacy: Scam Detection in Phone by Google to protect you from scams and fraud, and Google Play Protect live threat detection with real-time alerts to protect you from malware and dangerous apps. </p> <p> These new security features are available first on Pixel, and are coming soon to more Android devices. </p> <p> <h3><strong>More intelligent AI-powered protection against scams</strong></h3> </p> <p> Scammers steal over <a href="https://www.newswire.com/news/global-losses-to-scammers-exceed-1-trillion-as-1-in-4-lose-money-to-22145725">$1 trillion dollars</a> a year from people, and phone calls are their favorite way to do it. Even more alarming, scam calls are evolving, becoming <a href="https://www.thecut.com/article/amazon-scam-call-ftc-arrest-warrants.html">increasingly more sophisticated</a>, damaging and harder to identify. That’s why we’re using the best of Google AI to identify and stop scams before they can do harm with Scam Detection. </p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1uV5Xu6fc-JDzLuqalOaPLR9zCpmdkR8fpXVl120zEFi5kXkXVo6XIx5mxvKb3kFQQvKE3k5xvVcVB-Bu7HwNQ8glkjc9mNHEma5QYKtZc8-Bbh-RR7lK_oR-IjhnBBZZo1pg_qK35miAiMRJc0gXNZbnXDT79NdzQ5go3RvClMmv_Nt5cLyU2-v5t4u/s1600/image1%20%285%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="504" data-original-width="840" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1uV5Xu6fc-JDzLuqalOaPLR9zCpmdkR8fpXVl120zEFi5kXkXVo6XIx5mxvKb3kFQQvKE3k5xvVcVB-Bu7HwNQ8glkjc9mNHEma5QYKtZc8-Bbh-RR7lK_oR-IjhnBBZZo1pg_qK35miAiMRJc0gXNZbnXDT79NdzQ5go3RvClMmv_Nt5cLyU2-v5t4u/s1600/image1%20%285%29.png"/></a></div> </p> <p> <strong>Real-time protection, built with your privacy in mind.</strong><br> </p> <ul> <li><strong>Real-time defense, right on your device:</strong> Scam Detection uses powerful on-device AI to notify you of a potential scam call happening in real-time by detecting conversation patterns commonly associated with scams. For example, if a caller claims to be from your bank and asks you to urgently transfer funds due to an alleged account breach, Scam Detection will process the call to determine whether the call is likely spam and, if so, can provide an audio and haptic alert and visual warning that the call may be a scam. </li> <li><strong>Private by design, you’re always in control:</strong> We’ve built Scam Detection to protect your privacy and ensure you’re always in control of your data. Scam Detection is off by default, and you can decide whether you want to activate it for future calls. At any time, you can turn it off for all calls in the Phone app Settings, or during a particular call. The AI detection model and processing are fully on-device, which means that no conversation audio or transcription is stored on the device, sent to Google servers or anywhere else, or retrievable after the call.</li> <li><strong>Cutting-edge AI protection, now on more Pixel phones:</strong> <a href="https://deepmind.google/technologies/gemini/nano/">Gemini Nano</a>, our advanced on-device AI model, powers Scam Detection on Pixel 9 series devices. As part of our commitment to bring powerful AI features to even more devices, this AI-powered protection is available to Pixel 6+ users thanks to other robust Google on-device machine learning models. <br></li> </ul> <p> We’re now rolling out Scam Detection to English-speaking Phone by Google public beta users in the U.S. with a Pixel 6 or newer device. <br> </p> <p> To provide feedback on your experience, please click on Phone by Google App -> Menu -> Help & Feedback -> Send Feedback. We look forward to learning from this beta and your feedback, and we’ll share more about Scam Detection in the months ahead. </p> <p> <h3><strong>More real-time alerts to protect you from bad apps </strong></h3> <p> Google Play Protect works non-stop to protect you in <a href="https://security.googleblog.com/2023/10/enhanced-google-play-protect-real-time.html">real-time</a> from malware and unsafe apps. Play Protect analyzes behavioral signals related to the use of sensitive permissions and interactions with other apps and services.<br><br>With live threat detection, if a harmful app is found, you'll now receive a real-time alert, allowing you to take immediate action to protect your device. By looking at actual activity patterns of apps, live threat detection can now find malicious apps that try extra hard to hide their behavior or lie dormant for a time before engaging in suspicious activity. </p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE8-vUuJySoAsx2T3pxiekXCeV3gwGP4sT4tIlVSgzOIaqQzeZRmQ5-c557Pz43l4bAbJ49CVL1lQm7ilp_xNObhMf0x5v1Qn9ivnx7DfU_wnTVX639q0-_Wv0nrX_FFJYY1KKvyKGZAJyZo3U3HfudNKBn-sYTeWpnFWuw1I89FhRPkDnLMA0aY557OX7/s1999/image2%20%281%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="1999" data-original-width="952" height="600" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE8-vUuJySoAsx2T3pxiekXCeV3gwGP4sT4tIlVSgzOIaqQzeZRmQ5-c557Pz43l4bAbJ49CVL1lQm7ilp_xNObhMf0x5v1Qn9ivnx7DfU_wnTVX639q0-_Wv0nrX_FFJYY1KKvyKGZAJyZo3U3HfudNKBn-sYTeWpnFWuw1I89FhRPkDnLMA0aY557OX7/s600/image2%20%281%29.png"/></a></div> <p> At launch, live threat detection will focus on stalkerware, code that may collect personal or sensitive data for monitoring purposes without user consent, and we will explore expanding its detection to other types of harmful apps in the future. All of this protection happens on your device in a privacy preserving way through <a href="https://security.googleblog.com/2022/12/trust-in-transparency-private-compute.html">Private Compute Core</a>, which allows us to protect users without collecting data. </p> <p> Live threat detection with real-time alerts in Google Play Protect are now available on Pixel 6+ devices and will be coming to additional phone makers in the coming months. </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Lyubov Farafonova, Product Manager and Steve Kafka, Group Product Manager, Android</span> <p> User safety is at the heart of everything we do at Google. Our mission to make technology helpful for everyone means building features that protect you while keeping your privacy top of mind. From <a href="https://blog.google/products/gmail/gmail-security-authentication-spam-protection/">Gmail’s defenses</a> that stop more than 99.9% of spam, phishing and malware, to <a href="https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html">Google Messages’ advanced security</a> that protects users from 2 billion suspicious messages a month and beyond, we're constantly developing and expanding protection features that help keep you safe. </p> <p> We're introducing two new real-time protection features that enhance your safety, all while safeguarding your privacy: Scam Detection in Phone by Google to protect you from scams and fraud, and Google Play Protect live threat detection with real-time alerts to protect you from malware and dangerous apps. </p> <p> These new security features are available first on Pixel, and are coming soon to more Android devices. </p> <p> <h3><strong>More intelligent AI-powered protection against scams</strong></h3> </p> <p> Scammers steal over <a href="https://www.newswire.com/news/global-losses-to-scammers-exceed-1-trillion-as-1-in-4-lose-money-to-22145725">$1 trillion dollars</a> a year from people, and phone calls are their favorite way to do it. Even more alarming, scam calls are evolving, becoming <a href="https://www.thecut.com/article/amazon-scam-call-ftc-arrest-warrants.html">increasingly more sophisticated</a>, damaging and harder to identify. That’s why we’re using the best of Google AI to identify and stop scams before they can do harm with Scam Detection. </p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1uV5Xu6fc-JDzLuqalOaPLR9zCpmdkR8fpXVl120zEFi5kXkXVo6XIx5mxvKb3kFQQvKE3k5xvVcVB-Bu7HwNQ8glkjc9mNHEma5QYKtZc8-Bbh-RR7lK_oR-IjhnBBZZo1pg_qK35miAiMRJc0gXNZbnXDT79NdzQ5go3RvClMmv_Nt5cLyU2-v5t4u/s1600/image1%20%285%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="504" data-original-width="840" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1uV5Xu6fc-JDzLuqalOaPLR9zCpmdkR8fpXVl120zEFi5kXkXVo6XIx5mxvKb3kFQQvKE3k5xvVcVB-Bu7HwNQ8glkjc9mNHEma5QYKtZc8-Bbh-RR7lK_oR-IjhnBBZZo1pg_qK35miAiMRJc0gXNZbnXDT79NdzQ5go3RvClMmv_Nt5cLyU2-v5t4u/s1600/image1%20%285%29.png"/></a></div> </p> <p> <strong>Real-time protection, built with your privacy in mind.</strong><br> </p> <ul> <li><strong>Real-time defense, right on your device:</strong> Scam Detection uses powerful on-device AI to notify you of a potential scam call happening in real-time by detecting conversation patterns commonly associated with scams. For example, if a caller claims to be from your bank and asks you to urgently transfer funds due to an alleged account breach, Scam Detection will process the call to determine whether the call is likely spam and, if so, can provide an audio and haptic alert and visual warning that the call may be a scam. </li> <li><strong>Private by design, you’re always in control:</strong> We’ve built Scam Detection to protect your privacy and ensure you’re always in control of your data. Scam Detection is off by default, and you can decide whether you want to activate it for future calls. At any time, you can turn it off for all calls in the Phone app Settings, or during a particular call. The AI detection model and processing are fully on-device, which means that no conversation audio or transcription is stored on the device, sent to Google servers or anywhere else, or retrievable after the call.</li> <li><strong>Cutting-edge AI protection, now on more Pixel phones:</strong> <a href="https://deepmind.google/technologies/gemini/nano/">Gemini Nano</a>, our advanced on-device AI model, powers Scam Detection on Pixel 9 series devices. As part of our commitment to bring powerful AI features to even more devices, this AI-powered protection is available to Pixel 6+ users thanks to other robust Google on-device machine learning models. <br></li> </ul> <p> We’re now rolling out Scam Detection to English-speaking Phone by Google public beta users in the U.S. with a Pixel 6 or newer device. <br> </p> <p> To provide feedback on your experience, please click on Phone by Google App -> Menu -> Help & Feedback -> Send Feedback. We look forward to learning from this beta and your feedback, and we’ll share more about Scam Detection in the months ahead. </p> <p> <h3><strong>More real-time alerts to protect you from bad apps </strong></h3> <p> Google Play Protect works non-stop to protect you in <a href="https://security.googleblog.com/2023/10/enhanced-google-play-protect-real-time.html">real-time</a> from malware and unsafe apps. Play Protect analyzes behavioral signals related to the use of sensitive permissions and interactions with other apps and services.<br><br>With live threat detection, if a harmful app is found, you'll now receive a real-time alert, allowing you to take immediate action to protect your device. By looking at actual activity patterns of apps, live threat detection can now find malicious apps that try extra hard to hide their behavior or lie dormant for a time before engaging in suspicious activity. </p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE8-vUuJySoAsx2T3pxiekXCeV3gwGP4sT4tIlVSgzOIaqQzeZRmQ5-c557Pz43l4bAbJ49CVL1lQm7ilp_xNObhMf0x5v1Qn9ivnx7DfU_wnTVX639q0-_Wv0nrX_FFJYY1KKvyKGZAJyZo3U3HfudNKBn-sYTeWpnFWuw1I89FhRPkDnLMA0aY557OX7/s1999/image2%20%281%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="1999" data-original-width="952" height="600" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE8-vUuJySoAsx2T3pxiekXCeV3gwGP4sT4tIlVSgzOIaqQzeZRmQ5-c557Pz43l4bAbJ49CVL1lQm7ilp_xNObhMf0x5v1Qn9ivnx7DfU_wnTVX639q0-_Wv0nrX_FFJYY1KKvyKGZAJyZo3U3HfudNKBn-sYTeWpnFWuw1I89FhRPkDnLMA0aY557OX7/s600/image2%20%281%29.png"/></a></div> <p> At launch, live threat detection will focus on stalkerware, code that may collect personal or sensitive data for monitoring purposes without user consent, and we will explore expanding its detection to other types of harmful apps in the future. All of this protection happens on your device in a privacy preserving way through <a href="https://security.googleblog.com/2022/12/trust-in-transparency-private-compute.html">Private Compute Core</a>, which allows us to protect users without collecting data. </p> <p> Live threat detection with real-time alerts in Google Play Protect are now available on Pixel 6+ devices and will be coming to additional phone makers in the coming months. </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:Safer with Google: New intelligent, real-time protections on Android to keep you safe&url=https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html' data-url='https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/11/new-real-time-protections-on-Android.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> , <a class='label' href='https://security.googleblog.com/search/label/pixel' rel='tag'> pixel </a> </span> </div> </div> </div> <div class='post' data-id='7349771731089105672' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html' itemprop='url' title='5 new protections on Google Messages to help keep you safe'> 5 new protections on Google Messages to help keep you safe </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> October 22, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Jan Jedrzejowicz, Director of Product, Android and Business Communications; Alberto Pastor Nieto, Sr. Product Manager Google Messages and RCS Spam and Abuse; Stephan Somogyi, Product Lead, User Protection; Branden Archer, Software Engineer</span> <p> Every day, over a billion people use <a href="http://messages.google.com">Google Messages</a> to communicate. That’s why we’ve made security a top priority, building in powerful on-device, AI-powered filters and advanced security that protects users from 2 billion suspicious messages a month. With end-to-end encrypted<sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup> RCS conversations, you can communicate privately with other Google Messages RCS users. And we’re not stopping there. We're committed to constantly developing new controls and features to make your conversations on Google Messages even more secure and private. </p> <p> <strong>As part of cybersecurity awareness month, we're sharing five new protections to help keep you safe while using Google Messages on Android:</strong> </p> <ol> <li><strong>Enhanced detection protects you from package delivery and job scams. </strong> Google Messages is adding new protections against scam texts that may seem harmless at first but can eventually lead to fraud. For <a href="https://support.google.com/messages/answer/9131090?hl=en#:~:text=Sign%20up%20for%20beta%20testing,Follow%20the%20instructions.">Google Messages beta users</a><sup id="fnref2"><a href="#fn2" rel="footnote">2</a></sup>, we’re rolling out enhanced scam detection, with improved analysis of scammy texts, starting with a focus on package delivery and job seeking messages. When Google Messages suspects a potential scam text, it will automatically move the message into your spam folder or warn you. Google Messages uses on-device machine learning models to classify these scams, so your conversations stay private and the content is never sent to Google unless you report spam. We’re rolling this enhancement out now to Google Messages beta users who have spam protection enabled.</li> <li><strong>Intelligent warnings alert you about potentially dangerous links</strong>. In the past year, we’ve been piloting more protections for Google Messages users when they receive text messages with potentially dangerous links. In India, Thailand, Malaysia and Singapore, Google Messages warns users when they get a link from unknown senders and blocks messages with links from suspicious senders. We’re in the process of expanding this feature globally later this year.</li> <li><strong>Controls to turn off messages from unknown international senders</strong>. In some cases, scam text messages come from international numbers. Soon, you will be able to automatically hide messages from international senders who are not existing contacts so you don’t have to interact with them. If enabled, messages from international non-contacts will automatically be moved to the “Spam & blocked” folder. This feature will <a href="https://www.channelnewsasia.com/singapore/google-pilot-new-android-anti-scam-features-block-sms-play-protect-4682046?cid=telegram_cna_social_28112017_cna">roll out first as a pilot in Singapore</a> later this year before we look at expanding to more countries.</li> <li><strong>Sensitive Content Warnings give you control over seeing and sending images that may contain nudity. </strong>At Google, we aim to provide users with <a href="https://safety.google/content-safety/?_gl=1*1qxnom0*_up*MQ..&gclid=Cj0KCQjwjNS3BhChARIsAOxBM6qmnJ7G3JputxEJU-vd2Z8iW6YaLITy6xrXeDhK6TpCv7wEDf64JdAaAmaOEALw_wcB&gclsrc=aw.ds">a variety of ways to protect themselves against unwanted content</a>, while keeping them in control of their data. This is why we’re introducing Sensitive Content Warnings for Google Messages.<br><br>Sensitive Content Warnings is an optional feature that blurs images that may contain nudity before viewing, and then prompts with a “speed bump” that contains help-finding resources and options, including to view the content. When the feature is enabled, and an image that may contain nudity is about to be sent or forwarded, it also provides a speed bump to remind users of the risks of sending nude imagery and preventing accidental shares.<br><br>All of this happens on-device to protect your privacy and keep end-to-end encrypted message content private to only sender and recipient. Sensitive Content Warnings doesn’t allow Google access to the contents of your images, nor does Google know that nudity may have been detected. This feature is opt-in for adults, managed via Android Settings, and is opt-out for users under 18 years of age. Sensitive Content Warnings will be rolling out to Android 9+ devices including Android Go devices<sup id="fnref3"><a href="#fn3" rel="footnote">3</a></sup> with Google Messages in the coming months.</li> <li><strong>More confirmation about who you’re messaging. </strong>To help you avoid sophisticated messaging threats where an attacker tries to impersonate one of your contacts, we’re working to add a contact verifying feature to Android. This new feature will allow you to verify your contacts' public keys so you can confirm you’re communicating with the person you intend to message. We’re creating a unified system for public key verification across different apps, which you can verify through QR code scanning or number comparison. This feature will be launching next year for Android 9+ devices, with support for messaging apps including Google Messages. <p> These are just some of the new and upcoming features that you can use to better protect yourself when sending and receiving messages. <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.messaging">Download Google Messages</a> from the Google Play Store to enjoy these protections and controls and learn more about Google Messages <a href="https://www.android.com/google-messages/">here</a>. </p> <p> </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> End-to-end encryption is currently available between Google Messages users. Availability of RCS varies by region and carrier. <a href="#fnref1" rev="footnote">↩</a><li id="fn2"> <p> Availability of features may vary by market and device. Sign up for beta testing and a data plan may be required.  <a href="#fnref2" rev="footnote">↩</a><li id="fn3"> <p> Requires 2 GB of RAM. <a href="#fnref3" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Jan Jedrzejowicz, Director of Product, Android and Business Communications; Alberto Pastor Nieto, Sr. Product Manager Google Messages and RCS Spam and Abuse; Stephan Somogyi, Product Lead, User Protection; Branden Archer, Software Engineer</span> <p> Every day, over a billion people use <a href="http://messages.google.com">Google Messages</a> to communicate. That’s why we’ve made security a top priority, building in powerful on-device, AI-powered filters and advanced security that protects users from 2 billion suspicious messages a month. With end-to-end encrypted<sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup> RCS conversations, you can communicate privately with other Google Messages RCS users. And we’re not stopping there. We're committed to constantly developing new controls and features to make your conversations on Google Messages even more secure and private. </p> <p> <strong>As part of cybersecurity awareness month, we're sharing five new protections to help keep you safe while using Google Messages on Android:</strong> </p> <ol> <li><strong>Enhanced detection protects you from package delivery and job scams. </strong> Google Messages is adding new protections against scam texts that may seem harmless at first but can eventually lead to fraud. For <a href="https://support.google.com/messages/answer/9131090?hl=en#:~:text=Sign%20up%20for%20beta%20testing,Follow%20the%20instructions.">Google Messages beta users</a><sup id="fnref2"><a href="#fn2" rel="footnote">2</a></sup>, we’re rolling out enhanced scam detection, with improved analysis of scammy texts, starting with a focus on package delivery and job seeking messages. When Google Messages suspects a potential scam text, it will automatically move the message into your spam folder or warn you. Google Messages uses on-device machine learning models to classify these scams, so your conversations stay private and the content is never sent to Google unless you report spam. We’re rolling this enhancement out now to Google Messages beta users who have spam protection enabled.</li> <li><strong>Intelligent warnings alert you about potentially dangerous links</strong>. In the past year, we’ve been piloting more protections for Google Messages users when they receive text messages with potentially dangerous links. In India, Thailand, Malaysia and Singapore, Google Messages warns users when they get a link from unknown senders and blocks messages with links from suspicious senders. We’re in the process of expanding this feature globally later this year.</li> <li><strong>Controls to turn off messages from unknown international senders</strong>. In some cases, scam text messages come from international numbers. Soon, you will be able to automatically hide messages from international senders who are not existing contacts so you don’t have to interact with them. If enabled, messages from international non-contacts will automatically be moved to the “Spam & blocked” folder. This feature will <a href="https://www.channelnewsasia.com/singapore/google-pilot-new-android-anti-scam-features-block-sms-play-protect-4682046?cid=telegram_cna_social_28112017_cna">roll out first as a pilot in Singapore</a> later this year before we look at expanding to more countries.</li> <li><strong>Sensitive Content Warnings give you control over seeing and sending images that may contain nudity. </strong>At Google, we aim to provide users with <a href="https://safety.google/content-safety/?_gl=1*1qxnom0*_up*MQ..&gclid=Cj0KCQjwjNS3BhChARIsAOxBM6qmnJ7G3JputxEJU-vd2Z8iW6YaLITy6xrXeDhK6TpCv7wEDf64JdAaAmaOEALw_wcB&gclsrc=aw.ds">a variety of ways to protect themselves against unwanted content</a>, while keeping them in control of their data. This is why we’re introducing Sensitive Content Warnings for Google Messages.<br><br>Sensitive Content Warnings is an optional feature that blurs images that may contain nudity before viewing, and then prompts with a “speed bump” that contains help-finding resources and options, including to view the content. When the feature is enabled, and an image that may contain nudity is about to be sent or forwarded, it also provides a speed bump to remind users of the risks of sending nude imagery and preventing accidental shares.<br><br>All of this happens on-device to protect your privacy and keep end-to-end encrypted message content private to only sender and recipient. Sensitive Content Warnings doesn’t allow Google access to the contents of your images, nor does Google know that nudity may have been detected. This feature is opt-in for adults, managed via Android Settings, and is opt-out for users under 18 years of age. Sensitive Content Warnings will be rolling out to Android 9+ devices including Android Go devices<sup id="fnref3"><a href="#fn3" rel="footnote">3</a></sup> with Google Messages in the coming months.</li> <li><strong>More confirmation about who you’re messaging. </strong>To help you avoid sophisticated messaging threats where an attacker tries to impersonate one of your contacts, we’re working to add a contact verifying feature to Android. This new feature will allow you to verify your contacts' public keys so you can confirm you’re communicating with the person you intend to message. We’re creating a unified system for public key verification across different apps, which you can verify through QR code scanning or number comparison. This feature will be launching next year for Android 9+ devices, with support for messaging apps including Google Messages. <p> These are just some of the new and upcoming features that you can use to better protect yourself when sending and receiving messages. <a href="https://play.google.com/store/apps/details?id=com.google.android.apps.messaging">Download Google Messages</a> from the Google Play Store to enjoy these protections and controls and learn more about Google Messages <a href="https://www.android.com/google-messages/">here</a>. </p> <p> </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> End-to-end encryption is currently available between Google Messages users. Availability of RCS varies by region and carrier. <a href="#fnref1" rev="footnote">↩</a><li id="fn2"> <p> Availability of features may vary by market and device. Sign up for beta testing and a data plan may be required.  <a href="#fnref2" rev="footnote">↩</a><li id="fn3"> <p> Requires 2 GB of RAM. <a href="#fnref3" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:5 new protections on Google Messages to help keep you safe&url=https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html' data-url='https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/10/5-new-protections-on-google-messages.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> </span> </div> </div> </div> <div class='post' data-id='6113831803096154662' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/10/android-theft-protection.html' itemprop='url' title='Bringing new theft protection features to Android users around the world'> Bringing new theft protection features to Android users around the world </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> October 15, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Jianing Sandra Guo, Product Manager and Nataliya Stanetsky, Staff Program Manager, Android</span> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiD7y8V_clxWfBWOLp8NIhN7_s1wHFePbdJmwuSOgwzGR_f4ft_na9QPwfjgaufchGjAExgO4ghNjP2ylPswMxaQpuTOP20UY62qgI6-kF8dFaTExum3P6GOU0fDBox4J_FD268UGcYpYyPSSaSafQGqW-Zqikav2F5N8drYKw1uy9ZuRQKNLf3GivFr65p/s1600/Android_Theft%20Protection_Blog%20Header_2096x1182_v3.2%20%281%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="1183" data-original-width="2097" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiD7y8V_clxWfBWOLp8NIhN7_s1wHFePbdJmwuSOgwzGR_f4ft_na9QPwfjgaufchGjAExgO4ghNjP2ylPswMxaQpuTOP20UY62qgI6-kF8dFaTExum3P6GOU0fDBox4J_FD268UGcYpYyPSSaSafQGqW-Zqikav2F5N8drYKw1uy9ZuRQKNLf3GivFr65p/s1600/Android_Theft%20Protection_Blog%20Header_2096x1182_v3.2%20%281%29.png"/></a></div> <p> Janine Roberta Ferreira was driving home from work in São Paulo when she stopped at a traffic light. A man suddenly appeared and broke the window of her unlocked car, grabbing her phone. She struggled with him for a moment before he wrestled the phone away and ran off. The incident left her deeply shaken. Not only was she saddened at the loss of precious data, like pictures of her nephew, but she also felt vulnerable knowing her banking information was on her phone that was just stolen by a thief. </p> <p> Situations like Janine’s highlighted the need for a comprehensive solution to phone theft that exceeded existing tools on any platform. Phone theft is a widespread concern in many countries – <a href="https://forumseguranca.org.br/wp-content/uploads/2022/07/07-anuario-2022-os-crimes-patrimoniais-no-brasil-entre-novas-e-velhas-dinamicas.pdf">97 phones are robbed or stolen every hour in Brazil</a>. The GSM Association <a href="https://www.gsma.com/solutions-and-impact/connectivity-for-good/public-policy/wp-content/uploads/2022/10/Safety-privacy-and-security-across-the-mobile-ecosystem.pdf">reports</a> millions of devices stolen every year, and the numbers continue to grow. </p> <p> With our phones becoming increasingly central to storing sensitive data, like payment information and personal details, losing one can be an unsettling experience. That’s why we developed and thoroughly <a href="https://blog.google/intl/pt-br/produtos/android-chrome-play/recursos-do-android-contra-roubo-de-celular-chegam-ao-brasil/">beta tested</a>, a full suite of features designed to protect you and your data at every stage – before, during, and after device theft. <br><strong><em><br>These advanced theft protection features are now available to users around the world through <a href="https://blog.google/products/android/android-15/" target="_blank">Android 15</a> and a Google Play Services update (Android 10+ devices). </em></strong> <div class="separator" style="clear: both; text-align: center;"><iframe class="BLOG_video_class" allowfullscreen="" youtube-src-id="8zYNNLxy9L0" width="600" height="498" src="https://www.youtube.com/embed/8zYNNLxy9L0"></iframe></div> </p> <h1><strong>AI-powered protection for your device the moment it is stolen </strong></h1> <p> <strong>Theft Detection Lock</strong> uses powerful AI to proactively protect you at the moment of a theft attempt. By using on-device machine learning, Theft Detection Lock is able to analyze various device signals to detect potential theft attempts. If the algorithm detects a potential theft attempt on your unlocked device, it locks your screen to keep thieves out. </p> <p> To protect your sensitive data if your phone is stolen, Theft Detection Lock uses device sensors to identify theft attempts. We’re working hard to bring this feature to as many devices as possible. This feature is rolling out gradually to ensure compatibility with various devices, starting today with Android devices that cover 90% of active users worldwide. Check your theft protection settings page periodically to see if your device is currently supported. </p> <p> In addition to Theft Detection Lock, <strong>Offline Device Lock</strong> protects you if a thief tries to take your device offline to extract data or avoid a remote wipe via Android’s <strong>Find My Device</strong>. If an unlocked device goes offline for prolonged periods, this feature locks the screen to ensure your phone can’t be used in the hands of a thief. </p> <p> If your Android device does become lost or stolen, <strong>Remote Lock </strong>can quickly help you secure it. Even if you can’t remember your Google account credentials in the moment of theft, you can use any device to visit <a href="http://Android.com/lock">Android.com/lock</a> and lock your phone with just a verified phone number. Remote Lock secures your device while you regain access through Android’s Find My Device – which lets you secure, locate or remotely wipe your device. As a security best practice, we always recommend <a href="https://support.google.com/googleone/answer/9149304?hl=en&co=GENIE.Platform%3DAndroid">backing up your device</a> on a continuous basis, so remotely wiping your device is not an issue. </p> <p> <em>These features are now available on most Android 10+ devices</em><sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup><em> via a Google Play Services update and must be enabled in settings. </em> </p> <h1><strong>Advanced security to deter theft before it happens </strong></h1> <p> Android 15 introduces new security features to deter theft before it happens by making it harder for thieves to access sensitive settings, apps, or reset your device for resale: <br> </p> <ul> <li>Changes to sensitive settings like Find My Device now require your PIN, password, or biometric authentication. </li> <li>Multiple failed login attempts, which could be a sign that a thief is trying to guess your password, will lock down your device, preventing unauthorized access. </li> <li>And enhanced factory reset protection makes it even harder for thieves to reset your device without your Google account credentials, significantly reducing its resale value and protecting your data. </li> </ul> <p> Later this year, we’ll launch <strong>Identity Check</strong>, an opt-in feature that will add an extra layer of protection by requiring biometric authentication when accessing critical Google account and device settings, like changing your PIN, disabling theft protection, or accessing Passkeys from an untrusted location. This helps prevent unauthorized access even if your device PIN is compromised. </p> <h1><strong>Real-world protection for billions of Android users</strong></h1> <p> By integrating advanced technology like AI and biometric authentication, we're making Android devices less appealing targets for thieves to give you greater peace of mind. These theft protection features are just one example of how Android is working to provide real-world protection for everyone. We’re dedicated to working with our partners around the world to continuously improve Android security and help you and your data stay safe. </p> <p> <em>You can turn on the new Android theft features by clicking <a href="https://www.android.com/settings/theftprotection">here</a> on a supported Android device. Learn more about our theft protection features by visiting our <a href="https://support.google.com/android/answer/15146908">help center</a>. </em> </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> Android Go smartphones, tablets and wearables are not supported <a href="#fnref1" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Jianing Sandra Guo, Product Manager and Nataliya Stanetsky, Staff Program Manager, Android</span> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiD7y8V_clxWfBWOLp8NIhN7_s1wHFePbdJmwuSOgwzGR_f4ft_na9QPwfjgaufchGjAExgO4ghNjP2ylPswMxaQpuTOP20UY62qgI6-kF8dFaTExum3P6GOU0fDBox4J_FD268UGcYpYyPSSaSafQGqW-Zqikav2F5N8drYKw1uy9ZuRQKNLf3GivFr65p/s1600/Android_Theft%20Protection_Blog%20Header_2096x1182_v3.2%20%281%29.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="1183" data-original-width="2097" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiD7y8V_clxWfBWOLp8NIhN7_s1wHFePbdJmwuSOgwzGR_f4ft_na9QPwfjgaufchGjAExgO4ghNjP2ylPswMxaQpuTOP20UY62qgI6-kF8dFaTExum3P6GOU0fDBox4J_FD268UGcYpYyPSSaSafQGqW-Zqikav2F5N8drYKw1uy9ZuRQKNLf3GivFr65p/s1600/Android_Theft%20Protection_Blog%20Header_2096x1182_v3.2%20%281%29.png"/></a></div> <p> Janine Roberta Ferreira was driving home from work in São Paulo when she stopped at a traffic light. A man suddenly appeared and broke the window of her unlocked car, grabbing her phone. She struggled with him for a moment before he wrestled the phone away and ran off. The incident left her deeply shaken. Not only was she saddened at the loss of precious data, like pictures of her nephew, but she also felt vulnerable knowing her banking information was on her phone that was just stolen by a thief. </p> <p> Situations like Janine’s highlighted the need for a comprehensive solution to phone theft that exceeded existing tools on any platform. Phone theft is a widespread concern in many countries – <a href="https://forumseguranca.org.br/wp-content/uploads/2022/07/07-anuario-2022-os-crimes-patrimoniais-no-brasil-entre-novas-e-velhas-dinamicas.pdf">97 phones are robbed or stolen every hour in Brazil</a>. The GSM Association <a href="https://www.gsma.com/solutions-and-impact/connectivity-for-good/public-policy/wp-content/uploads/2022/10/Safety-privacy-and-security-across-the-mobile-ecosystem.pdf">reports</a> millions of devices stolen every year, and the numbers continue to grow. </p> <p> With our phones becoming increasingly central to storing sensitive data, like payment information and personal details, losing one can be an unsettling experience. That’s why we developed and thoroughly <a href="https://blog.google/intl/pt-br/produtos/android-chrome-play/recursos-do-android-contra-roubo-de-celular-chegam-ao-brasil/">beta tested</a>, a full suite of features designed to protect you and your data at every stage – before, during, and after device theft. <br><strong><em><br>These advanced theft protection features are now available to users around the world through <a href="https://blog.google/products/android/android-15/" target="_blank">Android 15</a> and a Google Play Services update (Android 10+ devices). </em></strong> <div class="separator" style="clear: both; text-align: center;"><iframe class="BLOG_video_class" allowfullscreen="" youtube-src-id="8zYNNLxy9L0" width="600" height="498" src="https://www.youtube.com/embed/8zYNNLxy9L0"></iframe></div> </p> <h1><strong>AI-powered protection for your device the moment it is stolen </strong></h1> <p> <strong>Theft Detection Lock</strong> uses powerful AI to proactively protect you at the moment of a theft attempt. By using on-device machine learning, Theft Detection Lock is able to analyze various device signals to detect potential theft attempts. If the algorithm detects a potential theft attempt on your unlocked device, it locks your screen to keep thieves out. </p> <p> To protect your sensitive data if your phone is stolen, Theft Detection Lock uses device sensors to identify theft attempts. We’re working hard to bring this feature to as many devices as possible. This feature is rolling out gradually to ensure compatibility with various devices, starting today with Android devices that cover 90% of active users worldwide. Check your theft protection settings page periodically to see if your device is currently supported. </p> <p> In addition to Theft Detection Lock, <strong>Offline Device Lock</strong> protects you if a thief tries to take your device offline to extract data or avoid a remote wipe via Android’s <strong>Find My Device</strong>. If an unlocked device goes offline for prolonged periods, this feature locks the screen to ensure your phone can’t be used in the hands of a thief. </p> <p> If your Android device does become lost or stolen, <strong>Remote Lock </strong>can quickly help you secure it. Even if you can’t remember your Google account credentials in the moment of theft, you can use any device to visit <a href="http://Android.com/lock">Android.com/lock</a> and lock your phone with just a verified phone number. Remote Lock secures your device while you regain access through Android’s Find My Device – which lets you secure, locate or remotely wipe your device. As a security best practice, we always recommend <a href="https://support.google.com/googleone/answer/9149304?hl=en&co=GENIE.Platform%3DAndroid">backing up your device</a> on a continuous basis, so remotely wiping your device is not an issue. </p> <p> <em>These features are now available on most Android 10+ devices</em><sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup><em> via a Google Play Services update and must be enabled in settings. </em> </p> <h1><strong>Advanced security to deter theft before it happens </strong></h1> <p> Android 15 introduces new security features to deter theft before it happens by making it harder for thieves to access sensitive settings, apps, or reset your device for resale: <br> </p> <ul> <li>Changes to sensitive settings like Find My Device now require your PIN, password, or biometric authentication. </li> <li>Multiple failed login attempts, which could be a sign that a thief is trying to guess your password, will lock down your device, preventing unauthorized access. </li> <li>And enhanced factory reset protection makes it even harder for thieves to reset your device without your Google account credentials, significantly reducing its resale value and protecting your data. </li> </ul> <p> Later this year, we’ll launch <strong>Identity Check</strong>, an opt-in feature that will add an extra layer of protection by requiring biometric authentication when accessing critical Google account and device settings, like changing your PIN, disabling theft protection, or accessing Passkeys from an untrusted location. This helps prevent unauthorized access even if your device PIN is compromised. </p> <h1><strong>Real-world protection for billions of Android users</strong></h1> <p> By integrating advanced technology like AI and biometric authentication, we're making Android devices less appealing targets for thieves to give you greater peace of mind. These theft protection features are just one example of how Android is working to provide real-world protection for everyone. We’re dedicated to working with our partners around the world to continuously improve Android security and help you and your data stay safe. </p> <p> <em>You can turn on the new Android theft features by clicking <a href="https://www.android.com/settings/theftprotection">here</a> on a supported Android device. Learn more about our theft protection features by visiting our <a href="https://support.google.com/android/answer/15146908">help center</a>. </em> </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> Android Go smartphones, tablets and wearables are not supported <a href="#fnref1" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:Bringing new theft protection features to Android users around the world&url=https://security.googleblog.com/2024/10/android-theft-protection.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/10/android-theft-protection.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/10/android-theft-protection.html' data-url='https://security.googleblog.com/2024/10/android-theft-protection.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/10/android-theft-protection.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> </span> </div> </div> </div> <div class='post' data-id='3277683090762811159' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html' itemprop='url' title='Pixel's Proactive Approach to Security: Addressing Vulnerabilities in Cellular Modems'> Pixel's Proactive Approach to Security: Addressing Vulnerabilities in Cellular Modems </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> October 3, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Sherk Chung, Stephan Chen, Pixel team, and Roger Piqueras Jover, Ivan Lozano, Android team</span> <p> Pixel phones have earned a well-deserved reputation for being security-conscious. In this blog, we'll take a peek under the hood to see how Pixel mitigates common exploits on cellular basebands. </p> <p> Smartphones have become an integral part of our lives, but few of us think about the complex software that powers them, especially the cellular baseband – the processor on the device responsible for handling all cellular communication (such as LTE, 4G, and 5G). Most smartphones use cellular baseband processors with tight performance constraints, making security hardening difficult. Security researchers have increasingly exploited this attack vector and routinely demonstrated the possibility of exploiting basebands used in popular smartphones. </p> <p> The good news is that Pixel has been deploying security hardening mitigations in our basebands for years, and Pixel 9 represents the most hardened baseband we've shipped yet. Below, we’ll dive into why this is so important, how specifically we’ve improved security, and what this means for our users. </p> <p> <strong>The Cellular Baseband</strong> </p> <p> The cellular baseband within a smartphone is responsible for managing the device's connectivity to cellular networks. This function inherently involves processing external inputs, which may originate from untrusted sources. For instance, malicious actors can <a href="https://i.blackhat.com/BH-US-23/Presentations/US-23-Karimi-Over-the-Air-Under-the-Radar.pdf">employ false base stations to inject fabricated or manipulated network packets</a>. In certain protocols like IMS (IP Multimedia Subsystem), this can be executed remotely from any global location using an IMS client. </p> <p> The firmware within the cellular baseband, similar to any software, is susceptible to bugs and errors. In the context of the baseband, these software vulnerabilities pose a significant concern due to the heightened exposure of this component within the device's attack surface. There is ample evidence <a href="https://i.blackhat.com/USA21/Wednesday-Handouts/us-21-Over-The-Air-Baseband-Exploit-Gaining-Remote-Code-Execution-On-5G-Smartphones.pdf">demonstrating the exploitation of software bugs in modem basebands to achieve remote code execution</a>, highlighting the critical risk associated with such vulnerabilities. </p> <p> <strong>The State of Baseband Security</strong> </p> <p> Baseband security has emerged as a prominent area of research, with <a href="https://i.blackhat.com/USA21/Wednesday-Handouts/us-21-Over-The-Air-Baseband-Exploit-Gaining-Remote-Code-Execution-On-5G-Smartphones.pdf">demonstrations of software bug exploitation</a> featuring in numerous security conferences. Many of these conferences now also incorporate <a href="https://www.offensivecon.org/trainings/2023/baseband-exploitation.html">training</a> <a href="https://www.hexacon.fr/trainer/ribeiro_burke/">sessions</a> dedicated to baseband firmware emulation, analysis, and exploitation techniques. </p> <p> Recent reports by security researchers have noted that most basebands lack exploit mitigations commonly deployed elsewhere and considered best practices in software development. Mature <a href="https://source.android.com/docs/security/test/sanitizers">software hardening techniques that are commonplace in the Android operating system</a>, for example, are often absent from cellular firmwares of many popular smartphones. </p> <p> There are clear indications that exploit vendors and cyber-espionage firms abuse these vulnerabilities to breach the privacy of individuals without their consent. For example, 0-day exploits in the cellular baseband are being used <a href="https://securitylab.amnesty.org/latest/2023/10/technical-deep-dive-into-intellexa-alliance-surveillance-products/">to deploy the Predator malware in smartphones</a>. Additionally, exploit marketplaces <a href="https://zerodium.com/program.html">explicitly list baseband exploits</a>, often with relatively low payouts, suggesting a potential abundance of such vulnerabilities. These vulnerabilities allow attackers to gain unauthorized access to a device, execute arbitrary code, escalate privileges, or extract sensitive information. </p> <p> Recognizing these industry trends, Android and Pixel have proactively updated their <a href="https://bughunters.google.com/about/rules/android-friends/6171833274204160/android-and-google-devices-security-reward-program-rules">Vulnerability Rewards Program</a> in recent years, placing a greater emphasis on <a href="https://source.android.com/docs/security/overview/updates-resources#severity">identifying and addressing exploitable bugs in connectivity firmware</a>. </p> <p> <strong>Building a Fortress: Proactive Defenses in the Pixel Modem</strong> </p> <p> In response to the rising threat of baseband security attacks, Pixel has incrementally incorporated many of the following proactive defenses over the years, with the Pixel 9 phones (Pixel 9, Pixel 9 Pro, Pixel 9 Pro XL and Pixel 9 Pro Fold) showcasing the latest features: </p> <ul> <li><strong>Bounds Sanitizer:</strong> Buffer overflows occur when a bug in code allows attackers to cram too much data into a space, causing it to spill over and potentially corrupt other data or execute malicious code. Bounds Sanitizer automatically adds checks around a specific subset of memory accesses to ensure that code does not access memory outside of designated areas, preventing memory corruption. <li><strong>Integer Overflow Sanitizer:</strong> Numbers matter, and when they get too large an “overflow” can cause them to be incorrectly interpreted as smaller values. The reverse can happen as well, a number can overflow in the negative direction as well and be incorrectly interpreted as a larger value. These overflows can be exploited by attackers to cause unexpected behavior. Integer Overflow Sanitizer adds checks around these calculations to eliminate the risk of memory corruption from this class of vulnerabilities. <li><strong>Stack Canaries:</strong> Stack canaries are like tripwires set up to ensure code executes in the expected order. If a hacker tries to exploit a vulnerability in the stack to change the flow of execution without being mindful of the canary, the canary "trips," alerting the system to a potential attack. <li><strong>Control Flow Integrity (CFI): </strong>Similar to stack canaries, CFI makes sure code execution is constrained along a limited number of paths. If an attacker tries to deviate from the allowed set of execution paths, CFI causes the modem to restart rather than take the unallowed execution path. <li><strong>Auto-Initialize Stack Variables:</strong> When memory is designated for use, it’s not normally initialized in C/C+ as it is expected the developer will correctly set up the allocated region. When a developer fails to handle this correctly, the uninitialized values can leak sensitive data or be manipulated by attackers to gain code execution. Pixel phones automatically initialize stack variables to zero, preventing this class of vulnerabilities for stack data. </li> </ul> <p> We also leverage a number of bug detection tools, such as <a href="https://clang.llvm.org/docs/AddressSanitizer.html">address sanitizer</a>, during our testing process. This helps us <a href="https://security.googleblog.com/2023/12/hardening-cellular-basebands-in-android.html">identify software bugs and patch them prior to shipping devices to our users</a>. </p> <p> <strong>The Pixel Advantage: Combining Protections for Maximum Security</strong> </p> <p> Security hardening is difficult and our work is never done, but when these security measures are combined, they significantly increase Pixel 9’s resilience to baseband attacks. </p> <p> Pixel's proactive approach to security demonstrates a commitment to protecting its users across the entire software stack. Hardening the cellular baseband against remote attacks is just one example of how Pixel is constantly working to stay ahead of the curve when it comes to security. </p> <p> <em>Special thanks to our colleagues who supported our cellular baseband hardening efforts: Dominik Maier, Shawn Yang, Sami Tolvanen, Pirama Arumuga Nainar, Stephen Hines, Kevin Deus, Xuan Xing, Eugene Rodionov, Stephan Somogyi, Wes Johnson, Suraj Harjani, Morgan Shen, Valery Wu, Clint Chen, Cheng-Yi He, Estefany Torres, Hungyen Weng, Jerry Hung, Sherif Hanna</em> </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Sherk Chung, Stephan Chen, Pixel team, and Roger Piqueras Jover, Ivan Lozano, Android team</span> <p> Pixel phones have earned a well-deserved reputation for being security-conscious. In this blog, we'll take a peek under the hood to see how Pixel mitigates common exploits on cellular basebands. </p> <p> Smartphones have become an integral part of our lives, but few of us think about the complex software that powers them, especially the cellular baseband – the processor on the device responsible for handling all cellular communication (such as LTE, 4G, and 5G). Most smartphones use cellular baseband processors with tight performance constraints, making security hardening difficult. Security researchers have increasingly exploited this attack vector and routinely demonstrated the possibility of exploiting basebands used in popular smartphones. </p> <p> The good news is that Pixel has been deploying security hardening mitigations in our basebands for years, and Pixel 9 represents the most hardened baseband we've shipped yet. Below, we’ll dive into why this is so important, how specifically we’ve improved security, and what this means for our users. </p> <p> <strong>The Cellular Baseband</strong> </p> <p> The cellular baseband within a smartphone is responsible for managing the device's connectivity to cellular networks. This function inherently involves processing external inputs, which may originate from untrusted sources. For instance, malicious actors can <a href="https://i.blackhat.com/BH-US-23/Presentations/US-23-Karimi-Over-the-Air-Under-the-Radar.pdf">employ false base stations to inject fabricated or manipulated network packets</a>. In certain protocols like IMS (IP Multimedia Subsystem), this can be executed remotely from any global location using an IMS client. </p> <p> The firmware within the cellular baseband, similar to any software, is susceptible to bugs and errors. In the context of the baseband, these software vulnerabilities pose a significant concern due to the heightened exposure of this component within the device's attack surface. There is ample evidence <a href="https://i.blackhat.com/USA21/Wednesday-Handouts/us-21-Over-The-Air-Baseband-Exploit-Gaining-Remote-Code-Execution-On-5G-Smartphones.pdf">demonstrating the exploitation of software bugs in modem basebands to achieve remote code execution</a>, highlighting the critical risk associated with such vulnerabilities. </p> <p> <strong>The State of Baseband Security</strong> </p> <p> Baseband security has emerged as a prominent area of research, with <a href="https://i.blackhat.com/USA21/Wednesday-Handouts/us-21-Over-The-Air-Baseband-Exploit-Gaining-Remote-Code-Execution-On-5G-Smartphones.pdf">demonstrations of software bug exploitation</a> featuring in numerous security conferences. Many of these conferences now also incorporate <a href="https://www.offensivecon.org/trainings/2023/baseband-exploitation.html">training</a> <a href="https://www.hexacon.fr/trainer/ribeiro_burke/">sessions</a> dedicated to baseband firmware emulation, analysis, and exploitation techniques. </p> <p> Recent reports by security researchers have noted that most basebands lack exploit mitigations commonly deployed elsewhere and considered best practices in software development. Mature <a href="https://source.android.com/docs/security/test/sanitizers">software hardening techniques that are commonplace in the Android operating system</a>, for example, are often absent from cellular firmwares of many popular smartphones. </p> <p> There are clear indications that exploit vendors and cyber-espionage firms abuse these vulnerabilities to breach the privacy of individuals without their consent. For example, 0-day exploits in the cellular baseband are being used <a href="https://securitylab.amnesty.org/latest/2023/10/technical-deep-dive-into-intellexa-alliance-surveillance-products/">to deploy the Predator malware in smartphones</a>. Additionally, exploit marketplaces <a href="https://zerodium.com/program.html">explicitly list baseband exploits</a>, often with relatively low payouts, suggesting a potential abundance of such vulnerabilities. These vulnerabilities allow attackers to gain unauthorized access to a device, execute arbitrary code, escalate privileges, or extract sensitive information. </p> <p> Recognizing these industry trends, Android and Pixel have proactively updated their <a href="https://bughunters.google.com/about/rules/android-friends/6171833274204160/android-and-google-devices-security-reward-program-rules">Vulnerability Rewards Program</a> in recent years, placing a greater emphasis on <a href="https://source.android.com/docs/security/overview/updates-resources#severity">identifying and addressing exploitable bugs in connectivity firmware</a>. </p> <p> <strong>Building a Fortress: Proactive Defenses in the Pixel Modem</strong> </p> <p> In response to the rising threat of baseband security attacks, Pixel has incrementally incorporated many of the following proactive defenses over the years, with the Pixel 9 phones (Pixel 9, Pixel 9 Pro, Pixel 9 Pro XL and Pixel 9 Pro Fold) showcasing the latest features: </p> <ul> <li><strong>Bounds Sanitizer:</strong> Buffer overflows occur when a bug in code allows attackers to cram too much data into a space, causing it to spill over and potentially corrupt other data or execute malicious code. Bounds Sanitizer automatically adds checks around a specific subset of memory accesses to ensure that code does not access memory outside of designated areas, preventing memory corruption. <li><strong>Integer Overflow Sanitizer:</strong> Numbers matter, and when they get too large an “overflow” can cause them to be incorrectly interpreted as smaller values. The reverse can happen as well, a number can overflow in the negative direction as well and be incorrectly interpreted as a larger value. These overflows can be exploited by attackers to cause unexpected behavior. Integer Overflow Sanitizer adds checks around these calculations to eliminate the risk of memory corruption from this class of vulnerabilities. <li><strong>Stack Canaries:</strong> Stack canaries are like tripwires set up to ensure code executes in the expected order. If a hacker tries to exploit a vulnerability in the stack to change the flow of execution without being mindful of the canary, the canary "trips," alerting the system to a potential attack. <li><strong>Control Flow Integrity (CFI): </strong>Similar to stack canaries, CFI makes sure code execution is constrained along a limited number of paths. If an attacker tries to deviate from the allowed set of execution paths, CFI causes the modem to restart rather than take the unallowed execution path. <li><strong>Auto-Initialize Stack Variables:</strong> When memory is designated for use, it’s not normally initialized in C/C+ as it is expected the developer will correctly set up the allocated region. When a developer fails to handle this correctly, the uninitialized values can leak sensitive data or be manipulated by attackers to gain code execution. Pixel phones automatically initialize stack variables to zero, preventing this class of vulnerabilities for stack data. </li> </ul> <p> We also leverage a number of bug detection tools, such as <a href="https://clang.llvm.org/docs/AddressSanitizer.html">address sanitizer</a>, during our testing process. This helps us <a href="https://security.googleblog.com/2023/12/hardening-cellular-basebands-in-android.html">identify software bugs and patch them prior to shipping devices to our users</a>. </p> <p> <strong>The Pixel Advantage: Combining Protections for Maximum Security</strong> </p> <p> Security hardening is difficult and our work is never done, but when these security measures are combined, they significantly increase Pixel 9’s resilience to baseband attacks. </p> <p> Pixel's proactive approach to security demonstrates a commitment to protecting its users across the entire software stack. Hardening the cellular baseband against remote attacks is just one example of how Pixel is constantly working to stay ahead of the curve when it comes to security. </p> <p> <em>Special thanks to our colleagues who supported our cellular baseband hardening efforts: Dominik Maier, Shawn Yang, Sami Tolvanen, Pirama Arumuga Nainar, Stephen Hines, Kevin Deus, Xuan Xing, Eugene Rodionov, Stephan Somogyi, Wes Johnson, Suraj Harjani, Morgan Shen, Valery Wu, Clint Chen, Cheng-Yi He, Estefany Torres, Hungyen Weng, Jerry Hung, Sherif Hanna</em> </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:Pixel's Proactive Approach to Security: Addressing Vulnerabilities in Cellular Modems&url=https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html' data-url='https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/10/pixel-proactive-security-cellular-modems.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> , <a class='label' href='https://security.googleblog.com/search/label/pixel' rel='tag'> pixel </a> </span> </div> </div> </div> <div class='post' data-id='5290724433058734199' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html' itemprop='url' title='Eliminating Memory Safety Vulnerabilities at the Source'> Eliminating Memory Safety Vulnerabilities at the Source </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> September 25, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Jeff Vander Stoep - Android team, and Alex Rebert - Security Foundations<br /><br /></span> <p> Memory safety vulnerabilities remain a pervasive threat to software security. At Google, we believe the path to eliminating this class of vulnerabilities at scale and building high-assurance software lies in <a href="https://blog.google/technology/safety-security/tackling-cybersecurity-vulnerabilities-through-secure-by-design/">Safe Coding</a>, a secure-by-design approach that prioritizes transitioning to memory-safe languages. </p> <p> This post demonstrates why focusing on Safe Coding for new code quickly and counterintuitively reduces the overall security risk of a codebase, finally breaking through the stubbornly high plateau of memory safety vulnerabilities and starting an exponential decline, all while being scalable and cost-effective. </p> <p> We’ll also share updated data on how the percentage of memory safety vulnerabilities in Android dropped from 76% to 24% over 6 years as development shifted to memory safe languages. </p> <h1>Counterintuitive results</h1> <p> Consider a growing codebase primarily written in memory-unsafe languages, experiencing a constant influx of memory safety vulnerabilities. What happens if we gradually transition to memory-safe languages for new features, while leaving existing code mostly untouched except for bug fixes? </p> <p> We can simulate the results. After some years, the code base has the following makeup<sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup> as new memory unsafe development slows down, and new memory safe development starts to take over: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW_r-wkHYN6aB63fR5lu4p-qEIF-pNFRKcs_nAywuoJzETX4rvHd-MeazQZPlncOi8u485JHpYM59O-3nPOaPDaMjH5LLCqxHHb4edQV44EUgB7zjNI7EXKNA-zeFJHSc2IfYXq0KfE4ANyQhyphenhyphenzDHUq-ZMX4canzYr-1g1rBAhj2shn4zYoBSGJ1X9Fgkt/s1600/image9.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW_r-wkHYN6aB63fR5lu4p-qEIF-pNFRKcs_nAywuoJzETX4rvHd-MeazQZPlncOi8u485JHpYM59O-3nPOaPDaMjH5LLCqxHHb4edQV44EUgB7zjNI7EXKNA-zeFJHSc2IfYXq0KfE4ANyQhyphenhyphenzDHUq-ZMX4canzYr-1g1rBAhj2shn4zYoBSGJ1X9Fgkt/s1600/image9.png"/></a></div> </p> <p> In the final year of our simulation, despite the growth in memory-unsafe code, the number of memory safety vulnerabilities drops significantly, a seemingly counterintuitive result not seen with other strategies: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhriISdaRMIrklNyxjeUgzdXXpuLm65UZ3BPXdpViHyy_NaHQ7rwlelqkT1Z70GRAf9144yuh4ADtes82mNOONZcbEFYivTIUrXvvWCZNvT2rDyK4ZkOU00qk_oaCTpSfVZTty4z4UqM6-Xr1tYjZbTJIvNTX0DBsRotJ0iTEztvZEoR7SSuQE1dde2p1jf/s1600/image3.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhriISdaRMIrklNyxjeUgzdXXpuLm65UZ3BPXdpViHyy_NaHQ7rwlelqkT1Z70GRAf9144yuh4ADtes82mNOONZcbEFYivTIUrXvvWCZNvT2rDyK4ZkOU00qk_oaCTpSfVZTty4z4UqM6-Xr1tYjZbTJIvNTX0DBsRotJ0iTEztvZEoR7SSuQE1dde2p1jf/s1600/image3.png"/></a></div> </p> <p> This reduction might seem paradoxical: how is this possible when the quantity of new memory unsafe code actually grew? </p> <h1>The math </h1> <p> The answer lies in an important observation: <strong>vulnerabilities decay exponentially</strong>. They have a half-life. The distribution of vulnerability lifetime follows an exponential distribution given an average vulnerability lifetime λ: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUTrTPtyvulXnZlxMEWF6rkSxoHRrNHjqhJ09jSUD_yf_3z-THg4n8oCY6b7YtEUIstSWNSOq8g4fPKLqu35A0n7lewRc1slBx07vI6KC341ItdBGJjmN0Zeq-L4Gc9f_mj2Gt9jtppMce2oI0U09dsFCIP49NECCe6XZMJdMu_kAU1G4Bsc2Xe-8VBCSg/s1600/Screenshot%202024-09-24%2011.00.53%20PM.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="47" data-original-width="227" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUTrTPtyvulXnZlxMEWF6rkSxoHRrNHjqhJ09jSUD_yf_3z-THg4n8oCY6b7YtEUIstSWNSOq8g4fPKLqu35A0n7lewRc1slBx07vI6KC341ItdBGJjmN0Zeq-L4Gc9f_mj2Gt9jtppMce2oI0U09dsFCIP49NECCe6XZMJdMu_kAU1G4Bsc2Xe-8VBCSg/s1600/Screenshot%202024-09-24%2011.00.53%20PM.png"/></a></div> </p> <p> A large-scale study of vulnerability lifetimes<sup id="fnref2"><a href="#fn2" rel="footnote">2</a></sup> published in 2022 in Usenix Security confirmed this phenomenon. Researchers found that the vast majority of vulnerabilities reside in new or recently modified code: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiY1Fp0sUM3d7vOI11Kdae3wdsekNW_GqUdUL6LnhpjSS2cyKxvp_Dr4_N8AGVAf5VDmOAUbcMpXLLH2aYcfeszpY3hr1ttvRclMb3IWMvh9npCkY9Pc5v3jvcnJom80scnkfVBbikWLN-AcfFXSO03gEPiGDE6XSEftV6DBbUYD5HX1BQLnO0bB5-iGb0/s1600/image7.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="684" data-original-width="1999" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiY1Fp0sUM3d7vOI11Kdae3wdsekNW_GqUdUL6LnhpjSS2cyKxvp_Dr4_N8AGVAf5VDmOAUbcMpXLLH2aYcfeszpY3hr1ttvRclMb3IWMvh9npCkY9Pc5v3jvcnJom80scnkfVBbikWLN-AcfFXSO03gEPiGDE6XSEftV6DBbUYD5HX1BQLnO0bB5-iGb0/s1600/image7.png"/></a></div> </p> <p> This confirms and generalizes our <a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html">observation, published in 2021</a>, that the density of Android’s memory safety bugs decreased with the age of the code, primarily residing in recent changes. </p> <p> This leads to two important takeaways: </p> <ul> <li><strong>The problem is overwhelmingly with new code</strong>, necessitating a fundamental change in how we develop code. <li><strong>Code matures and gets safer with time, exponentially</strong>, making the returns on investments like rewrites diminish over time as code gets older. </li> </ul> <p> For example, based on the average vulnerability lifetimes, 5-year-old code has a 3.4x (using lifetimes from the study) to 7.4x (using lifetimes observed in Android and Chromium) lower vulnerability density than new code. </p> <p> In real life, as with our simulation, when we start to prioritize prevention, the situation starts to rapidly improve. </p> <h1>In practice on Android</h1> <p> The Android team began prioritizing transitioning new development to memory safe languages around 2019. This decision was driven by the increasing cost and complexity of managing memory safety vulnerabilities. There’s much left to do, but the results have already been positive. Here’s the big picture in 2024, looking at total code: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1OlXyuvF9q6o3VG9Rh4OSgrEvvlJZ0D_O5uW5lp-NhF8hSxDkY98ftEfwYvFQrAGp-ftnehqJ2RU17KDyfhgI3KjeFsmJyqGmL7n_Ip1SXAnza-NSqgrsJ47HOTluyzKAb_LCpwGHtVybKg9LNgRorEKWS2LIpqrnmcPIxLRPfW9ECK_XqSQ5fjrU2WhH/s1600/image5.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1OlXyuvF9q6o3VG9Rh4OSgrEvvlJZ0D_O5uW5lp-NhF8hSxDkY98ftEfwYvFQrAGp-ftnehqJ2RU17KDyfhgI3KjeFsmJyqGmL7n_Ip1SXAnza-NSqgrsJ47HOTluyzKAb_LCpwGHtVybKg9LNgRorEKWS2LIpqrnmcPIxLRPfW9ECK_XqSQ5fjrU2WhH/s1600/image5.png"/></a></div> <p> <br> </p> <p> Despite the majority of code still being unsafe (but, crucially, getting progressively older), we’re seeing a large and continued decline in memory safety vulnerabilities. The results align with what we simulated above, and are even better, potentially as a result of our parallel efforts to improve the safety of our memory unsafe code. We first <a href="https://security.googleblog.com/2022/12/memory-safe-languages-in-android-13.html">reported</a> this decline in 2022, and we continue to see the total number of memory safety vulnerabilities dropping<sup id="fnref3"><a href="#fn3" rel="footnote">3</a></sup>. Note that the data for 2024 is extrapolated to the full year (represented as 36, but currently at 27 after the <a href="https://source.android.com/docs/security/bulletin/2024-09-01">September security bulletin</a>). <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilTxSxGJLA-FakEzfrwOMTFJ8S03bJDn6Y61pKhtEAYV0oGXi1T_kVL48uU0ojZD9IwSXIQKL-duOtU1m4uEMsxNpvC3U9N_aynQ1XkrIkyFNve9Zj3FlbxJgcdrZaCSeKKJhYpEQM_NiMQDZduorxc8hgNJccpTX_VX3XYYV3uaQCwny7duVVDMNAHWHp/s1600/image8.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilTxSxGJLA-FakEzfrwOMTFJ8S03bJDn6Y61pKhtEAYV0oGXi1T_kVL48uU0ojZD9IwSXIQKL-duOtU1m4uEMsxNpvC3U9N_aynQ1XkrIkyFNve9Zj3FlbxJgcdrZaCSeKKJhYpEQM_NiMQDZduorxc8hgNJccpTX_VX3XYYV3uaQCwny7duVVDMNAHWHp/s1600/image8.png"/></a></div> </p> <p> The percent of vulnerabilities caused by memory safety issues continues to correlate closely with the development language that’s used for new code. Memory safety issues, which accounted for 76% of Android vulnerabilities in 2019, and are currently 24% in 2024, well below the 70% industry norm, and continuing to drop. <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoFvbQ1AN4OQOiRSBNqRKGhHAsaJNSJNOQ9ixLn0ClESW2S_zQttsaTuPY06gvxrY2d9QUUCoWNFzypHX6RB4mhOyhM8fbjJjDL6uascUpVYl7hgisMWcc0lcKRrWCPKc7XXoIxzj_Hr-7nOF6N3glP05w0wsvfdGmAENLha8yZYL7mPOmPqg1Q187oiQi/s1600/image6.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoFvbQ1AN4OQOiRSBNqRKGhHAsaJNSJNOQ9ixLn0ClESW2S_zQttsaTuPY06gvxrY2d9QUUCoWNFzypHX6RB4mhOyhM8fbjJjDL6uascUpVYl7hgisMWcc0lcKRrWCPKc7XXoIxzj_Hr-7nOF6N3glP05w0wsvfdGmAENLha8yZYL7mPOmPqg1Q187oiQi/s1600/image6.png"/></a></div> </p> <p> As we noted in a <a href="https://security.googleblog.com/2022/12/memory-safe-languages-in-android-13.html">previous post, </a>memory safety vulnerabilities tend to be significantly more severe, more likely to be remotely reachable, more versatile, and more likely to be maliciously exploited than other vulnerability types. As the number of memory safety vulnerabilities have dropped, the overall security risk has dropped along with it. </p> <h1>Evolution of memory safety strategies</h1> <p> Over the past decades, the industry has pioneered significant advancements to combat memory safety vulnerabilities, with each generation of advancements contributing valuable tools and techniques that have tangibly improved software security. However, with the benefit of hindsight, it’s evident that we have yet to achieve a truly scalable and sustainable solution that achieves an acceptable level of risk: </p> <p> <strong>1st generation: reactive patching.</strong> The initial focus was mainly on fixing vulnerabilities reactively. For problems as rampant as memory safety, this incurs ongoing costs on the business and its users. Software manufacturers have to invest significant resources in responding to frequent incidents. This leads to constant security updates, leaving users vulnerable to unknown issues, and frequently albeit temporarily vulnerable to known issues, which are getting exploited <a href="https://cloud.google.com/blog/topics/threat-intelligence/time-to-exploit-trends-2021-2022/">ever faster</a>. </p> <p> <strong>2nd generation: proactive mitigating. </strong>The next approach consisted of reducing risk in vulnerable software, including a series of exploit mitigation strategies that raised the costs of crafting exploits. However, these mitigations, such as stack canaries and control-flow integrity, typically impose a recurring cost on products and development teams, often putting security and other product requirements in conflict: </p> <ul> <li>They come with performance overhead, impacting execution speed, battery life, tail latencies, and memory usage, sometimes preventing their deployment. <li>Attackers are seemingly infinitely creative, resulting in a cat-and-mouse game with defenders. In addition, the bar to develop and weaponize an exploit is regularly being lowered through <a href="https://docs.pwntools.com/en/stable/">better tooling</a> and other <a href="https://googleprojectzero.blogspot.com/2024/06/project-naptime.html">advancements</a>. </li> </ul> <p> <strong>3rd generation: proactive vulnerability discovery.</strong> The following generation focused on detecting vulnerabilities. This includes <a href="https://github.com/google/sanitizers">sanitizers</a>, often paired with fuzzing like <a href="https://llvm.org/docs/LibFuzzer.html">libfuzzer</a>, many of which were built by Google. While helpful, these methods address the symptoms of memory unsafety, not the root cause. They typically require constant pressure to get teams to fuzz, triage, and fix their findings, resulting in low coverage. Even when applied thoroughly, fuzzing does not provide high assurance, as evidenced by vulnerabilities found in extensively fuzzed code. </p> <p> Products across the industry have been significantly strengthened by these approaches, and we remain committed to responding to, mitigating, and proactively hunting for vulnerabilities. Having said that, it has become increasingly clear that those approaches are not only insufficient for reaching an acceptable level of risk in the memory-safety domain, but incur ongoing and increasing costs to developers, users, businesses, and products. As highlighted by numerous government agencies, including CISA, in their <a href="https://www.cisa.gov/sites/default/files/2023-10/SecureByDesign_1025_508c.pdf">secure-by-design report</a>, "only by incorporating secure by design practices will we break the vicious cycle of constantly creating and applying fixes." </p> <h1>The fourth generation: high-assurance prevention</h1> <p> The shift towards memory safe languages represents more than just a change in technology, it is a fundamental shift in how to approach security. This shift is not an unprecedented one, but rather a significant expansion of a proven approach. An approach that has already demonstrated remarkable <a href="https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/42934.pdf">success</a> in eliminating other vulnerability classes like XSS. </p> <p> The foundation of this shift is <a href="https://dl.acm.org/doi/10.1145/3651621">Safe Coding</a>, which enforces security invariants directly into the development platform through language features, static analysis, and API design. The result is a secure by design ecosystem providing continuous assurance at scale, safe from the risk of accidentally introducing vulnerabilities. </p> <p> The shift from previous generations to Safe Coding can be seen in the quantifiability of the assertions that are made when developing code. Instead of focusing on the interventions applied (mitigations, fuzzing), or attempting to use past performance to predict future security, Safe Coding allows us to make strong assertions about the code's properties and what can or cannot happen based on those properties. </p> <p> Safe Coding's scalability lies in its ability to reduce costs by: </p> <ul> <li><strong>Breaking the arms race:</strong> Instead of an endless arms race of defenders attempting to raise attackers’ costs by also raising their own, Safe Coding leverages our control of developer ecosystems to break this cycle by focusing on proactively building secure software from the start. <li><strong>Commoditizing high assurance memory safety:</strong> Rather than precisely tailoring interventions to each asset's assessed risk, all while managing the cost and overhead of reassessing evolving risks and applying disparate interventions, Safe Coding establishes a <a href="https://www.philvenables.com/post/raise-the-baseline-by-reducing-the-cost-of-control">high baseline of commoditized security</a>, like memory-safe languages, that affordably reduces vulnerability density across the board. Modern memory-safe languages (especially Rust) extend these principles beyond memory safety to other bug classes. <li><strong>Increasing productivity</strong>: Safe Coding improves code correctness and developer productivity by shifting bug finding further left, before the code is even checked in. We see this shift showing up in important metrics such as rollback rates (emergency code revert due to an unanticipated bug). The Android team has observed that the rollback rate of Rust changes is less than half that of C++. </li> </ul> <h1>From lessons to action</h1> <h2>Interoperability is the new rewrite</h2> <p> Based on what we’ve learned, it's become clear that we do not need to throw away or rewrite all our existing memory-unsafe code. Instead, Android is focusing on making interoperability safe and convenient as a primary capability in our memory safety journey. Interoperability offers a practical and incremental approach to adopting memory safe languages, allowing organizations to leverage existing investments in code and systems, while accelerating the development of new features. </p> <p> We recommend focusing investments on improving interoperability, as we are doing with Rust ↔︎ C++ and Rust ↔︎ <a href="https://github.com/rust-diplomat/diplomat/pull/629">Kotlin</a>. To that end, earlier this year, Google provided a <a href="https://security.googleblog.com/2024/02/improving-interoperability-between-rust-and-c.html">$1,000,000 grant</a> to the Rust Foundation, in addition to developing interoperability tooling like <a href="https://github.com/google/crubit">Crubit</a> and <a href="https://github.com/google/autocxx">autocxx</a>. </p> <h2>Role of previous generations</h2> <p> As Safe Coding continues to drive down risk, what will be the role of mitigations and proactive detection? We don’t have definitive answers in Android, but expect something like the following: </p> <ul> <li><strong>More selective use of proactive mitigations</strong>: We expect less reliance on exploit mitigations as we transition to memory-safe code, leading to not only safer software, but also more efficient software. For instance, after removing the now unnecessary sandbox, <a href="https://groups.google.com/a/chromium.org/g/chromium-dev/c/UhwVDk4HZFA">Chromium's Rust QR code generator</a> is 20 times faster. <li><strong>Decreased use, but increased effectiveness of proactive detection</strong>: We anticipate a decreased reliance on proactive detection approaches like fuzzing, but increased effectiveness, as achieving comprehensive coverage over small well-encapsulated code snippets becomes more feasible. </li> </ul> <h1>Final thoughts</h1> <p> Fighting against the math of vulnerability lifetimes has been a losing battle. Adopting Safe Coding in new code offers a paradigm shift, allowing us to leverage the inherent decay of vulnerabilities to our advantage, <em>even in large existing systems</em>. The concept is simple: once we turn off the tap of new vulnerabilities, they decrease exponentially, making all of our code safer, increasing the <a href="https://docs.google.com/presentation/d/16LZ6T-tcjgp3T8_N3m0pa5kNA1DwIsuMcQYDhpMU7uU/edit#slide=id.g3e7cac054a_0_89">effectiveness of security design</a>, and alleviating the scalability challenges associated with existing memory safety strategies such that they can be applied more effectively in a targeted manner. </p> <p> This approach has proven successful in eliminating entire vulnerability classes and its effectiveness in tackling memory safety is increasingly evident based on more than half a decade of consistent results in Android. </p> <p> We'll be sharing more about our secure-by-design efforts in the coming months. </p> <h1>Acknowledgements</h1> <p> Thanks Alice Ryhl for coding up the simulation. Thanks to Emilia Kasper, Adrian Taylor, Manish Goregaokar, Christoph Kern, and Lars Bergstrom for your helpful feedback on this post. </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> Simulation was based on numbers similar to Android and other Google projects. The code base doubles every 6 years. The average lifetime for vulnerabilities is 2.5 years. It takes 10 years to transition to memory safe languages for new code, and we use a sigmoid function to represent the transition. Note that the use of the sigmoid function is why the second chart doesn’t initially appear to be exponential. <a href="#fnref1" rev="footnote">↩</a><li id="fn2"> <p> Alexopoulos et al. <a href="https://www.usenix.org/conference/usenixsecurity22/presentation/alexopoulos">"How Long Do Vulnerabilities Live in the Code? A Large-Scale Empirical Measurement Study on FOSS Vulnerability Lifetimes"</a>. USENIX Security 22. <a href="#fnref2" rev="footnote">↩</a><li id="fn3"> <p> Unlike our simulation, these are vulnerabilities from a real code base, which comes with higher variance, as you can see in the slight increase in 2023. Vulnerability reports were unusually high that year, but in line with expectations given code growth, so while the percentage of memory safety vulnerabilities continued to drop, the absolute number increased slightly. <a href="#fnref3" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Jeff Vander Stoep - Android team, and Alex Rebert - Security Foundations<br /><br /></span> <p> Memory safety vulnerabilities remain a pervasive threat to software security. At Google, we believe the path to eliminating this class of vulnerabilities at scale and building high-assurance software lies in <a href="https://blog.google/technology/safety-security/tackling-cybersecurity-vulnerabilities-through-secure-by-design/">Safe Coding</a>, a secure-by-design approach that prioritizes transitioning to memory-safe languages. </p> <p> This post demonstrates why focusing on Safe Coding for new code quickly and counterintuitively reduces the overall security risk of a codebase, finally breaking through the stubbornly high plateau of memory safety vulnerabilities and starting an exponential decline, all while being scalable and cost-effective. </p> <p> We’ll also share updated data on how the percentage of memory safety vulnerabilities in Android dropped from 76% to 24% over 6 years as development shifted to memory safe languages. </p> <h1>Counterintuitive results</h1> <p> Consider a growing codebase primarily written in memory-unsafe languages, experiencing a constant influx of memory safety vulnerabilities. What happens if we gradually transition to memory-safe languages for new features, while leaving existing code mostly untouched except for bug fixes? </p> <p> We can simulate the results. After some years, the code base has the following makeup<sup id="fnref1"><a href="#fn1" rel="footnote">1</a></sup> as new memory unsafe development slows down, and new memory safe development starts to take over: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW_r-wkHYN6aB63fR5lu4p-qEIF-pNFRKcs_nAywuoJzETX4rvHd-MeazQZPlncOi8u485JHpYM59O-3nPOaPDaMjH5LLCqxHHb4edQV44EUgB7zjNI7EXKNA-zeFJHSc2IfYXq0KfE4ANyQhyphenhyphenzDHUq-ZMX4canzYr-1g1rBAhj2shn4zYoBSGJ1X9Fgkt/s1600/image9.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW_r-wkHYN6aB63fR5lu4p-qEIF-pNFRKcs_nAywuoJzETX4rvHd-MeazQZPlncOi8u485JHpYM59O-3nPOaPDaMjH5LLCqxHHb4edQV44EUgB7zjNI7EXKNA-zeFJHSc2IfYXq0KfE4ANyQhyphenhyphenzDHUq-ZMX4canzYr-1g1rBAhj2shn4zYoBSGJ1X9Fgkt/s1600/image9.png"/></a></div> </p> <p> In the final year of our simulation, despite the growth in memory-unsafe code, the number of memory safety vulnerabilities drops significantly, a seemingly counterintuitive result not seen with other strategies: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhriISdaRMIrklNyxjeUgzdXXpuLm65UZ3BPXdpViHyy_NaHQ7rwlelqkT1Z70GRAf9144yuh4ADtes82mNOONZcbEFYivTIUrXvvWCZNvT2rDyK4ZkOU00qk_oaCTpSfVZTty4z4UqM6-Xr1tYjZbTJIvNTX0DBsRotJ0iTEztvZEoR7SSuQE1dde2p1jf/s1600/image3.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhriISdaRMIrklNyxjeUgzdXXpuLm65UZ3BPXdpViHyy_NaHQ7rwlelqkT1Z70GRAf9144yuh4ADtes82mNOONZcbEFYivTIUrXvvWCZNvT2rDyK4ZkOU00qk_oaCTpSfVZTty4z4UqM6-Xr1tYjZbTJIvNTX0DBsRotJ0iTEztvZEoR7SSuQE1dde2p1jf/s1600/image3.png"/></a></div> </p> <p> This reduction might seem paradoxical: how is this possible when the quantity of new memory unsafe code actually grew? </p> <h1>The math </h1> <p> The answer lies in an important observation: <strong>vulnerabilities decay exponentially</strong>. They have a half-life. The distribution of vulnerability lifetime follows an exponential distribution given an average vulnerability lifetime λ: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUTrTPtyvulXnZlxMEWF6rkSxoHRrNHjqhJ09jSUD_yf_3z-THg4n8oCY6b7YtEUIstSWNSOq8g4fPKLqu35A0n7lewRc1slBx07vI6KC341ItdBGJjmN0Zeq-L4Gc9f_mj2Gt9jtppMce2oI0U09dsFCIP49NECCe6XZMJdMu_kAU1G4Bsc2Xe-8VBCSg/s1600/Screenshot%202024-09-24%2011.00.53%20PM.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="47" data-original-width="227" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUTrTPtyvulXnZlxMEWF6rkSxoHRrNHjqhJ09jSUD_yf_3z-THg4n8oCY6b7YtEUIstSWNSOq8g4fPKLqu35A0n7lewRc1slBx07vI6KC341ItdBGJjmN0Zeq-L4Gc9f_mj2Gt9jtppMce2oI0U09dsFCIP49NECCe6XZMJdMu_kAU1G4Bsc2Xe-8VBCSg/s1600/Screenshot%202024-09-24%2011.00.53%20PM.png"/></a></div> </p> <p> A large-scale study of vulnerability lifetimes<sup id="fnref2"><a href="#fn2" rel="footnote">2</a></sup> published in 2022 in Usenix Security confirmed this phenomenon. Researchers found that the vast majority of vulnerabilities reside in new or recently modified code: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiY1Fp0sUM3d7vOI11Kdae3wdsekNW_GqUdUL6LnhpjSS2cyKxvp_Dr4_N8AGVAf5VDmOAUbcMpXLLH2aYcfeszpY3hr1ttvRclMb3IWMvh9npCkY9Pc5v3jvcnJom80scnkfVBbikWLN-AcfFXSO03gEPiGDE6XSEftV6DBbUYD5HX1BQLnO0bB5-iGb0/s1600/image7.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="684" data-original-width="1999" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgiY1Fp0sUM3d7vOI11Kdae3wdsekNW_GqUdUL6LnhpjSS2cyKxvp_Dr4_N8AGVAf5VDmOAUbcMpXLLH2aYcfeszpY3hr1ttvRclMb3IWMvh9npCkY9Pc5v3jvcnJom80scnkfVBbikWLN-AcfFXSO03gEPiGDE6XSEftV6DBbUYD5HX1BQLnO0bB5-iGb0/s1600/image7.png"/></a></div> </p> <p> This confirms and generalizes our <a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html">observation, published in 2021</a>, that the density of Android’s memory safety bugs decreased with the age of the code, primarily residing in recent changes. </p> <p> This leads to two important takeaways: </p> <ul> <li><strong>The problem is overwhelmingly with new code</strong>, necessitating a fundamental change in how we develop code. <li><strong>Code matures and gets safer with time, exponentially</strong>, making the returns on investments like rewrites diminish over time as code gets older. </li> </ul> <p> For example, based on the average vulnerability lifetimes, 5-year-old code has a 3.4x (using lifetimes from the study) to 7.4x (using lifetimes observed in Android and Chromium) lower vulnerability density than new code. </p> <p> In real life, as with our simulation, when we start to prioritize prevention, the situation starts to rapidly improve. </p> <h1>In practice on Android</h1> <p> The Android team began prioritizing transitioning new development to memory safe languages around 2019. This decision was driven by the increasing cost and complexity of managing memory safety vulnerabilities. There’s much left to do, but the results have already been positive. Here’s the big picture in 2024, looking at total code: <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1OlXyuvF9q6o3VG9Rh4OSgrEvvlJZ0D_O5uW5lp-NhF8hSxDkY98ftEfwYvFQrAGp-ftnehqJ2RU17KDyfhgI3KjeFsmJyqGmL7n_Ip1SXAnza-NSqgrsJ47HOTluyzKAb_LCpwGHtVybKg9LNgRorEKWS2LIpqrnmcPIxLRPfW9ECK_XqSQ5fjrU2WhH/s1600/image5.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1OlXyuvF9q6o3VG9Rh4OSgrEvvlJZ0D_O5uW5lp-NhF8hSxDkY98ftEfwYvFQrAGp-ftnehqJ2RU17KDyfhgI3KjeFsmJyqGmL7n_Ip1SXAnza-NSqgrsJ47HOTluyzKAb_LCpwGHtVybKg9LNgRorEKWS2LIpqrnmcPIxLRPfW9ECK_XqSQ5fjrU2WhH/s1600/image5.png"/></a></div> <p> <br> </p> <p> Despite the majority of code still being unsafe (but, crucially, getting progressively older), we’re seeing a large and continued decline in memory safety vulnerabilities. The results align with what we simulated above, and are even better, potentially as a result of our parallel efforts to improve the safety of our memory unsafe code. We first <a href="https://security.googleblog.com/2022/12/memory-safe-languages-in-android-13.html">reported</a> this decline in 2022, and we continue to see the total number of memory safety vulnerabilities dropping<sup id="fnref3"><a href="#fn3" rel="footnote">3</a></sup>. Note that the data for 2024 is extrapolated to the full year (represented as 36, but currently at 27 after the <a href="https://source.android.com/docs/security/bulletin/2024-09-01">September security bulletin</a>). <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilTxSxGJLA-FakEzfrwOMTFJ8S03bJDn6Y61pKhtEAYV0oGXi1T_kVL48uU0ojZD9IwSXIQKL-duOtU1m4uEMsxNpvC3U9N_aynQ1XkrIkyFNve9Zj3FlbxJgcdrZaCSeKKJhYpEQM_NiMQDZduorxc8hgNJccpTX_VX3XYYV3uaQCwny7duVVDMNAHWHp/s1600/image8.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilTxSxGJLA-FakEzfrwOMTFJ8S03bJDn6Y61pKhtEAYV0oGXi1T_kVL48uU0ojZD9IwSXIQKL-duOtU1m4uEMsxNpvC3U9N_aynQ1XkrIkyFNve9Zj3FlbxJgcdrZaCSeKKJhYpEQM_NiMQDZduorxc8hgNJccpTX_VX3XYYV3uaQCwny7duVVDMNAHWHp/s1600/image8.png"/></a></div> </p> <p> The percent of vulnerabilities caused by memory safety issues continues to correlate closely with the development language that’s used for new code. Memory safety issues, which accounted for 76% of Android vulnerabilities in 2019, and are currently 24% in 2024, well below the 70% industry norm, and continuing to drop. <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoFvbQ1AN4OQOiRSBNqRKGhHAsaJNSJNOQ9ixLn0ClESW2S_zQttsaTuPY06gvxrY2d9QUUCoWNFzypHX6RB4mhOyhM8fbjJjDL6uascUpVYl7hgisMWcc0lcKRrWCPKc7XXoIxzj_Hr-7nOF6N3glP05w0wsvfdGmAENLha8yZYL7mPOmPqg1Q187oiQi/s1600/image6.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="742" data-original-width="1200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoFvbQ1AN4OQOiRSBNqRKGhHAsaJNSJNOQ9ixLn0ClESW2S_zQttsaTuPY06gvxrY2d9QUUCoWNFzypHX6RB4mhOyhM8fbjJjDL6uascUpVYl7hgisMWcc0lcKRrWCPKc7XXoIxzj_Hr-7nOF6N3glP05w0wsvfdGmAENLha8yZYL7mPOmPqg1Q187oiQi/s1600/image6.png"/></a></div> </p> <p> As we noted in a <a href="https://security.googleblog.com/2022/12/memory-safe-languages-in-android-13.html">previous post, </a>memory safety vulnerabilities tend to be significantly more severe, more likely to be remotely reachable, more versatile, and more likely to be maliciously exploited than other vulnerability types. As the number of memory safety vulnerabilities have dropped, the overall security risk has dropped along with it. </p> <h1>Evolution of memory safety strategies</h1> <p> Over the past decades, the industry has pioneered significant advancements to combat memory safety vulnerabilities, with each generation of advancements contributing valuable tools and techniques that have tangibly improved software security. However, with the benefit of hindsight, it’s evident that we have yet to achieve a truly scalable and sustainable solution that achieves an acceptable level of risk: </p> <p> <strong>1st generation: reactive patching.</strong> The initial focus was mainly on fixing vulnerabilities reactively. For problems as rampant as memory safety, this incurs ongoing costs on the business and its users. Software manufacturers have to invest significant resources in responding to frequent incidents. This leads to constant security updates, leaving users vulnerable to unknown issues, and frequently albeit temporarily vulnerable to known issues, which are getting exploited <a href="https://cloud.google.com/blog/topics/threat-intelligence/time-to-exploit-trends-2021-2022/">ever faster</a>. </p> <p> <strong>2nd generation: proactive mitigating. </strong>The next approach consisted of reducing risk in vulnerable software, including a series of exploit mitigation strategies that raised the costs of crafting exploits. However, these mitigations, such as stack canaries and control-flow integrity, typically impose a recurring cost on products and development teams, often putting security and other product requirements in conflict: </p> <ul> <li>They come with performance overhead, impacting execution speed, battery life, tail latencies, and memory usage, sometimes preventing their deployment. <li>Attackers are seemingly infinitely creative, resulting in a cat-and-mouse game with defenders. In addition, the bar to develop and weaponize an exploit is regularly being lowered through <a href="https://docs.pwntools.com/en/stable/">better tooling</a> and other <a href="https://googleprojectzero.blogspot.com/2024/06/project-naptime.html">advancements</a>. </li> </ul> <p> <strong>3rd generation: proactive vulnerability discovery.</strong> The following generation focused on detecting vulnerabilities. This includes <a href="https://github.com/google/sanitizers">sanitizers</a>, often paired with fuzzing like <a href="https://llvm.org/docs/LibFuzzer.html">libfuzzer</a>, many of which were built by Google. While helpful, these methods address the symptoms of memory unsafety, not the root cause. They typically require constant pressure to get teams to fuzz, triage, and fix their findings, resulting in low coverage. Even when applied thoroughly, fuzzing does not provide high assurance, as evidenced by vulnerabilities found in extensively fuzzed code. </p> <p> Products across the industry have been significantly strengthened by these approaches, and we remain committed to responding to, mitigating, and proactively hunting for vulnerabilities. Having said that, it has become increasingly clear that those approaches are not only insufficient for reaching an acceptable level of risk in the memory-safety domain, but incur ongoing and increasing costs to developers, users, businesses, and products. As highlighted by numerous government agencies, including CISA, in their <a href="https://www.cisa.gov/sites/default/files/2023-10/SecureByDesign_1025_508c.pdf">secure-by-design report</a>, "only by incorporating secure by design practices will we break the vicious cycle of constantly creating and applying fixes." </p> <h1>The fourth generation: high-assurance prevention</h1> <p> The shift towards memory safe languages represents more than just a change in technology, it is a fundamental shift in how to approach security. This shift is not an unprecedented one, but rather a significant expansion of a proven approach. An approach that has already demonstrated remarkable <a href="https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/42934.pdf">success</a> in eliminating other vulnerability classes like XSS. </p> <p> The foundation of this shift is <a href="https://dl.acm.org/doi/10.1145/3651621">Safe Coding</a>, which enforces security invariants directly into the development platform through language features, static analysis, and API design. The result is a secure by design ecosystem providing continuous assurance at scale, safe from the risk of accidentally introducing vulnerabilities. </p> <p> The shift from previous generations to Safe Coding can be seen in the quantifiability of the assertions that are made when developing code. Instead of focusing on the interventions applied (mitigations, fuzzing), or attempting to use past performance to predict future security, Safe Coding allows us to make strong assertions about the code's properties and what can or cannot happen based on those properties. </p> <p> Safe Coding's scalability lies in its ability to reduce costs by: </p> <ul> <li><strong>Breaking the arms race:</strong> Instead of an endless arms race of defenders attempting to raise attackers’ costs by also raising their own, Safe Coding leverages our control of developer ecosystems to break this cycle by focusing on proactively building secure software from the start. <li><strong>Commoditizing high assurance memory safety:</strong> Rather than precisely tailoring interventions to each asset's assessed risk, all while managing the cost and overhead of reassessing evolving risks and applying disparate interventions, Safe Coding establishes a <a href="https://www.philvenables.com/post/raise-the-baseline-by-reducing-the-cost-of-control">high baseline of commoditized security</a>, like memory-safe languages, that affordably reduces vulnerability density across the board. Modern memory-safe languages (especially Rust) extend these principles beyond memory safety to other bug classes. <li><strong>Increasing productivity</strong>: Safe Coding improves code correctness and developer productivity by shifting bug finding further left, before the code is even checked in. We see this shift showing up in important metrics such as rollback rates (emergency code revert due to an unanticipated bug). The Android team has observed that the rollback rate of Rust changes is less than half that of C++. </li> </ul> <h1>From lessons to action</h1> <h2>Interoperability is the new rewrite</h2> <p> Based on what we’ve learned, it's become clear that we do not need to throw away or rewrite all our existing memory-unsafe code. Instead, Android is focusing on making interoperability safe and convenient as a primary capability in our memory safety journey. Interoperability offers a practical and incremental approach to adopting memory safe languages, allowing organizations to leverage existing investments in code and systems, while accelerating the development of new features. </p> <p> We recommend focusing investments on improving interoperability, as we are doing with Rust ↔︎ C++ and Rust ↔︎ <a href="https://github.com/rust-diplomat/diplomat/pull/629">Kotlin</a>. To that end, earlier this year, Google provided a <a href="https://security.googleblog.com/2024/02/improving-interoperability-between-rust-and-c.html">$1,000,000 grant</a> to the Rust Foundation, in addition to developing interoperability tooling like <a href="https://github.com/google/crubit">Crubit</a> and <a href="https://github.com/google/autocxx">autocxx</a>. </p> <h2>Role of previous generations</h2> <p> As Safe Coding continues to drive down risk, what will be the role of mitigations and proactive detection? We don’t have definitive answers in Android, but expect something like the following: </p> <ul> <li><strong>More selective use of proactive mitigations</strong>: We expect less reliance on exploit mitigations as we transition to memory-safe code, leading to not only safer software, but also more efficient software. For instance, after removing the now unnecessary sandbox, <a href="https://groups.google.com/a/chromium.org/g/chromium-dev/c/UhwVDk4HZFA">Chromium's Rust QR code generator</a> is 20 times faster. <li><strong>Decreased use, but increased effectiveness of proactive detection</strong>: We anticipate a decreased reliance on proactive detection approaches like fuzzing, but increased effectiveness, as achieving comprehensive coverage over small well-encapsulated code snippets becomes more feasible. </li> </ul> <h1>Final thoughts</h1> <p> Fighting against the math of vulnerability lifetimes has been a losing battle. Adopting Safe Coding in new code offers a paradigm shift, allowing us to leverage the inherent decay of vulnerabilities to our advantage, <em>even in large existing systems</em>. The concept is simple: once we turn off the tap of new vulnerabilities, they decrease exponentially, making all of our code safer, increasing the <a href="https://docs.google.com/presentation/d/16LZ6T-tcjgp3T8_N3m0pa5kNA1DwIsuMcQYDhpMU7uU/edit#slide=id.g3e7cac054a_0_89">effectiveness of security design</a>, and alleviating the scalability challenges associated with existing memory safety strategies such that they can be applied more effectively in a targeted manner. </p> <p> This approach has proven successful in eliminating entire vulnerability classes and its effectiveness in tackling memory safety is increasingly evident based on more than half a decade of consistent results in Android. </p> <p> We'll be sharing more about our secure-by-design efforts in the coming months. </p> <h1>Acknowledgements</h1> <p> Thanks Alice Ryhl for coding up the simulation. Thanks to Emilia Kasper, Adrian Taylor, Manish Goregaokar, Christoph Kern, and Lars Bergstrom for your helpful feedback on this post. </p>  <h2>Notes</h2> <div class="footnotes"> <hr> <ol><li id="fn1"> <p> Simulation was based on numbers similar to Android and other Google projects. The code base doubles every 6 years. The average lifetime for vulnerabilities is 2.5 years. It takes 10 years to transition to memory safe languages for new code, and we use a sigmoid function to represent the transition. Note that the use of the sigmoid function is why the second chart doesn’t initially appear to be exponential. <a href="#fnref1" rev="footnote">↩</a><li id="fn2"> <p> Alexopoulos et al. <a href="https://www.usenix.org/conference/usenixsecurity22/presentation/alexopoulos">"How Long Do Vulnerabilities Live in the Code? A Large-Scale Empirical Measurement Study on FOSS Vulnerability Lifetimes"</a>. USENIX Security 22. <a href="#fnref2" rev="footnote">↩</a><li id="fn3"> <p> Unlike our simulation, these are vulnerabilities from a real code base, which comes with higher variance, as you can see in the slight increase in 2023. Vulnerability reports were unusually high that year, but in line with expectations given code growth, so while the percentage of memory safety vulnerabilities continued to drop, the absolute number increased slightly. <a href="#fnref3" rev="footnote">↩</a> </ol></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:Eliminating Memory Safety Vulnerabilities at the Source&url=https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html' data-url='https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/09/eliminating-memory-safety-vulnerabilities-Android.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> </span> </div> </div> </div> <div class='post' data-id='5763420481971967949' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html' itemprop='url' title='Google & Arm - Raising The Bar on GPU Security'> Google & Arm - Raising The Bar on GPU Security </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> September 24, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <span class="byline-author">Posted by Xuan Xing, Eugene Rodionov, Jon Bottarini, Adam Bacchus - Android Red Team; Amit Chaudhary, Lyndon Fawcett, Joseph Artgole - Arm Product Security Team </span> <h3>Who cares about GPUs?</h3> <p> You, me, and the entire ecosystem! GPUs (graphics processing units) are critical in delivering rich visual experiences on mobile devices. However, the GPU software and firmware stack has become a way for attackers to gain permissions and entitlements (privilege escalation) to Android-based devices. There are plenty of issues in this category that can affect all major GPU brands, for example, <a href="https://nvd.nist.gov/vuln/detail/CVE-2023-4295">CVE-2023-4295</a>, <a href="https://nvd.nist.gov/vuln/detail/CVE-2023-21106">CVE-2023-21106</a>, <a href="https://nvd.nist.gov/vuln/detail/CVE-2021-0884">CVE-2021-0884</a>, and more. Most exploitable GPU vulnerabilities are in the implementation of the GPU kernel mode modules. These modules are pieces of code that load/unload during runtime, extending functionality without the need to reboot the device. </p> <p> Proactive testing is good hygiene as it can lead to the detection and resolution of new vulnerabilities before they’re exploited. It’s also one of the most complex investigations to do as you don’t necessarily know where the vulnerability will appear (that’s the point!). By combining the expertise of Google’s engineers with IP owners and OEMs, we can ensure the Android ecosystem retains a strong measure of integrity. </p> <h3>Why investigate GPUs?</h3> <p> When researching vulnerabilities, GPUs are a popular target due to: </p> <ol> <li><strong>Functionality vs. Security Tradeoffs</strong> <p> Nobody wants a slow, unresponsive device; any hits to GPU performance could result in a noticeably degraded user experience. As such, the GPU software stack in Android relies on an <strong>in-process HAL model</strong> where the API & user space drivers communicating with the GPU kernel mode module are running directly within the context of apps, thus avoiding IPC (interprocess communication). This opens the door for potentially untrusted code from a third party app being able to directly access the interface exposed by the GPU kernel module. If there are any vulnerabilities in the module, the third party app has an avenue to exploit them. As a result, a potentially untrusted code running in the context of the third party application is able to directly access the interface exposed by the GPU kernel module and exploit potential vulnerabilities in the kernel module. </p> <p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVb2Z92K3Iu0Eouk9WRIelR9flB1_0IJU1_HBpg-fJuuc3HUZen3aDt1P_C_JkSSqhEPSk6ivro3DVZwi1NXTBszbOSLKVzzU103x-c9EFryOUc71iWkl1JK2oHPC6R2M3-jFdWQfEiOQxYsl9bL2XWputk8mTpmHaG17BQIMhLM-Wj2xOnWy5un9qzP6G/s1600/arm%20blog.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="648" data-original-width="861" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVb2Z92K3Iu0Eouk9WRIelR9flB1_0IJU1_HBpg-fJuuc3HUZen3aDt1P_C_JkSSqhEPSk6ivro3DVZwi1NXTBszbOSLKVzzU103x-c9EFryOUc71iWkl1JK2oHPC6R2M3-jFdWQfEiOQxYsl9bL2XWputk8mTpmHaG17BQIMhLM-Wj2xOnWy5un9qzP6G/s1600/arm%20blog.png"/></a></div> <li><strong>Variety & Memory Safety</strong> <p> Additionally, the implementation of GPU subsystems (and kernel modules specifically) from major OEMs are increasingly complex. Kernel modules for most GPUs are typically written in memory unsafe languages such as C, which are susceptible to memory corruption vulnerabilities like buffer overflow. </p> </li> </ol> <h3>Can someone do something about this?</h3> <p> Great news, we already have! Who’s we? The Android Red Team and Arm! We’ve worked together to run an engagement on the Mali GPU (more on that below), but first, a brief introduction: </p> <p> <strong>Android Red Team</strong> </p> <p> The Android Red Team performs time-bound security assessment engagements on all aspects of the Android open source codebase and conducts regular security reviews and assessments of internal Android components. Throughout these engagements, the Android Red Team regularly collaborates with 3rd party software and hardware providers to analyze and understand proprietary and “closed source” code repositories and relevant source code that are utilized by Android products with the sole objective to identify security risks and potential vulnerabilities before they can be exploited by adversaries outside of Android. This year, the Android Red Team collaborated directly with our industry partner, Arm, to conduct the Mali GPU engagement and further secure millions of Android devices. </p> <p> <strong>Arm Product Security and GPU Teams</strong> </p> <p> Arm has a central product security team that sets the policy and practice across the company. They also have dedicated product security experts embedded in engineering teams. Arm operates a systematic approach which is designed to prevent, discover, and eliminate security vulnerabilities. This includes a Security Development Lifecycle (SDL), a Monitoring capability, and Incident Response. For this collaboration the Android Red Teams were supported by the embedded security experts based in Arm’s GPU engineering team. </p> <h3>Working together to secure Android devices</h3> <p> Google’s Android Security teams and Arm have been working together for a long time. Security requirements are never static, and challenges exist with all GPU vendors. By frequently sharing expertise, the Android Red Team and Arm were able to accelerate detection and resolution. Investigations of identified vulnerabilities, potential remediation strategies, and hardening measures drove detailed analyses and the implementation of fixes where relevant. </p> <p> Recent research focused on the Mali GPU because it is the most popular GPU in today's Android devices. Collaborating on GPU security allowed us to: </p> <ol> <li><strong>Assess the impact on the broadest segment of the Android Ecosystem</strong>: The Arm Mali GPU is one of the most used GPUs by original equipment manufacturers (OEMs) and is found in many popular mobile devices. By focusing on the Arm Mali GPU, the Android Red Team could assess the security of a GPU implementation running on millions of Android devices worldwide. <li><strong>Evaluate the reference implementation and vendor-specific changes: </strong>Phone manufacturers often modify the upstream implementation of GPUs. This tailors the GPU to the manufacturer's specific device(s). These modifications and enhancements are always challenging to make, and can sometimes introduce security vulnerabilities that are not present in the original version of the GPU upstream. In this specific instance, the Google Pixel team actively worked with the Android Red Team to better understand and secure the modifications they made for Pixel devices. </li> </ol> <h3>Improvements</h3> <p> Investigations have led to significant improvements, leveling up the security of the GPU software/firmware stack across a wide segment of the Android ecosystem. </p> <h2>Testing the kernel driver</h2> <p> One key component of the GPU subsystem is its kernel mode driver. During this engagement, both the Android Red Team and Arm invested significant effort looking at the Mali kbase kernel driver. Due to its complexity, fuzzing was chosen as the primary testing approach for this area. Fuzzing automates and scales vulnerability discovery in a way not possible via manual methods. With help from Arm, the Android Red Team added more syzkaller fuzzing descriptions to match the latest Mali kbase driver implementation. </p> <p> The team built a few customizations to enable fuzzing the Mali kbase driver in the cloud, without physical hardware. This provided a huge improvement to fuzzing performance and scalability. With the Pixel team’s support, we also were able to set up fuzzing on actual Pixel devices. Through the combination of cloud-based fuzzing, Pixel-based fuzzing, and manual review, we were able to uncover two memory issues in Pixel’s customization of driver code (CVE-2023-48409 and CVE-2023-48421). </p> <p> Both issues occurred inside of the gpu_pixel_handle_buffer_liveness_update_ioctl function, which is implemented by the Pixel team as part of device specific customization. These are both memory issues caused by integer overflow problems. If exploited carefully alongside other vulnerabilities, these issues could lead to kernel privilege escalation from user space. Both issues were fixed and the patch was released to affected devices in <a href="https://source.android.com/docs/security/bulletin/pixel/2023-12-01">Pixel security bulletin 2023-12-01</a>. </p> <h2>Testing the firmware</h2> <p> Firmware is another fundamental building block of the GPU subsystem. It’s the intermediary working with kernel drivers and GPU hardware. In many cases, firmware functionality is directly/indirectly accessible from the application. So “application ⇒ kernel ⇒ firmware ⇒ kernel” is a known attack flow in this area. Also, in general, firmware runs on embedded microcontrollers with limited resources. Commonly used security kernel mitigations (ASLR, stack protection, heap protection, certain sanitizers, etc.) might not be applicable to firmware due to resource constraints and performance impact. This can make compromising firmware easier, in some cases, than directly compromising kernel drivers from user space. To test the integrity of existing firmware, the Android Red Team and Arm worked together to perform both fuzzing and formal verification along with manual analysis. This multi-pronged approach led to the discovery of CVE-2024-0153, which had a patch released in <a href="https://source.android.com/docs/security/bulletin/2024-07-01">the July 2024 Android Security Bulletin</a>. </p> <p> CVE-2024-0153 happens when GPU firmware handles certain instructions. When handling such instructions, the firmware copies register content into a buffer. There are size checks before the copy operation. However, under very specific conditions, an out-of-bounds write happens to the destination buffer, leading to a buffer overflow. When carefully manipulated, this overflow will overwrite some other important structures following the buffer, causing code execution inside of the GPU firmware. </p> <p> The conditions necessary to reach and potentially exploit this issue are very complex as it requires a deep understanding of how instructions are executed. With collective expertise, the Android Red Team and Arm were able to verify the exploitation path and leverage the issue to gain limited control of GPU firmware. This eventually circled back to the kernel to obtain privilege escalation. Arm did an excellent job to respond quickly and remediate the issue. Altogether, this highlights the strength of collaboration between both teams to dive deeper. </p> <h3>Time to Patch</h3> <p> It’s known that attackers exploit GPU vulnerabilities in the wild, and time to patch is crucial to reduce risk of exploitation and protect users. As a result of this engagement, nine new Security Test suite (<a href="https://source.android.com/docs/security/test/sts-sdk">STS</a>) tests were built to help partners automatically check their builds for missing Mali kbase patches. (Security Test Suite is software provided by Google to help partners automate the process of checking their builds for missing security patches.) </p> <h3>What’s Next?</h3> <p> The Arm Product Security Team is actively involved in security-focused industry communities and collaborates closely with its ecosystem partners. The engagement with the Android Red Team, for instance, provides valuable enablement that drives best practices and product excellence. Building on this collaborative approach, Arm is complementing its product security assurance capabilities with a bug bounty program. This investment will expand Arm’s efforts to identify potential vulnerabilities. For more information on Arm's product security initiatives, please visit this <a href="https://www.arm.com/products/product-security" target="_blank">product security page</a>. </p> <p> The Android Red Team and Arm continue to work together to proactively raise the bar on GPU security. With thorough testing, rapid fixing, and updates to the security test suite, we’re improving the ecosystem for Android users. The Android Red Team looks forward to replicating this working relationship with other ecosystem partners to make devices more secure. </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <span class="byline-author">Posted by Xuan Xing, Eugene Rodionov, Jon Bottarini, Adam Bacchus - Android Red Team; Amit Chaudhary, Lyndon Fawcett, Joseph Artgole - Arm Product Security Team </span> <h3>Who cares about GPUs?</h3> <p> You, me, and the entire ecosystem! GPUs (graphics processing units) are critical in delivering rich visual experiences on mobile devices. However, the GPU software and firmware stack has become a way for attackers to gain permissions and entitlements (privilege escalation) to Android-based devices. There are plenty of issues in this category that can affect all major GPU brands, for example, <a href="https://nvd.nist.gov/vuln/detail/CVE-2023-4295">CVE-2023-4295</a>, <a href="https://nvd.nist.gov/vuln/detail/CVE-2023-21106">CVE-2023-21106</a>, <a href="https://nvd.nist.gov/vuln/detail/CVE-2021-0884">CVE-2021-0884</a>, and more. Most exploitable GPU vulnerabilities are in the implementation of the GPU kernel mode modules. These modules are pieces of code that load/unload during runtime, extending functionality without the need to reboot the device. </p> <p> Proactive testing is good hygiene as it can lead to the detection and resolution of new vulnerabilities before they’re exploited. It’s also one of the most complex investigations to do as you don’t necessarily know where the vulnerability will appear (that’s the point!). By combining the expertise of Google’s engineers with IP owners and OEMs, we can ensure the Android ecosystem retains a strong measure of integrity. </p> <h3>Why investigate GPUs?</h3> <p> When researching vulnerabilities, GPUs are a popular target due to: </p> <ol> <li><strong>Functionality vs. Security Tradeoffs</strong> <p> Nobody wants a slow, unresponsive device; any hits to GPU performance could result in a noticeably degraded user experience. As such, the GPU software stack in Android relies on an <strong>in-process HAL model</strong> where the API & user space drivers communicating with the GPU kernel mode module are running directly within the context of apps, thus avoiding IPC (interprocess communication). This opens the door for potentially untrusted code from a third party app being able to directly access the interface exposed by the GPU kernel module. If there are any vulnerabilities in the module, the third party app has an avenue to exploit them. As a result, a potentially untrusted code running in the context of the third party application is able to directly access the interface exposed by the GPU kernel module and exploit potential vulnerabilities in the kernel module. </p> <p> <div class="separator" style="clear: both;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVb2Z92K3Iu0Eouk9WRIelR9flB1_0IJU1_HBpg-fJuuc3HUZen3aDt1P_C_JkSSqhEPSk6ivro3DVZwi1NXTBszbOSLKVzzU103x-c9EFryOUc71iWkl1JK2oHPC6R2M3-jFdWQfEiOQxYsl9bL2XWputk8mTpmHaG17BQIMhLM-Wj2xOnWy5un9qzP6G/s1600/arm%20blog.png" style="display: block; padding: 1em 0; text-align: center; "><img alt="" border="0" data-original-height="648" data-original-width="861" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVb2Z92K3Iu0Eouk9WRIelR9flB1_0IJU1_HBpg-fJuuc3HUZen3aDt1P_C_JkSSqhEPSk6ivro3DVZwi1NXTBszbOSLKVzzU103x-c9EFryOUc71iWkl1JK2oHPC6R2M3-jFdWQfEiOQxYsl9bL2XWputk8mTpmHaG17BQIMhLM-Wj2xOnWy5un9qzP6G/s1600/arm%20blog.png"/></a></div> <li><strong>Variety & Memory Safety</strong> <p> Additionally, the implementation of GPU subsystems (and kernel modules specifically) from major OEMs are increasingly complex. Kernel modules for most GPUs are typically written in memory unsafe languages such as C, which are susceptible to memory corruption vulnerabilities like buffer overflow. </p> </li> </ol> <h3>Can someone do something about this?</h3> <p> Great news, we already have! Who’s we? The Android Red Team and Arm! We’ve worked together to run an engagement on the Mali GPU (more on that below), but first, a brief introduction: </p> <p> <strong>Android Red Team</strong> </p> <p> The Android Red Team performs time-bound security assessment engagements on all aspects of the Android open source codebase and conducts regular security reviews and assessments of internal Android components. Throughout these engagements, the Android Red Team regularly collaborates with 3rd party software and hardware providers to analyze and understand proprietary and “closed source” code repositories and relevant source code that are utilized by Android products with the sole objective to identify security risks and potential vulnerabilities before they can be exploited by adversaries outside of Android. This year, the Android Red Team collaborated directly with our industry partner, Arm, to conduct the Mali GPU engagement and further secure millions of Android devices. </p> <p> <strong>Arm Product Security and GPU Teams</strong> </p> <p> Arm has a central product security team that sets the policy and practice across the company. They also have dedicated product security experts embedded in engineering teams. Arm operates a systematic approach which is designed to prevent, discover, and eliminate security vulnerabilities. This includes a Security Development Lifecycle (SDL), a Monitoring capability, and Incident Response. For this collaboration the Android Red Teams were supported by the embedded security experts based in Arm’s GPU engineering team. </p> <h3>Working together to secure Android devices</h3> <p> Google’s Android Security teams and Arm have been working together for a long time. Security requirements are never static, and challenges exist with all GPU vendors. By frequently sharing expertise, the Android Red Team and Arm were able to accelerate detection and resolution. Investigations of identified vulnerabilities, potential remediation strategies, and hardening measures drove detailed analyses and the implementation of fixes where relevant. </p> <p> Recent research focused on the Mali GPU because it is the most popular GPU in today's Android devices. Collaborating on GPU security allowed us to: </p> <ol> <li><strong>Assess the impact on the broadest segment of the Android Ecosystem</strong>: The Arm Mali GPU is one of the most used GPUs by original equipment manufacturers (OEMs) and is found in many popular mobile devices. By focusing on the Arm Mali GPU, the Android Red Team could assess the security of a GPU implementation running on millions of Android devices worldwide. <li><strong>Evaluate the reference implementation and vendor-specific changes: </strong>Phone manufacturers often modify the upstream implementation of GPUs. This tailors the GPU to the manufacturer's specific device(s). These modifications and enhancements are always challenging to make, and can sometimes introduce security vulnerabilities that are not present in the original version of the GPU upstream. In this specific instance, the Google Pixel team actively worked with the Android Red Team to better understand and secure the modifications they made for Pixel devices. </li> </ol> <h3>Improvements</h3> <p> Investigations have led to significant improvements, leveling up the security of the GPU software/firmware stack across a wide segment of the Android ecosystem. </p> <h2>Testing the kernel driver</h2> <p> One key component of the GPU subsystem is its kernel mode driver. During this engagement, both the Android Red Team and Arm invested significant effort looking at the Mali kbase kernel driver. Due to its complexity, fuzzing was chosen as the primary testing approach for this area. Fuzzing automates and scales vulnerability discovery in a way not possible via manual methods. With help from Arm, the Android Red Team added more syzkaller fuzzing descriptions to match the latest Mali kbase driver implementation. </p> <p> The team built a few customizations to enable fuzzing the Mali kbase driver in the cloud, without physical hardware. This provided a huge improvement to fuzzing performance and scalability. With the Pixel team’s support, we also were able to set up fuzzing on actual Pixel devices. Through the combination of cloud-based fuzzing, Pixel-based fuzzing, and manual review, we were able to uncover two memory issues in Pixel’s customization of driver code (CVE-2023-48409 and CVE-2023-48421). </p> <p> Both issues occurred inside of the gpu_pixel_handle_buffer_liveness_update_ioctl function, which is implemented by the Pixel team as part of device specific customization. These are both memory issues caused by integer overflow problems. If exploited carefully alongside other vulnerabilities, these issues could lead to kernel privilege escalation from user space. Both issues were fixed and the patch was released to affected devices in <a href="https://source.android.com/docs/security/bulletin/pixel/2023-12-01">Pixel security bulletin 2023-12-01</a>. </p> <h2>Testing the firmware</h2> <p> Firmware is another fundamental building block of the GPU subsystem. It’s the intermediary working with kernel drivers and GPU hardware. In many cases, firmware functionality is directly/indirectly accessible from the application. So “application ⇒ kernel ⇒ firmware ⇒ kernel” is a known attack flow in this area. Also, in general, firmware runs on embedded microcontrollers with limited resources. Commonly used security kernel mitigations (ASLR, stack protection, heap protection, certain sanitizers, etc.) might not be applicable to firmware due to resource constraints and performance impact. This can make compromising firmware easier, in some cases, than directly compromising kernel drivers from user space. To test the integrity of existing firmware, the Android Red Team and Arm worked together to perform both fuzzing and formal verification along with manual analysis. This multi-pronged approach led to the discovery of CVE-2024-0153, which had a patch released in <a href="https://source.android.com/docs/security/bulletin/2024-07-01">the July 2024 Android Security Bulletin</a>. </p> <p> CVE-2024-0153 happens when GPU firmware handles certain instructions. When handling such instructions, the firmware copies register content into a buffer. There are size checks before the copy operation. However, under very specific conditions, an out-of-bounds write happens to the destination buffer, leading to a buffer overflow. When carefully manipulated, this overflow will overwrite some other important structures following the buffer, causing code execution inside of the GPU firmware. </p> <p> The conditions necessary to reach and potentially exploit this issue are very complex as it requires a deep understanding of how instructions are executed. With collective expertise, the Android Red Team and Arm were able to verify the exploitation path and leverage the issue to gain limited control of GPU firmware. This eventually circled back to the kernel to obtain privilege escalation. Arm did an excellent job to respond quickly and remediate the issue. Altogether, this highlights the strength of collaboration between both teams to dive deeper. </p> <h3>Time to Patch</h3> <p> It’s known that attackers exploit GPU vulnerabilities in the wild, and time to patch is crucial to reduce risk of exploitation and protect users. As a result of this engagement, nine new Security Test suite (<a href="https://source.android.com/docs/security/test/sts-sdk">STS</a>) tests were built to help partners automatically check their builds for missing Mali kbase patches. (Security Test Suite is software provided by Google to help partners automate the process of checking their builds for missing security patches.) </p> <h3>What’s Next?</h3> <p> The Arm Product Security Team is actively involved in security-focused industry communities and collaborates closely with its ecosystem partners. The engagement with the Android Red Team, for instance, provides valuable enablement that drives best practices and product excellence. Building on this collaborative approach, Arm is complementing its product security assurance capabilities with a bug bounty program. This investment will expand Arm’s efforts to identify potential vulnerabilities. For more information on Arm's product security initiatives, please visit this <a href="https://www.arm.com/products/product-security" target="_blank">product security page</a>. </p> <p> The Android Red Team and Arm continue to work together to proactively raise the bar on GPU security. With thorough testing, rapid fixing, and updates to the security test suite, we’re improving the ecosystem for Android users. The Android Red Team looks forward to replicating this working relationship with other ecosystem partners to make devices more secure. </p> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </noscript> </div> </div> <div class='share'> <span class='twitter-custom social-wrapper' data-href='http://twitter.com/share?text=Google Online Security Blog:Google & Arm - Raising The Bar on GPU Security&url=https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html&via=google'> <img alt='Share on Twitter' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_twitter_black_24dp.png' width='24'/> </span> <span class='fb-custom social-wrapper' data-href='https://www.facebook.com/sharer.php?u=https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html'> <img alt='Share on Facebook' height='24' src='https://www.gstatic.com/images/icons/material/system/2x/post_facebook_black_24dp.png' width='24'/> </span> </div> <div class='comment-container'> <i class='comment-img material-icons'>  </i> <span class='cmt_count_iframe_holder' data-count='0' data-onclick='javascript:window.open(this.href, "bloggerPopup", "toolbar=0,location=0,statusbar=1,menubar=0,scrollbars=yes,width=640,height=500"); return false;' data-post-url='https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html' data-url='https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html' style='color: #4184F3;'></span> </div> <div class='post-footer'> <div class='cmt_iframe_holder' data-href='https://security.googleblog.com/2024/09/google-arm-raising-bar-on-gpu-security.html' data-viewtype='FILTERED_POSTMOD'></div> <a href='https://plus.google.com/112374322230920073195' rel='author' style='display:none;'> Google </a> <div class='label-footer'> <span class='labels-caption'> Labels: </span> <span class='labels'> <a class='label' href='https://security.googleblog.com/search/label/android' rel='tag'> android </a> , <a class='label' href='https://security.googleblog.com/search/label/android%20security' rel='tag'> android security </a> , <a class='label' href='https://security.googleblog.com/search/label/pixel' rel='tag'> pixel </a> </span> </div> </div> </div> <div class='post' data-id='981209424551816912' itemscope='' itemtype='http://schema.org/BlogPosting'> <h2 class='title' itemprop='name'> <a href='https://security.googleblog.com/2024/09/deploying-rust-in-existing-firmware.html' itemprop='url' title='Deploying Rust in Existing Firmware Codebases'> Deploying Rust in Existing Firmware Codebases </a> </h2> <div class='post-header'> <div class='published'> <span class='publishdate' itemprop='datePublished'> September 4, 2024 </span> </div> </div> <div class='post-body'> <div class='post-content' itemprop='articleBody'> <script type='text/template'> <p style="text-align: left;"><span class="byline-author">Posted by Ivan Lozano and Dominik Maier, Android Team</span> <p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Android's use of safe-by-design principles drives our adoption of memory-safe languages like Rust, making exploitation of the OS increasingly difficult with every release. To provide a secure foundation, we’re extending hardening and the use of </span><a href="https://security.googleblog.com/2023/10/bare-metal-rust-in-android.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">memory-safe languages to low-level firmware</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (including in </span><a href="https://cs.android.com/android/platform/superproject/main/+/main:trusty/user/app/keymint/lib.rs;drc=4176f2465d7dc81c398730cb579c0a4949a9a832" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Trusty apps</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">).</span></p><br /><p dir="ltr" style="line-height: 1.3800000000000001; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In this blog post, we'll show you how to gradually introduce </span><a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html#:~:text=But%20what%20about%20all%20that%20existing%20C%2B%2B%3F" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust into your existing firmware</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, prioritizing new code and the most security-critical code. You'll see how easy it is to boost security with drop-in Rust replacements, and we'll even demonstrate how the Rust toolchain can handle specialized bare-metal targets.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Drop-in Rust replacements for C code are not a novel idea and have been used in other cases, such as </span><a href="https://mail.gnome.org/archives/desktop-devel-list/2017-January/msg00001.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">librsvg’s adoption of Rust</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> which involved </span><a href="https://web.archive.org/web/20170928062853/https://people.gnome.org/~federico/blog/docs/fmq-porting-c-to-rust.pdf" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">replacing C functions with Rust functions</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> in-place. We seek to demonstrate that this approach is viable for firmware, providing a path to memory-safety in an efficient and effective manner.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Memory Safety for Firmware</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Firmware serves as the interface between hardware and higher-level software. Due to the lack of software security mechanisms that are standard in higher-level software, vulnerabilities in firmware code can be dangerously exploited by malicious actors. Modern phones contain many coprocessors responsible for handling various operations, and each of these run their own firmware. Often, firmware consists of large legacy code bases written in memory-unsafe languages such as C or C++. Memory unsafety is the leading cause of vulnerabilities in </span><a href="https://source.android.com/docs/security/test/memory-safety" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Android</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://www.chromium.org/Home/chromium-security/memory-safety/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Chrome</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and many other code bases.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust provides a memory-safe alternative to C and C++ with comparable performance and code size. Additionally it supports interoperability with C with no overhead. The Android team has discussed </span><a href="https://security.googleblog.com/2023/10/bare-metal-rust-in-android.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust for bare-metal firmware previously</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and has </span><a href="https://google.github.io/comprehensive-rust/bare-metal.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">developed training specifically for this domain</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 12pt; margin-top: 12pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Incremental Rust Adoption</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Our incremental approach focusing on replacing new and highest risk existing code (for example, code which processes external untrusted input) can provide maximum security benefits with the least amount of effort. Simply writing any new code in Rust reduces the number of new vulnerabilities and over time can lead to a reduction in </span><a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">the number of outstanding vulnerabilities</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">You can replace existing C functionality by writing a thin Rust shim that translates between an existing Rust API and the C API the codebase expects. The C API is replicated and exported by the shim for the existing codebase to link against. The shim serves as </span><a href="https://doc.rust-lang.org/nomicon/ffi.html#calling-rust-code-from-c" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">a wrapper</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> around the Rust library API, bridging the existing C API and the Rust API. This is a common approach when rewriting or replacing existing libraries with a Rust alternative.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Challenges and Considerations</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">There are several challenges you need to consider before introducing Rust to your firmware codebase. In the following section we address the general state of </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> Rust (that is, bare-metal Rust code), how to find the right off-the-shelf crate (a rust library), porting an std crate to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, using Bindgen to produce FFI bindings, how to approach allocators and panics, and how to set up your toolchain.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">The Rust Standard Library and Bare-Metal Environments</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust's standard library consists of three crates: </span><a href="https://doc.rust-lang.org/core/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">core</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://doc.rust-lang.org/alloc/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">alloc</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and </span><a href="https://doc.rust-lang.org/std/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">std</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate is always available. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate requires an allocator for its functionality. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate assumes a full-blown operating system and is commonly not supported in bare-metal environments. A third-party crate indicates it doesn’t rely on </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> through the crate-level </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std] </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">attribute. This crate is said to be </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible. The rest of the blog will focus on these.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Choosing a Component to Replace</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">When choosing a component to replace, focus on self-contained components with robust testing. Ideally, the components functionality can be provided by an open-source implementation readily available which supports bare-metal environments.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Parsers which handle standard and commonly used data formats or protocols (such as, XML or DNS) are good initial candidates. This ensures the initial effort focuses on the challenges of integrating Rust with the existing code base and build system rather than the particulars of a complex component and simplifies testing. This approach eases introducing more Rust later on.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Choosing a Pre-Existing Crate (Rust Library)</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Picking the right open-source crate (Rust library) to replace the chosen component is crucial. Things to consider are:</span></p><ul style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Is the crate well maintained, for example, are open issues being addressed and does it use recent crate versions?</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">How widely used is the crate? This may be used as a quality signal, but also important to consider in the context of using crates later on which may depend on it.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Does the crate have acceptable documentation?</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Does it have acceptable test coverage?</span></p></li></ul><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Additionally, the crate should ideally be </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible, meaning the standard library is either unused or can be disabled. While a wide range of </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible crates exist, others do not yet support this mode of operation – in those cases, see the next section on converting a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> library to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">By convention, crates which optionally support </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> will provide an </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> feature to indicate whether the standard library should be used. Similarly, the </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> feature usually indicates using an allocator is optional.</span></p><br /><div align="left" dir="ltr" style="margin-left: -14.25pt;"><table style="border-collapse: collapse; border: none;"><colgroup><col width="67"></col><col width="790"></col></colgroup><tbody><tr style="height: 54.75pt;"><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Roboto, sans-serif; font-size: 12pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><span style="border: none; display: inline-block; height: 40px; overflow: hidden; width: 40px;"><img height="40" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfPgBmsZj6ZTOto6Frw_NToC18UKVimJ8SHuCerE7W01D83L3qeJ-Qop83lTf1pvDshgc4CW3pap9aXpzVpSQZtG9EVZDzIQKD5x3vZ4yiEGDxMODTUTNZtlGMVy3Sh-I1i4x-QY8RzBAaqOSap6rGuC9WYg4pdhUO5vY_-OqUCcPssnZAYmUKb-FnV5Ainemg?key=NlrS0k5AvJIpHEA9_mIwTQ" style="margin-left: 0px; margin-top: 0px;" width="40" /></span></span></p></td><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: middle;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 700; vertical-align: baseline; white-space-collapse: preserve;">Note:</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> Even when a library declares </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std] </span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">in its source, there is no guarantee that its dependencies don’t depend on </span><span style="background-color: transparent; color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. We recommend looking through the dependency tree to ensure that all dependencies support </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, or test whether the library compiles for a </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target. The only way to know is currently by trying to compile the crate for a bare-metal target.</span></p></td></tr></tbody></table></div><br /><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For example, one approach is to run </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">cargo check</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> with a bare-metal toolchain provided through </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustup</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustup target add aarch64-unknown-none</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ cargo check</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--target</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">aarch64-unknown-none --no-default-features</span></p><br /><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 14pt;"><span style="font-family: "Google Sans", sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Porting a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: "Google Sans", sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;"> Library to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">no_std</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If a library does not support </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, it might still be possible to port it to a bare-metal environment – especially file format parsers and other OS agnostic workloads. Higher-level functionality such as file handling, threading, and async code may present more of a challenge. In those cases, such functionality can be hidden behind feature flags to still provide the core functionality in a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> build.</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To port a </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate to </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">+</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">):</span></p><ul style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">In the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">cargo.toml</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> file, add a </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> feature, then add this </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> feature to the </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">default </span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">features</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Add the following lines to the top of the </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">lib.rs</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">:</span></p></li></ul><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std]</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#[cfg(feature = "std")]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate std</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">;</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate alloc</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">;</span></p></td></tr></tbody></table></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Then, iteratively fix all occurring compiler errors as follows:</span></p><ol style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Move any </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">use</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> directives from </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> to either </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> or </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">.</span></p></li><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Add </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">use</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> directives for all types that would otherwise automatically be imported by the </span><a href="https://doc.rust-lang.org/std/prelude/index.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; text-wrap: wrap; vertical-align: baseline;">std prelude</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">, such as </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc::vec::Vec</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> and</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> alloc::string::String</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">.</span></p></li><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Hide anything that doesn't exist in </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> or </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> and cannot otherwise be supported in the </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> build (such as file system accesses) behind a </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">#[cfg(feature = </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">"</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">"</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">)] </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">guard.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Anything that needs to interact with the embedded environment may need to be explicitly handled, such as functions for I/O. These likely need to be behind a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">#[cfg(not(feature = "std"))]</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> guard.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Disable </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> for all dependencies (that is, change their definitions in </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Cargo.toml</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">, if using Cargo).</span></p></li></ol><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This needs to be repeated for all dependencies within the crate dependency tree that do not support </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> yet.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Custom Target Architectures</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">There are a number of officially </span><a href="https://doc.rust-lang.org/rustc/platform-support.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">supported targets</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> by the Rust compiler, however, many bare-metal targets are missing from that list. Thankfully, the Rust compiler lowers to LLVM IR and uses an internal copy of LLVM to lower to machine code. Thus, it can support any target architecture that LLVM supports by defining a custom target.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Defining a custom target requires a toolchain built with the </span><a href="https://github.com/rust-lang/rust/blob/master/config.example.toml#L577-L580" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">channel set to dev or nightly</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Rust’s </span><a href="https://docs.rust-embedded.org/embedonomicon/custom-target.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Embedonomicon</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> has a wealth of information on this subject and should be referred to as the source of truth. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To give a quick overview, a custom target JSON file can be constructed by finding a similar supported target and dumping the JSON representation:</span></p><br /><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">list</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z unstable</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">options </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">spec</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p></td></tr></tbody></table></div><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This will print out a target JSON that looks something like:</span></p><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">spec</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z unstable</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">options </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"abi"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"eabi"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"arch"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"arm"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"c-enum-min-bits"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #c53929; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">8</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"crt-objects-fallback"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"false"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"data-layout"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p></td></tr></tbody></table></div><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This output can provide a starting point for defining your target. Of particular note, the data-layout field is defined in the </span><a href="https://llvm.org/docs/LangRef.html#data-layout" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">LLVM documentation</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Once the target is defined, </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">libcore</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">liballoc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (and </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">libstd</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, if applicable) must be built from source for the newly defined target. If using Cargo, building with </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-Z build-std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> accomplishes this, indicating that these libraries should be built from source for your target along with your crate module:</span></p><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"># set build-std to the list of libraries needed</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">cargo build </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z build</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target my_target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json</span></p></td></tr></tbody></table></div><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Building Rust With LLVM Prebuilts</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If the bare-metal architecture is not supported by the LLVM bundled internal to the Rust toolchain, a custom Rust toolchain can be produced with any LLVM prebuilts that support the target.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The instructions for building a Rust toolchain can be found in detail in the </span><a href="https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust Compiler Developer Guide</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. In the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">config.toml</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://github.com/rust-lang/rust/blob/036b38ced36b0ed16579f95b4647ba7424f6b1bc/config.example.toml#L790-L793" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">llvm-config</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> must be set to the path of the LLVM prebuilts.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">You can find the latest Rust Toolchain supported by a particular version of LLVM by checking the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">release notes</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and looking for releases which bump up the minimum supported LLVM version. For example, Rust </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.76</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> bumped the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">minimum LLVM to 16</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.73</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> bumped the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">minimum LLVM to 15</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. That means with LLVM15 prebuilts, the latest Rust toolchain that can be built is </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.75</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Creating a Drop-In Rust Shim</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To create a drop-in replacement for the C/C++ function or API being replaced, the shim needs two things: it must provide the same API as the replaced library and it must know how to run in the firmware’s bare-metal environment.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Exposing the Same API</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The first is achieved by defining a Rust FFI interface with the same function signatures.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">We try to keep the amount of unsafe Rust as minimal as possible by putting the actual implementation in a safe function and exposing a thin wrapper type around.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For example, the FreeRTOS </span><a href="https://github.com/FreeRTOS/coreJSON?tab=readme-ov-file#reference-example" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">coreJSON example</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> includes a </span><a href="https://github.com/FreeRTOS/coreJSON/blob/9ebaeb55cce39a6f79da9cceaa0cbc664a462c8b/source/include/core_json.h#L101-L102" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> C function with the following signature:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate(</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">const</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #9334e6; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">char</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">*</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">buf,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">size_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">max</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">);</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">We can write a shim in Rust between it and the memory safe </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">serde_json</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate to expose the C function signature. We try to keep the unsafe code to a minimum and call through to a safe function early:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#[no_mangle]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">pub</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">unsafe</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"C"</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">fn</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate(buf:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">*const</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">c_char,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">usize)</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-></span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">buf.is_null()</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONNullParameter</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">==</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #c5221f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">0</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONBadParameter</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json_validate(slice_from_raw_parts(buf</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len).as_ref().unwrap())</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #b80672; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">// No more unsafe code in here.</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">fn</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json_validate(buf:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">&[u8])</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-></span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">serde_json::from_slice::<Value>(buf).is_ok()</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONSuccess</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">ILLEGAL_DOC</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><br /><br /><div align="left" dir="ltr" style="margin-left: -16.5pt;"><table style="border-collapse: collapse; border: none;"><colgroup><col width="70"></col><col width="905"></col></colgroup><tbody><tr style="height: 54.75pt;"><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Roboto, sans-serif; font-size: 12pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><span style="border: none; display: inline-block; height: 24px; overflow: hidden; width: 24px;"><img height="24" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfPgBmsZj6ZTOto6Frw_NToC18UKVimJ8SHuCerE7W01D83L3qeJ-Qop83lTf1pvDshgc4CW3pap9aXpzVpSQZtG9EVZDzIQKD5x3vZ4yiEGDxMODTUTNZtlGMVy3Sh-I1i4x-QY8RzBAaqOSap6rGuC9WYg4pdhUO5vY_-OqUCcPssnZAYmUKb-FnV5Ainemg?key=NlrS0k5AvJIpHEA9_mIwTQ" style="margin-left: 0px; margin-top: 0px;" width="24" /></span></span></p></td><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: middle;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 700; vertical-align: baseline; white-space-collapse: preserve;">Note:</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> This is a very simple example. For a highly resource constrained target, you can avoid </span><span style="background-color: transparent; color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and use </span><a href="https://docs.rs/serde-json-core/latest/serde_json_core" style="text-decoration-line: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">serde_json_core</span></a><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, which has even lower overhead but requires pre-defining the JSON structure so it can be allocated on the stack.</span></p></td></tr></tbody></table></div><br /><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For further details on how to create an FFI interface, </span><a href="https://doc.rust-lang.org/nomicon/ffi.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">the Rustinomicon covers this topic extensively</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Calling Back to C/C++ Code</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In order for any Rust component to be functional within a C-based firmware, it will need to call back into the C code for things such as allocations or logging. Thankfully, there are a variety of tools available which automatically generate Rust FFI bindings to C. That way, C functions can easily be invoked from Rust.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The standard means of doing this is with the </span><a href="https://github.com/rust-lang/rust-bindgen" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Bindgen</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> tool. You can use Bindgen to parse all relevant C headers that define the functions Rust needs to call into. It's important to invoke Bindgen with the same </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">CFLAGS</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> as the code in question is built with, to ensure that the bindings are generated correctly.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Experimental support for producing </span><a href="https://github.com/rust-lang/rust-bindgen/discussions/2405" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">bindings to static inline functions</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> is also available.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Hooking Up The Firmware’s Bare-Metal Environment</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Next we need to hook up Rust panic handlers, global allocators, and critical section handlers to the existing code base. This requires producing definitions for each of these which call into the existing firmware C functions.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The Rust panic handler must be defined to handle unexpected states or failed assertions. A custom panic handler can be defined via the </span><a href="https://doc.rust-lang.org/nomicon/panic-handler.html" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">panic_handler</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> attribute</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. This is specific to the target and should, in most cases, either point to an abort function for the current task/process, or a panic function provided by the environment.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If an allocator is available in the firmware and the crate relies on the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate, the Rust allocator can be hooked up by </span><a href="https://doc.rust-lang.org/stable/core/alloc/trait.GlobalAlloc.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">defining a global allocator implementing GlobalAlloc</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If the crate in question relies on concurrency, critical sections will need to be handled. Rust's </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crates do not directly provide a means for defining this, however the </span><a href="https://docs.rs/critical-section/latest/critical_section/" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">critical_section</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> crate</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> is commonly used to handle this functionality for a number of architectures, and can be extended to support more.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">It can be useful to hook up functions for logging as well. Simple wrappers around the firmware’s existing logging functions can expose these to Rust and be used in place of </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eprint </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">and the like. A convenient option is to </span><a href="https://google.github.io/comprehensive-rust/bare-metal/aps/logging.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">implement the </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Log</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> trait</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Fallible Allocations and </span><span style="color: #0f9d58; font-family: "Roboto Mono", monospace; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">alloc</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rusts </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate normally assumes that allocations are infallible (that is, memory allocations won’t fail). However due to memory constraints this isn’t true in most bare-metal environments. Under normal circumstances </span><a href="https://doc.rust-lang.org/stable/std/alloc/fn.handle_alloc_error.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust panics and/or aborts</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> when an allocation fails; this may be acceptable behavior for some bare-metal environments, in which case there are no further considerations when using </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If there’s a clear justification or requirement for fallible allocations however, additional effort is required to ensure that either allocations can’t fail or that failures are handled. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">One approach is to use a crate that provides statically allocated fallible collections, such as the </span><a href="https://docs.rs/heapless/latest/heapless/index.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">heapless</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate, or dynamic fallible allocations like </span><a href="https://docs.rs/fallible_vec/latest/fallible_vec/" style="text-decoration-line: none;"><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">fallible_vec</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Another is to exclusively use </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">try_*</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> methods such as </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Vec::try_reserve</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, which check if the allocation is possible.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust is in the process of formalizing better support for fallible allocations, with an </span><a href="https://doc.rust-lang.org/std/alloc/trait.Allocator.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">experimental allocator in nightly</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> allowing </span><a href="https://doc.rust-lang.org/std/alloc/struct.AllocError.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">failed allocations</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> to be handled by the implementation. There is also the unstable cfg flag for </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> called </span><a href="https://github.com/rust-lang/rust/pull/84266" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">no_global_oom_handling</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> which removes the infallible methods, ensuring they are not used.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Build Optimizations</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Building the Rust library with LTO is necessary to optimize for code size. The existing C/C++ code base does not need to be built with LTO when passing </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-C lto=true</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Additionally, setting </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-C codegen-unit=1</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> results in further optimizations in addition to reproducibility. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If using Cargo to build, the following Cargo.toml settings are recommended to reduce the output library size:</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[profile.release]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">panic</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"abort"</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">lto</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">true</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">codegen-units</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">strip = "symbols"</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"># opt-level "z" may produce better results in some circumstances</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">opt-level</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"s" </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Passing the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-Z remap-cwd-prefix=.</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> flag to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or to Cargo via the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">RUSTFLAGS</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> env var when building with Cargo to strip cwd path strings.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In terms of performance, Rust demonstrates similar performance to C. The most relevant example may be the Rust binder Linux kernel driver, which found “</span><a href="https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com/#:~:text=We%27ve%20found%20that%20Rust%20binder%20has%20similar%20performance%20to%20C%20binder%20on%20the%0AbinderThroughputTest%20benchmark.%20The%20average%20latencies%20fluctuate%20between%0A%2D1.96%25%20and%20%2B1.38%25." style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">that Rust binder has similar performance to C binder</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">”.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">When linking LTO’d Rust staticlibs together with C/C++, it’s recommended to ensure a single Rust staticlib ends up in the final linkage, otherwise there may be </span><a href="https://github.com/rust-lang/rust/issues/44322" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">duplicate symbol errors</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> when linking. This may mean combining multiple Rust shims into a single static library by re-exporting them from a wrapper module.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 12pt; margin-top: 12pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Memory Safety for Firmware, Today</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Using the process outlined in this blog post, You can begin to introduce Rust into large legacy firmware code bases immediately. Replacing security critical components with off-the-shelf open-source memory-safe implementations and developing new features in a memory safe language will lead to fewer critical vulnerabilities while also providing an </span><a href="https://opensource.googleblog.com/2023/06/rust-fact-vs-fiction-5-insights-from-googles-rust-journey-2022.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">improved developer experience</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Roboto, sans-serif; font-size: 12pt; font-style: italic; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Special thanks to our colleagues who have supported and contributed to these efforts: Roger Piqueras Jover, Stephan Chen, Gil Cukierman, Andrew Walbran, and Erik Gilling </span></p><div><span style="font-family: Roboto, sans-serif; font-size: 12pt; font-style: italic; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><br /></span></div></span></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta content='https://plus.google.com/116899029375914044550' itemprop='url'/> </span> </script> <noscript> <p style="text-align: left;"><span class="byline-author">Posted by Ivan Lozano and Dominik Maier, Android Team</span> <p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Android's use of safe-by-design principles drives our adoption of memory-safe languages like Rust, making exploitation of the OS increasingly difficult with every release. To provide a secure foundation, we’re extending hardening and the use of </span><a href="https://security.googleblog.com/2023/10/bare-metal-rust-in-android.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">memory-safe languages to low-level firmware</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (including in </span><a href="https://cs.android.com/android/platform/superproject/main/+/main:trusty/user/app/keymint/lib.rs;drc=4176f2465d7dc81c398730cb579c0a4949a9a832" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Trusty apps</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">).</span></p><br /><p dir="ltr" style="line-height: 1.3800000000000001; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In this blog post, we'll show you how to gradually introduce </span><a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html#:~:text=But%20what%20about%20all%20that%20existing%20C%2B%2B%3F" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust into your existing firmware</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, prioritizing new code and the most security-critical code. You'll see how easy it is to boost security with drop-in Rust replacements, and we'll even demonstrate how the Rust toolchain can handle specialized bare-metal targets.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Drop-in Rust replacements for C code are not a novel idea and have been used in other cases, such as </span><a href="https://mail.gnome.org/archives/desktop-devel-list/2017-January/msg00001.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">librsvg’s adoption of Rust</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> which involved </span><a href="https://web.archive.org/web/20170928062853/https://people.gnome.org/~federico/blog/docs/fmq-porting-c-to-rust.pdf" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">replacing C functions with Rust functions</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> in-place. We seek to demonstrate that this approach is viable for firmware, providing a path to memory-safety in an efficient and effective manner.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Memory Safety for Firmware</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Firmware serves as the interface between hardware and higher-level software. Due to the lack of software security mechanisms that are standard in higher-level software, vulnerabilities in firmware code can be dangerously exploited by malicious actors. Modern phones contain many coprocessors responsible for handling various operations, and each of these run their own firmware. Often, firmware consists of large legacy code bases written in memory-unsafe languages such as C or C++. Memory unsafety is the leading cause of vulnerabilities in </span><a href="https://source.android.com/docs/security/test/memory-safety" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Android</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://www.chromium.org/Home/chromium-security/memory-safety/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Chrome</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and many other code bases.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust provides a memory-safe alternative to C and C++ with comparable performance and code size. Additionally it supports interoperability with C with no overhead. The Android team has discussed </span><a href="https://security.googleblog.com/2023/10/bare-metal-rust-in-android.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust for bare-metal firmware previously</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and has </span><a href="https://google.github.io/comprehensive-rust/bare-metal.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">developed training specifically for this domain</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 12pt; margin-top: 12pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Incremental Rust Adoption</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Our incremental approach focusing on replacing new and highest risk existing code (for example, code which processes external untrusted input) can provide maximum security benefits with the least amount of effort. Simply writing any new code in Rust reduces the number of new vulnerabilities and over time can lead to a reduction in </span><a href="https://security.googleblog.com/2021/04/rust-in-android-platform.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">the number of outstanding vulnerabilities</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">You can replace existing C functionality by writing a thin Rust shim that translates between an existing Rust API and the C API the codebase expects. The C API is replicated and exported by the shim for the existing codebase to link against. The shim serves as </span><a href="https://doc.rust-lang.org/nomicon/ffi.html#calling-rust-code-from-c" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">a wrapper</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> around the Rust library API, bridging the existing C API and the Rust API. This is a common approach when rewriting or replacing existing libraries with a Rust alternative.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Challenges and Considerations</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">There are several challenges you need to consider before introducing Rust to your firmware codebase. In the following section we address the general state of </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> Rust (that is, bare-metal Rust code), how to find the right off-the-shelf crate (a rust library), porting an std crate to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, using Bindgen to produce FFI bindings, how to approach allocators and panics, and how to set up your toolchain.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">The Rust Standard Library and Bare-Metal Environments</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust's standard library consists of three crates: </span><a href="https://doc.rust-lang.org/core/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">core</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://doc.rust-lang.org/alloc/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">alloc</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, and </span><a href="https://doc.rust-lang.org/std/" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">std</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate is always available. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate requires an allocator for its functionality. The </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate assumes a full-blown operating system and is commonly not supported in bare-metal environments. A third-party crate indicates it doesn’t rely on </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> through the crate-level </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std] </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">attribute. This crate is said to be </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible. The rest of the blog will focus on these.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Choosing a Component to Replace</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">When choosing a component to replace, focus on self-contained components with robust testing. Ideally, the components functionality can be provided by an open-source implementation readily available which supports bare-metal environments.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Parsers which handle standard and commonly used data formats or protocols (such as, XML or DNS) are good initial candidates. This ensures the initial effort focuses on the challenges of integrating Rust with the existing code base and build system rather than the particulars of a complex component and simplifies testing. This approach eases introducing more Rust later on.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Choosing a Pre-Existing Crate (Rust Library)</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Picking the right open-source crate (Rust library) to replace the chosen component is crucial. Things to consider are:</span></p><ul style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Is the crate well maintained, for example, are open issues being addressed and does it use recent crate versions?</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">How widely used is the crate? This may be used as a quality signal, but also important to consider in the context of using crates later on which may depend on it.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Does the crate have acceptable documentation?</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Does it have acceptable test coverage?</span></p></li></ul><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Additionally, the crate should ideally be </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible, meaning the standard library is either unused or can be disabled. While a wide range of </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> compatible crates exist, others do not yet support this mode of operation – in those cases, see the next section on converting a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> library to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">By convention, crates which optionally support </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> will provide an </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> feature to indicate whether the standard library should be used. Similarly, the </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> feature usually indicates using an allocator is optional.</span></p><br /><div align="left" dir="ltr" style="margin-left: -14.25pt;"><table style="border-collapse: collapse; border: none;"><colgroup><col width="67"></col><col width="790"></col></colgroup><tbody><tr style="height: 54.75pt;"><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Roboto, sans-serif; font-size: 12pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><span style="border: none; display: inline-block; height: 40px; overflow: hidden; width: 40px;"><img height="40" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfPgBmsZj6ZTOto6Frw_NToC18UKVimJ8SHuCerE7W01D83L3qeJ-Qop83lTf1pvDshgc4CW3pap9aXpzVpSQZtG9EVZDzIQKD5x3vZ4yiEGDxMODTUTNZtlGMVy3Sh-I1i4x-QY8RzBAaqOSap6rGuC9WYg4pdhUO5vY_-OqUCcPssnZAYmUKb-FnV5Ainemg?key=NlrS0k5AvJIpHEA9_mIwTQ" style="margin-left: 0px; margin-top: 0px;" width="40" /></span></span></p></td><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: middle;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 700; vertical-align: baseline; white-space-collapse: preserve;">Note:</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> Even when a library declares </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std] </span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">in its source, there is no guarantee that its dependencies don’t depend on </span><span style="background-color: transparent; color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. We recommend looking through the dependency tree to ensure that all dependencies support </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, or test whether the library compiles for a </span><span style="background-color: transparent; color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target. The only way to know is currently by trying to compile the crate for a bare-metal target.</span></p></td></tr></tbody></table></div><br /><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For example, one approach is to run </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">cargo check</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> with a bare-metal toolchain provided through </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustup</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustup target add aarch64-unknown-none</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ cargo check</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--target</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">aarch64-unknown-none --no-default-features</span></p><br /><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 14pt;"><span style="font-family: "Google Sans", sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Porting a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: "Google Sans", sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;"> Library to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">no_std</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If a library does not support </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, it might still be possible to port it to a bare-metal environment – especially file format parsers and other OS agnostic workloads. Higher-level functionality such as file handling, threading, and async code may present more of a challenge. In those cases, such functionality can be hidden behind feature flags to still provide the core functionality in a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> build.</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To port a </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate to </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">+</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">):</span></p><ul style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">In the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">cargo.toml</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> file, add a </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> feature, then add this </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> feature to the </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">default </span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">features</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: disc; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Add the following lines to the top of the </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">lib.rs</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">:</span></p></li></ul><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#![no_std]</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#[cfg(feature = "std")]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate std</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">;</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate alloc</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">;</span></p></td></tr></tbody></table></div><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Then, iteratively fix all occurring compiler errors as follows:</span></p><ol style="margin-bottom: 0; margin-top: 0; padding-inline-start: 48px;"><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Move any </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">use</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> directives from </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> to either </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> or </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">.</span></p></li><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Add </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">use</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> directives for all types that would otherwise automatically be imported by the </span><a href="https://doc.rust-lang.org/std/prelude/index.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; text-wrap: wrap; vertical-align: baseline;">std prelude</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">, such as </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc::vec::Vec</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> and</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> alloc::string::String</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">.</span></p></li><li aria-level="1" dir="ltr" style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Hide anything that doesn't exist in </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> or </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> and cannot otherwise be supported in the </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">no_std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> build (such as file system accesses) behind a </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">#[cfg(feature = </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">"</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">"</span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">)] </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">guard.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Anything that needs to interact with the embedded environment may need to be explicitly handled, such as functions for I/O. These likely need to be behind a </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">#[cfg(not(feature = "std"))]</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> guard.</span></p></li><li aria-level="1" dir="ltr" style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; list-style-type: lower-alpha; vertical-align: baseline; white-space: pre;"><p dir="ltr" role="presentation" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Disable </span><span style="color: #0d904f; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">std</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;"> for all dependencies (that is, change their definitions in </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">Cargo.toml</span><span style="font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-wrap: wrap; vertical-align: baseline;">, if using Cargo).</span></p></li></ol><p dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 0pt;"><span style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This needs to be repeated for all dependencies within the crate dependency tree that do not support </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">no_std</span><span style="font-family: "Google Sans", sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> yet.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Custom Target Architectures</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">There are a number of officially </span><a href="https://doc.rust-lang.org/rustc/platform-support.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">supported targets</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> by the Rust compiler, however, many bare-metal targets are missing from that list. Thankfully, the Rust compiler lowers to LLVM IR and uses an internal copy of LLVM to lower to machine code. Thus, it can support any target architecture that LLVM supports by defining a custom target.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Defining a custom target requires a toolchain built with the </span><a href="https://github.com/rust-lang/rust/blob/master/config.example.toml#L577-L580" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">channel set to dev or nightly</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Rust’s </span><a href="https://docs.rust-embedded.org/embedonomicon/custom-target.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Embedonomicon</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> has a wealth of information on this subject and should be referred to as the source of truth. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To give a quick overview, a custom target JSON file can be constructed by finding a similar supported target and dumping the JSON representation:</span></p><br /><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">list</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z unstable</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">options </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">spec</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p></td></tr></tbody></table></div><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This will print out a target JSON that looks something like:</span></p><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">$ rustc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; color: #9c27b0; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">spec</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z unstable</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">options </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">armv7a</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">none</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eabi</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"abi"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"eabi"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"arch"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"arm"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"c-enum-min-bits"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #c53929; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">8</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"crt-objects-fallback"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"false"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"data-layout"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">:</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="background-color: transparent; color: #0f9d58; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">  </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[...]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p></td></tr></tbody></table></div><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">This output can provide a starting point for defining your target. Of particular note, the data-layout field is defined in the </span><a href="https://llvm.org/docs/LangRef.html#data-layout" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">LLVM documentation</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Once the target is defined, </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">libcore</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">liballoc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> (and </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">libstd</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, if applicable) must be built from source for the newly defined target. If using Cargo, building with </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-Z build-std</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> accomplishes this, indicating that these libraries should be built from source for your target along with your crate module:</span></p><div align="left" dir="ltr" style="margin-left: 0pt;"><table style="border-collapse: collapse; border: none;"><colgroup></colgroup><tbody><tr style="height: 0pt;"><td style="background-color: #fafafa; border-bottom: solid #e0e0e0 1pt; border-left: solid #e0e0e0 1pt; border-right: solid #e0e0e0 1pt; border-top: solid #e0e0e0 1pt; overflow-wrap: break-word; overflow: hidden; padding: 5pt 5pt 5pt 5pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #455a64; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"># set build-std to the list of libraries needed</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">cargo build </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Z build</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">std</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">,</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc </span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">--</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">target my_target</span><span style="background-color: transparent; color: #616161; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span><span style="background-color: transparent; font-family: Consolas, sans-serif; font-size: 10pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json</span></p></td></tr></tbody></table></div><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Building Rust With LLVM Prebuilts</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If the bare-metal architecture is not supported by the LLVM bundled internal to the Rust toolchain, a custom Rust toolchain can be produced with any LLVM prebuilts that support the target.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The instructions for building a Rust toolchain can be found in detail in the </span><a href="https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust Compiler Developer Guide</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. In the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">config.toml</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, </span><a href="https://github.com/rust-lang/rust/blob/036b38ced36b0ed16579f95b4647ba7424f6b1bc/config.example.toml#L790-L793" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">llvm-config</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> must be set to the path of the LLVM prebuilts.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">You can find the latest Rust Toolchain supported by a particular version of LLVM by checking the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">release notes</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and looking for releases which bump up the minimum supported LLVM version. For example, Rust </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.76</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> bumped the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">minimum LLVM to 16</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.73</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> bumped the </span><a href="https://github.com/rust-lang/rust/blob/master/RELEASES.md" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">minimum LLVM to 15</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. That means with LLVM15 prebuilts, the latest Rust toolchain that can be built is </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1.75</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 20pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Creating a Drop-In Rust Shim</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">To create a drop-in replacement for the C/C++ function or API being replaced, the shim needs two things: it must provide the same API as the replaced library and it must know how to run in the firmware’s bare-metal environment.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Exposing the Same API</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The first is achieved by defining a Rust FFI interface with the same function signatures.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">We try to keep the amount of unsafe Rust as minimal as possible by putting the actual implementation in a safe function and exposing a thin wrapper type around.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For example, the FreeRTOS </span><a href="https://github.com/FreeRTOS/coreJSON?tab=readme-ov-file#reference-example" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">coreJSON example</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> includes a </span><a href="https://github.com/FreeRTOS/coreJSON/blob/9ebaeb55cce39a6f79da9cceaa0cbc664a462c8b/source/include/core_json.h#L101-L102" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> C function with the following signature:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate(</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">const</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #9334e6; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">char</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">*</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">buf,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">size_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">max</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">);</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">We can write a shim in Rust between it and the memory safe </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">serde_json</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate to expose the C function signature. We try to keep the unsafe code to a minimum and call through to a safe function early:</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">#[no_mangle]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">pub</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">unsafe</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">extern</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"C"</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">fn</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSON_Validate(buf:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">*const</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">c_char,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">usize)</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-></span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus_t</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">buf.is_null()</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONNullParameter</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">==</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #c5221f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">0</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONBadParameter</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json_validate(slice_from_raw_parts(buf</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_,</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">len).as_ref().unwrap())</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">as</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">_</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #b80672; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">// No more unsafe code in here.</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">fn</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">json_validate(buf:</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">&[u8])</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-></span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">if</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">serde_json::from_slice::<Value>(buf).is_ok()</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">JSONStatus::JSONSuccess</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #1967d2; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">else</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">{</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">        </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">ILLEGAL_DOC</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">    </span><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #37474f; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">}</span></p><br /><br /><div align="left" dir="ltr" style="margin-left: -16.5pt;"><table style="border-collapse: collapse; border: none;"><colgroup><col width="70"></col><col width="905"></col></colgroup><tbody><tr style="height: 54.75pt;"><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: top;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Roboto, sans-serif; font-size: 12pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><span style="border: none; display: inline-block; height: 24px; overflow: hidden; width: 24px;"><img height="24" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfPgBmsZj6ZTOto6Frw_NToC18UKVimJ8SHuCerE7W01D83L3qeJ-Qop83lTf1pvDshgc4CW3pap9aXpzVpSQZtG9EVZDzIQKD5x3vZ4yiEGDxMODTUTNZtlGMVy3Sh-I1i4x-QY8RzBAaqOSap6rGuC9WYg4pdhUO5vY_-OqUCcPssnZAYmUKb-FnV5Ainemg?key=NlrS0k5AvJIpHEA9_mIwTQ" style="margin-left: 0px; margin-top: 0px;" width="24" /></span></span></p></td><td style="background-color: #e1f5fe; overflow-wrap: break-word; overflow: hidden; padding: 14.4pt 14.4pt 14.4pt 14.4pt; vertical-align: middle;"><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 700; vertical-align: baseline; white-space-collapse: preserve;">Note:</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> This is a very simple example. For a highly resource constrained target, you can avoid </span><span style="background-color: transparent; color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> and use </span><a href="https://docs.rs/serde-json-core/latest/serde_json_core" style="text-decoration-line: none;"><span style="background-color: transparent; color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">serde_json_core</span></a><span style="background-color: transparent; color: #01579b; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, which has even lower overhead but requires pre-defining the JSON structure so it can be allocated on the stack.</span></p></td></tr></tbody></table></div><br /><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">For further details on how to create an FFI interface, </span><a href="https://doc.rust-lang.org/nomicon/ffi.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">the Rustinomicon covers this topic extensively</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Calling Back to C/C++ Code</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In order for any Rust component to be functional within a C-based firmware, it will need to call back into the C code for things such as allocations or logging. Thankfully, there are a variety of tools available which automatically generate Rust FFI bindings to C. That way, C functions can easily be invoked from Rust.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The standard means of doing this is with the </span><a href="https://github.com/rust-lang/rust-bindgen" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Bindgen</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> tool. You can use Bindgen to parse all relevant C headers that define the functions Rust needs to call into. It's important to invoke Bindgen with the same </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">CFLAGS</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> as the code in question is built with, to ensure that the bindings are generated correctly.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Experimental support for producing </span><a href="https://github.com/rust-lang/rust-bindgen/discussions/2405" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">bindings to static inline functions</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> is also available.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Hooking Up The Firmware’s Bare-Metal Environment</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Next we need to hook up Rust panic handlers, global allocators, and critical section handlers to the existing code base. This requires producing definitions for each of these which call into the existing firmware C functions.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">The Rust panic handler must be defined to handle unexpected states or failed assertions. A custom panic handler can be defined via the </span><a href="https://doc.rust-lang.org/nomicon/panic-handler.html" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">panic_handler</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> attribute</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. This is specific to the target and should, in most cases, either point to an abort function for the current task/process, or a panic function provided by the environment.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If an allocator is available in the firmware and the crate relies on the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate, the Rust allocator can be hooked up by </span><a href="https://doc.rust-lang.org/stable/core/alloc/trait.GlobalAlloc.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">defining a global allocator implementing GlobalAlloc</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If the crate in question relies on concurrency, critical sections will need to be handled. Rust's </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">core</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crates do not directly provide a means for defining this, however the </span><a href="https://docs.rs/critical-section/latest/critical_section/" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">critical_section</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> crate</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> is commonly used to handle this functionality for a number of architectures, and can be extended to support more.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">It can be useful to hook up functions for logging as well. Simple wrappers around the firmware’s existing logging functions can expose these to Rust and be used in place of </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">print</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">eprint </span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">and the like. A convenient option is to </span><a href="https://google.github.io/comprehensive-rust/bare-metal/aps/logging.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">implement the </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Log</span><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;"> trait</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 10pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Fallible Allocations and </span><span style="color: #0f9d58; font-family: "Roboto Mono", monospace; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">alloc</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rusts </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate normally assumes that allocations are infallible (that is, memory allocations won’t fail). However due to memory constraints this isn’t true in most bare-metal environments. Under normal circumstances </span><a href="https://doc.rust-lang.org/stable/std/alloc/fn.handle_alloc_error.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">Rust panics and/or aborts</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> when an allocation fails; this may be acceptable behavior for some bare-metal environments, in which case there are no further considerations when using </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If there’s a clear justification or requirement for fallible allocations however, additional effort is required to ensure that either allocations can’t fail or that failures are handled. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">One approach is to use a crate that provides statically allocated fallible collections, such as the </span><a href="https://docs.rs/heapless/latest/heapless/index.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">heapless</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> crate, or dynamic fallible allocations like </span><a href="https://docs.rs/fallible_vec/latest/fallible_vec/" style="text-decoration-line: none;"><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">fallible_vec</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Another is to exclusively use </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">try_*</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> methods such as </span><span style="color: #0f9d58; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Vec::try_reserve</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">, which check if the allocation is possible.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Rust is in the process of formalizing better support for fallible allocations, with an </span><a href="https://doc.rust-lang.org/std/alloc/trait.Allocator.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">experimental allocator in nightly</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> allowing </span><a href="https://doc.rust-lang.org/std/alloc/struct.AllocError.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">failed allocations</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> to be handled by the implementation. There is also the unstable cfg flag for </span><span style="color: #0d904f; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">alloc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> called </span><a href="https://github.com/rust-lang/rust/pull/84266" style="text-decoration-line: none;"><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">no_global_oom_handling</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> which removes the infallible methods, ensuring they are not used.</span></p><h2 dir="ltr" style="line-height: 1.38; margin-bottom: 6pt; margin-top: 18pt;"><span style="font-family: Arial, sans-serif; font-size: 16pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Build Optimizations</span></h2><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Building the Rust library with LTO is necessary to optimize for code size. The existing C/C++ code base does not need to be built with LTO when passing </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-C lto=true</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">. Additionally, setting </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-C codegen-unit=1</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> results in further optimizations in addition to reproducibility. </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">If using Cargo to build, the following Cargo.toml settings are recommended to reduce the output library size:</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">[profile.release]</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">panic</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"abort"</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">lto</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">true</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">codegen-units</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">1</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">strip = "symbols"</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"># opt-level "z" may produce better results in some circumstances</span></p><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">opt-level</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">=</span><span style="font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> </span><span style="color: #188038; font-family: "Roboto Mono", monospace; font-size: 9pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">"s" </span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Passing the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">-Z remap-cwd-prefix=.</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> flag to </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">rustc</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> or to Cargo via the </span><span style="color: #0d904f; font-family: Consolas, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">RUSTFLAGS</span><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> env var when building with Cargo to strip cwd path strings.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">In terms of performance, Rust demonstrates similar performance to C. The most relevant example may be the Rust binder Linux kernel driver, which found “</span><a href="https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com/#:~:text=We%27ve%20found%20that%20Rust%20binder%20has%20similar%20performance%20to%20C%20binder%20on%20the%0AbinderThroughputTest%20benchmark.%20The%20average%20latencies%20fluctuate%20between%0A%2D1.96%25%20and%20%2B1.38%25." style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">that Rust binder has similar performance to C binder</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">”.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">When linking LTO’d Rust staticlibs together with C/C++, it’s recommended to ensure a single Rust staticlib ends up in the final linkage, otherwise there may be </span><a href="https://github.com/rust-lang/rust/issues/44322" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">duplicate symbol errors</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"> when linking. This may mean combining multiple Rust shims into a single static library by re-exporting them from a wrapper module.</span></p><h1 dir="ltr" style="line-height: 1.38; margin-bottom: 12pt; margin-top: 12pt;"><span style="font-family: Arial, sans-serif; font-size: 20pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; font-weight: 400; vertical-align: baseline; white-space-collapse: preserve;">Memory Safety for Firmware, Today</span></h1><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Using the process outlined in this blog post, You can begin to introduce Rust into large legacy firmware code bases immediately. Replacing security critical components with off-the-shelf open-source memory-safe implementations and developing new features in a memory safe language will lead to fewer critical vulnerabilities while also providing an </span><a href="https://opensource.googleblog.com/2023/06/rust-fact-vs-fiction-5-insights-from-googles-rust-journey-2022.html" style="text-decoration-line: none;"><span style="color: #1155cc; font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; text-decoration-line: underline; text-decoration-skip-ink: none; vertical-align: baseline; white-space-collapse: preserve;">improved developer experience</span></a><span style="font-family: Arial, sans-serif; font-size: 11pt; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">.</span></p><br /><p dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 0pt;"><span style="font-family: Roboto, sans-serif; font-size: 12pt; font-style: italic; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;">Special thanks to our colleagues who have supported and contributed to these efforts: Roger Piqueras Jover, Stephan Chen, Gil Cukierman, Andrew Walbran, and Erik Gilling </span></p><div><span style="font-family: Roboto, sans-serif; font-size: 12pt; font-style: italic; font-variant-alternates: normal; font-variant-east-asian: normal; font-variant-numeric: normal; font-variant-position: normal; vertical-align: baseline; white-space-collapse: preserve;"><br /></span></div></span></div> <span itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'> <meta 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class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2023/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2022/'> 2022 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2022/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2021/'> 2021 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/10/'> Oct </a> </div> <div class='items'> 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<div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2021/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2020/'> 2020 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2020/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2019/'> 2019 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2019/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2018/'> 2018 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2018/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2017/'> 2017 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2017/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2016/'> 2016 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2016/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2015/'> 2015 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2015/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2014/'> 2014 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2014/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2013/'> 2013 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2013/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2012/'> 2012 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2012/01/'> Jan </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2011/'> 2011 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2011/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2010/'> 2010 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/09/'> Sep </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/04/'> Apr </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2010/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2009/'> 2009 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/06/'> Jun </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2009/03/'> Mar </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2008/'> 2008 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/12/'> Dec </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/08/'> Aug </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/07/'> Jul </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/05/'> May </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2008/02/'> Feb </a> </div> <div class='items'> </div> </li> </ul> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class='intervalToggle'> <span class='new-toggle' href='javascript:void(0)'> <i class='material-icons arrow'>  </i> </span> <a class='toggle' href='javascript:void(0)' style='display: none'> <span class='zippy'> <i class='material-icons'>  </i>   </span> </a> <a class='post-count-link' href='https://security.googleblog.com/2007/'> 2007 </a> </div> <div class='items'> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2007/11/'> Nov </a> </div> <div class='items'> </div> </li> </ul> <ul class='hierarchy'> <li class='archivedate collapsed'> <div class=''> <a class='post-count-link' href='https://security.googleblog.com/2007/10/'> Oct </a> </div> <div class='items'> </div> </li> </ul> <ul 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