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 <section id="frequently-asked-questions">
 <h1 id="frequently-asked-questions">Frequently Asked Questions</h1>
 <div class="contents local" id="contents" style="display: none">
 <ul class="small-gap">
 <li><p class="first"><a class="reference internal" href="#what-is-native-client-good-for" id="id1">What is Native Client Good For?</a></p>
 <ul class="small-gap">
 <li><a class="reference internal" href="#why-did-google-build-native-client" id="id2">Why did Google build Native Client?</a></li>
 <li><a class="reference internal" href="#when-should-i-use-portable-native-client-instead-of-native-client" id="id3">When should I use Portable Native Client instead of Native Client?</a></li>
@@ skipping 61 matching lines @@
 
 </div><p>This document answers some frequently asked questions about Native
 Client (NaCl) and Portable Native Client (PNaCl, pronounced
 &#8220;pinnacle&#8221;). For a high-level overview of Native Client, see the
 <a class="reference internal" href="/native-client/overview.html"><em>Technical Overview</em></a>.</p>
 <p>If you have questions that aren&#8217;t covered in this FAQ:</p>
 <ul class="small-gap">
 <li>Scan through the <a class="reference internal" href="/native-client/sdk/release-notes.html"><em>Release Notes</em></a>.</li>
 <li>Search through or ask on the <a class="reference internal" href="/native-client/help.html"><em>Native Client Forums</em></a>.</li>
 </ul>
-<section id="what-is-native-client-good-for">
 <h2 id="what-is-native-client-good-for">What is Native Client Good For?</h2>
-<section id="why-did-google-build-native-client">
 <h3 id="why-did-google-build-native-client">Why did Google build Native Client?</h3>
 <ul class="small-gap">
 <li><strong>Performance:</strong> Native Client modules run nearly as fast as native
 compiled code.</li>
 <li><strong>Security:</strong> Native Client lets users run native compiled code in the
 browser with the same level of security and privacy as traditional web
 applications.</li>
 <li><p class="first"><strong>Convenience:</strong></p>
 <ul class="small-gap">
 <li>Developers can leverage existing code, written in C/C++ or other
@@ skipping 23 matching lines @@
 already-released applications.</li>
 <li><strong>Convenience:</strong> Developers only need to ship a single <code>.pexe</code> file,
 not one <code>.nexe</code> file per supported architecture.</li>
 <li><strong>Portability:</strong> Developers and users don&#8217;t need to worry about
 already-released applications not working on new hardware: PNaCl
 already supports all architectures NaCl does, and as PNaCl evolves it
 gains support for new processors and fully uses their capabilities.</li>
 </ul>
 <p>For more details, refer to the <a class="reference internal" href="/native-client/nacl-and-pnacl.html"><em>history behind and comparison of
 NaCl and PNaCl</em></a>.</p>
-</section><section id="when-should-i-use-portable-native-client-instead-of-native-client">
 <h3 id="when-should-i-use-portable-native-client-instead-of-native-client">When should I use Portable Native Client instead of Native Client?</h3>
 <p>See <a class="reference internal" href="/native-client/nacl-and-pnacl.html"><em>NaCl and PNaCl</em></a>. In short: PNaCl works on the Open
 Web platform delivered by Chrome whereas NaCl only works on the Chrome Web
 Store.</p>
-</section><section id="when-should-i-use-portable-native-client-native-client">
 <h3 id="when-should-i-use-portable-native-client-native-client">When should I use Portable Native Client / Native Client?</h3>
 <p>The following are some typical use cases. For details, see the
 <a class="reference internal" href="/native-client/overview.html"><em>Technical Overview</em></a>.</p>
 <ul class="small-gap">
 <li>Porting existing applications or software components, written in C/C++ or
 virtual machines written in C/C++, for use in a web application.</li>
 <li><p class="first">Using compute-intensive applications, including threads and SIMD, such as:</p>
 <ul class="small-gap">
 <li>Scientific computing.</li>
 <li>Handling multimedia for a web application.</li>
 <li>Various aspects of web-based games, including physics engines and AI.</li>
 </ul>
 </li>
 <li>Running untrusted code on a server or within an application (such as a plugin
 system for a game).</li>
 </ul>
 <p>Portable Native Client and Native Client are versatile technologies which are
 used in many other contexts outside of Chrome.</p>
-</section><section id="how-fast-does-code-run-in-portable-native-client">
 <h3 id="how-fast-does-code-run-in-portable-native-client">How fast does code run in Portable Native Client?</h3>
 <p>Fast! The SPEC2k benchmarks (C, C++ and floating-point benchmarks) give
 the following overhead for optimized PNaCl compared to regular optimized
 LLVM:</p>
 <table border="1" class="docutils">
 <colgroup>
 </colgroup>
 <tbody valign="top">
 <tr class="row-odd"><td>x86-32</td>
 <td>15%</td>
@@ skipping 14 matching lines @@
 native code such as <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#language-support-threading"><em>threading</em></a> and
 <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#portable-simd-vectors"><em>Portable SIMD Vectors</em></a>.</p>
 <p>For details, see:</p>
 <ul class="small-gap">
 <li><a class="reference external" href="https://www.youtube.com/watch?v=675znN6tntw&amp;list=PLOU2XLYxmsIIwGK7v7jg3gQvIAWJzdat_">PNaCl SIMD: Speed on the Web</a>.</li>
 <li><a class="reference external" href="https://nativeclient.googlecode.com/svn/data/site/NaCl_SFI.pdf">Adapting Software Fault Isolation to Contemporary CPU Architectures</a> (PDF).</li>
 <li><a class="reference external" href="http://research.google.com/pubs/pub34913.html">Native Client: A Sandbox for Portable, Untrusted x86 Code</a> (PDF).</li>
 </ul>
 <p>If your code isn&#8217;t performing as close to native speed as you&#8217;d expect,
 <a class="reference internal" href="/native-client/help.html"><em>let us know</em></a>!</p>
-</section><section id="why-use-portable-native-client-instead-of-technology-x">
 <h3 id="why-use-portable-native-client-instead-of-technology-x">Why use Portable Native Client instead of <em>&lt;technology X&gt;</em>?</h3>
 <p>Many other technologies can be compared to Portable Native Client:
 Flash, Java, Silverlight, ActiveX, .NET, asm.js, etc...</p>
 <p>Different technologies have different strengths and weaknesses. In
 appropriate contexts, Portable Native Client can be faster, more secure,
 and/or more compatible across operating systems and architectures than
 other technologies.</p>
 <p>Portable Native Client complement other technologies by giving web
 developers a new capability: the ability to run fast, secure native code
 from a web browser in an architecture-independent way.</p>
-</section><section id="if-i-want-direct-access-to-the-os-should-i-use-native-client">
 <h3 id="if-i-want-direct-access-to-the-os-should-i-use-native-client">If I want direct access to the OS, should I use Native Client?</h3>
 <p>No&#8212;Native Client does not provide direct access to the OS or devices,
 or otherwise bypass the JavaScript security model. For more information,
 see later sections of this FAQ.</p>
-</section></section><section id="development-environments-and-tools">
 <h2 id="development-environments-and-tools">Development Environments and Tools</h2>
-<section id="what-development-environment-and-development-operating-system-do-you-recommend">
 <h3 id="what-development-environment-and-development-operating-system-do-you-recommend">What development environment and development operating system do you recommend?</h3>
 <p>You can develop on Windows, Mac, or Linux, and the resulting Native Client or
 Portable Native Client application will run inside the Google Chrome browser on
 all those platforms as well as ChromeOS. You can also develop on ChromeOS with
 <a class="reference external" href="https://github.com/dnschneid/crouton">Crouton</a> or our <a class="reference external" href="https://www.youtube.com/watch?v=OzNuzBDEWzk&amp;list=PLOU2XLYxmsIIwGK7v7jg3gQvIAWJzdat_">experimental development environment which runs within NaCl</a>,
 and we&#8217;re working on self-hosting a full development environment on Portable
 Native Client.</p>
 <p>Any editor+shell combination should work as well as IDEs like Eclipse,
 Visual Studio with the <a class="reference internal" href="/native-client/devguide/devcycle/vs-addin.html"><em>Native Client Add-In</em></a> on Windows, or Xcode on Mac OSX.</p>
-</section><section id="i-m-not-familiar-with-native-development-tools-can-i-still-use-the-native-client-sdk">
 <h3 id="i-m-not-familiar-with-native-development-tools-can-i-still-use-the-native-client-sdk">I&#8217;m not familiar with native development tools, can I still use the Native Client SDK?</h3>
 <p>You may find our <a class="reference internal" href="/native-client/devguide/tutorial/index.html"><em>Tutorial</em></a> and <a class="reference internal" href="/native-client/devguide/devcycle/building.html"><em>Building
 instructions</em></a> useful, and you can look at
 the code and Makefiles for the SDK examples to understand how the
 examples are built and run.</p>
 <p>You&#8217;ll need to learn how to use some tools (like GCC, LLVM, make, Eclipse,
 Visual Studio, or Xcode) before you can get very far with the SDK. Try seaching
 for an <a class="reference external" href="https://www.google.com/search?q=gcc+introduction">introduction to GCC</a>.</p>
-</section></section><section id="openness-and-supported-architectures-and-languages">
 <h2 id="openness-and-supported-architectures-and-languages">Openness, and Supported Architectures and Languages</h2>
-<section id="is-native-client-open-is-it-a-standard">
 <h3 id="is-native-client-open-is-it-a-standard">Is Native Client open? Is it a standard?</h3>
 <p>Native Client is completely open: the executable format is open and the
 <a class="reference external" href="https://code.google.com/p/nativeclient/">source code is open</a>. Right
 now the Native Client project is in its early stages, so it&#8217;s premature
 to consider Native Client for standardization.</p>
 <p>We consistenly try to document our design and implementation and hope to
 standardize Portable Native Client when it gains more traction. A good
 example is our <a class="reference internal" href="/native-client/reference/pnacl-bitcode-abi.html"><em>PNaCl bitcode reference manual</em></a>.</p>
-</section><section id="what-are-the-supported-instruction-set-architectures">
 <h3 id="what-are-the-supported-instruction-set-architectures">What are the supported instruction set architectures?</h3>
 <p>Portable Native Client uses an architecture-independent format (the
 <code>.pexe</code>) which can currently be translated to execute on processors
 with the x86-32, x86-64, and ARM instruction set architectures, as well
 as experimental support for MIPS. As new architectures come along and
 become popular we expect Portable Native Client to support them without
 developers having to recompile their code.</p>
 <p>Native Client can currently execute on the same architectures as
 Portable Native Client but is only supported on the Chrome Web
 Store. Native Client&#8217;s <code>.nexe</code> files are architecture-dependent and
 cannot adapt to new architectures without recompilation, we therefore
 deem them better suited to a web store than to the open web.</p>
 <p>With Portable Native Client we deliver a system that has comparable
 portability to JavaScript and can adapt to new instruction set
 architectures without requiring recompilation. The web is better when
 it&#8217;s platform-independent, and we&#8217;d like it to stay that way.</p>
-</section><section id="do-i-have-to-use-c-or-c-i-d-really-like-to-use-another-language">
-<span id="other-languages"></span><h3 id="do-i-have-to-use-c-or-c-i-d-really-like-to-use-another-language"><span id="other-languages"></span>Do I have to use C or C++? I&#8217;d really like to use another language.</h3>
+<h3 id="do-i-have-to-use-c-or-c-i-d-really-like-to-use-another-language"><span id="other-languages"></span>Do I have to use C or C++? I&#8217;d really like to use another language.</h3>
 <p>Right now only C and C++ are supported directly by the toolchain in the SDK. C#
 and other languages in the .NET family are supported via the <a class="reference external" href="https://github.com/elijahtaylor/mono">Mono port</a> for
 Native Client. Moreover, there are several ongoing projects to support
 additional language runtimes (e.g. <a class="reference external" href="https://code.google.com/p/naclports/source/browse#svn%2Ftrunk%2Fsrc%2Fexamples%2Ftools">naclports supports Lua, Python and Ruby</a>)
 as well as to compile more languages to LLVM&#8217;s intermediate representation
 (e.g. support <a class="reference external" href="http://halide-lang.org/">Halide</a>, Haskell with <a class="reference external" href="http://www.haskell.org/ghc/docs/latest/html/users_guide/code-generators.html">GHC</a> or support Fortran with <a class="reference external" href="https://flang-gsoc.blogspot.ie/2013/09/end-of-gsoc-report.html">flang</a>), or
 transpile languages to C/C++ (source-to-source compilation).</p>
 <p>If you&#8217;re interested in getting other languages working, please contact the
 Native Client team by way of the <a class="reference external" href="https://groups.google.com/group/native-client-discuss">native-client-discuss</a> mailing list.</p>
-</section><section id="do-you-only-support-chrome-what-about-other-browsers">
 <h3 id="do-you-only-support-chrome-what-about-other-browsers">Do you only support Chrome? What about other browsers?</h3>
 <p>We aim to support multiple browsers. However, a number of features that
 we consider requirements for a production-quality system that keeps the
 user safe are difficult to implement without help from the
 browser. Specific examples are an out-of-process plugin architecture and
 appropriate interfaces for integrated 3D graphics. We have worked
 closely with Chromium developers to deliver these features and we are
 eager to collaborate with developers from other browsers.</p>
-</section><section id="what-s-the-difference-between-npapi-and-pepper">
 <h3 id="what-s-the-difference-between-npapi-and-pepper">What&#8217;s the difference between NPAPI and Pepper?</h3>
 <p><a class="reference internal" href="/native-client/pepper_stable/index.html"><em>Pepper</em></a> (also known as PPAPI) is a new API that
 lets Native Client modules communicate with the browser. Pepper supports
 various features that don&#8217;t have robust support in NPAPI, such as event
 handling, out-of-process plugins, and asynchronous interfaces. Native
 Client has transitioned from using NPAPI to using Pepper.</p>
-</section><section id="is-npapi-part-of-the-native-client-sdk">
 <h3 id="is-npapi-part-of-the-native-client-sdk">Is NPAPI part of the Native Client SDK?</h3>
 <p>NPAPI is not supported by the Native Client SDK, and is <a class="reference external" href="http://blog.chromium.org/2013/09/saying-goodbye-to-our-old-friend-npapi.html">deprecated in Chrome</a>.</p>
-</section><section id="does-native-client-support-simd-vector-instructions">
 <h3 id="does-native-client-support-simd-vector-instructions">Does Native Client support SIMD vector instructions?</h3>
 <p>Native Client currently supports SSE on x86 and NEON on ARM. Support for
 AVX on x86 is under way.</p>
 <p>Portable Native Client supports portable SIMD vectors, as detailed in
 <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#portable-simd-vectors"><em>Portable SIMD Vectors</em></a>.</p>
-</section><section id="can-i-use-native-client-for-3d-graphics">
 <h3 id="can-i-use-native-client-for-3d-graphics">Can I use Native Client for 3D graphics?</h3>
 <p>Yes. Native Client supports <a class="reference external" href="https://www.khronos.org/opengles/">OpenGL ES 2.0</a>.</p>
 <p>To alert the user regarding their hardware platform&#8217;s 3D feature set
 before loading a large NaCl application, see <a class="reference internal" href="/native-client/devguide/coding/3D-graphics.html"><em>Vetting the driver in
 Javascript</em></a>.</p>
 <p>Some GL extensions are exposed to Native Client applications, see the <a class="reference external" href="https://code.google.com/p/chromium/codesearch#chromium/src/ppapi/lib/gl/gles2/gles2.c">GLES2
 file</a>.  This file is part of the GL wrapper supplied by the library
 <code>ppapi_gles2</code> which you&#8217;ll want to include in your project.  In most cases
 extensions map to extensions available on other platforms, or differ very
 slightly (if they differ, the extension is usually CHROMIUM or ANGLE instead of
 EXT).</p>
-</section><section id="does-native-client-support-concurrency-parallelism">
 <h3 id="does-native-client-support-concurrency-parallelism">Does Native Client support concurrency/parallelism?</h3>
 <p>Native Client and Portable Native Client both support pthreads,
 C11/C++11 threads, and low-level synchronization primitives (mutex,
 barriers, atomic read/modify/write, compare-and-exchange, etc...), thus
 allowing your Native Client application to utilize several CPU cores.
 Note that this allows you to modify datastructures concurrently without
 needing to copy them, which is often a limitation of shared-nothing
 systems. For more information see <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#memory-model-and-atomics"><em>memory model and atomics</em></a> and <a class="reference internal" href="/native-client/reference/pnacl-c-cpp-language-support.html#language-support-threading"><em>threading</em></a>.</p>
 <p>Native Client doesn&#8217;t support HTML5 Web Workers directly but can
 interact with JavaScript code which does.</p>
-</section></section><section id="coming-soon">
 <h2 id="coming-soon">Coming Soon</h2>
-<section id="do-native-client-modules-have-access-to-external-devices">
 <h3 id="do-native-client-modules-have-access-to-external-devices">Do Native Client modules have access to external devices?</h3>
 <p>At this time Native Client modules do not have access to serial ports,
 camera devices, or microphones: Native Client can only use native
 resources that today&#8217;s browsers can access. However, we intend to
 recommend such features to the standards bodies and piggyback on their
 efforts to make these resources available inside the browser.</p>
 <p>You can generally think of Pepper as the C/C++ bindings to the
 capabilities of HTML5. The goal is for Pepper and JavaScript to evolve
 together and stay on par with each other with respect to features and
 capabilities.</p>
-</section></section><section id="security-and-privacy">
 <h2 id="security-and-privacy">Security and Privacy</h2>
-<section id="what-happens-to-my-data-when-i-use-native-client">
 <h3 id="what-happens-to-my-data-when-i-use-native-client">What happens to my data when I use Native Client?</h3>
 <p>Users can opt-in to sending usage statistics and crash information in
 Chrome, which includes usage statistics and crash information about
 Native Client. Crashes in your code won&#8217;t otherwise send your
 information to Google: Google counts the number of such crashes, but
 does so anonymously without sending your application&#8217;s data or its debug
 information.</p>
 <p>For additional information about privacy and Chrome, see the <a class="reference external" href="https://www.google.com/chrome/intl/en/privacy.html">Google Chrome
 privacy policy</a> and the <a class="reference external" href="https://www.google.com/chrome/intl/en/eula_text.html">Google Chrome Terms of Service</a>.</p>
-</section><section id="how-does-native-client-prevent-sandboxed-code-from-doing-bad-things">
 <h3 id="how-does-native-client-prevent-sandboxed-code-from-doing-bad-things">How does Native Client prevent sandboxed code from doing Bad Things?</h3>
 <p>Native Client&#8217;s sandbox works by validating the untrusted code (the
 compiled Native Client module) before running it. The validator checks
 the following:</p>
 <ul class="small-gap">
 <li><strong>Data integrity:</strong> No loads or stores are permitted outside of the
 data sandbox. In particular this means that once loaded into memory,
 the binary is not writable. This is enforced by operating system
 protection mechanisms. While new instructions can be inserted at
 runtime to support things like JIT compilers, such instructions will
 be subject to runtime verification according to the following
 constraints before they are executed.</li>
 <li><strong>No unsafe instructions:</strong> The validator ensures that the Native
 Client application does not contain any unsafe instructions. Examples
 of unsafe instructions are <code>syscall</code>, <code>int</code>, and <code>lds</code>.</li>
 <li><strong>Control flow integrity:</strong> The validator ensures that all direct and
 indirect branches target a safe instruction.</li>
 </ul>
 <p>The beauty of the Native Client sandbox is in reducing &#8220;safe&#8221; code to a
 few simple rules that can be verified by a small trusted validator: the
 compiler isn&#8217;t trusted. The same applies to Portable Native Client where
 even the <code>.pexe</code> to <code>.nexe</code> translator, a simplified compiler
 backend, isn&#8217;t trusted: it is validated before executing, and so is its
 output.</p>
 <p>In addition to static analysis of untrusted code, the Native Client runtime also
 includes an outer sandbox that mediates system calls. For more details about
 both sandboxes, see <a class="reference external" href="http://research.google.com/pubs/pub34913.html">Native Client: A Sandbox for Portable, Untrusted x86 Code</a>
 (PDF).</p>
-</section><section id="how-does-google-know-that-the-safety-measures-in-native-client-are-sufficient">
 <h3 id="how-does-google-know-that-the-safety-measures-in-native-client-are-sufficient">How does Google know that the safety measures in Native Client are sufficient?</h3>
 <p>Google has taken several steps to ensure that Native Client&#8217;s security works,
 including:</p>
 <ul class="small-gap">
 <li>Open source, peer-reviewed papers describing the design.</li>
 <li>A <a class="reference internal" href="/native-client/community/security-contest/index.html"><em>security contest</em></a>.</li>
 <li>Multiple internal and external security reviews.</li>
 <li>The ongoing vigilance of our engineering and developer community.</li>
 </ul>
 <p>Google is committed to making Native Client safer than JavaScript and other
 popular browser technologies. If you have suggestions for security improvements,
 let the team know, by way of the <a class="reference external" href="https://groups.google.com/group/native-client-discuss">native-client-discuss</a> mailing list.</p>
-</section></section><section id="development">
 <h2 id="development">Development</h2>
-<section id="how-do-i-debug">
 <h3 id="how-do-i-debug">How do I debug?</h3>
 <p>Instructions on <a class="reference internal" href="/native-client/sdk/examples.html#debugging-the-sdk-examples"><em>debugging the SDK examples</em></a> using GDB are available. You can also
 debug Native Client modules with some <a class="reference internal" href="/native-client/devguide/devcycle/debugging.html"><em>alternative approaches</em></a>.</p>
-</section><section id="how-do-i-build-x86-32-x86-64-or-arm-nexes">
 <h3 id="how-do-i-build-x86-32-x86-64-or-arm-nexes">How do I build x86-32, x86-64 or ARM <code>.nexes</code>?</h3>
 <p>By default, the applications in the <code>/examples</code> folder create
 architecture-independent <code>.pexe</code> for Portable Native Client. To
 generate a <code>.nexe</code> targetting one specific architecture using the
 Native Client or Portable Native Client toolchains, see the
 <a class="reference internal" href="/native-client/devguide/devcycle/building.html"><em>Building instructions</em></a>.</p>
-</section><section id="how-can-my-web-application-determine-which-nexe-to-load">
 <h3 id="how-can-my-web-application-determine-which-nexe-to-load">How can my web application determine which <code>.nexe</code> to load?</h3>
 <p>Your application does not need to make the decision of loading an
 x86-32, x86-64 or ARM <code>.nexe</code> explicitly&#8212;the Native Client runtime
 examines a manifest file (<code>.nmf</code>) to pick the right <code>.nexe</code> file for
 a given user. You can generate a manifest file using a Python script
 that&#8217;s included in the SDK (see the <code>Makefile</code> in any of the SDK
 examples for an illustration of how to do so). Your HTML file specifies
 the manifest filename in the <code>src</code> attribute of the <code>&lt;embed&gt;</code>
 tag. You can see the way the pieces fit together by examining the
 examples included in the SDK.</p>
-</section><section id="is-it-possible-to-build-a-native-client-module-with-just-plain-c-not-c">
 <h3 id="is-it-possible-to-build-a-native-client-module-with-just-plain-c-not-c">Is it possible to build a Native Client module with just plain C (not C++)?</h3>
 <p>Yes. See the <code>&quot;Hello, World!&quot;</code> in C example in the SDK under
 <code>examples/tutorial/using_ppapi_simple/</code>, or the Game of Life example
 under <code>examples/demo/life/life.c</code>.</p>
-</section><section id="what-unix-system-calls-can-i-make-through-native-client">
 <h3 id="what-unix-system-calls-can-i-make-through-native-client">What UNIX system calls can I make through Native Client?</h3>
 <p>Native Client doesn&#8217;t directly expose any system calls from the host OS
 because of the inherent security risks and because the resulting
 application would not be portable across operating systems. Instead,
 Native Client provides portable cross-OS abstractions wrapping or
 proxying OS functionality or emulating UNIX system calls. For example,
 Native Client provides an <code>mmap()</code> system call that behaves much like
 the standard UNIX <code>mmap()</code> system call.</p>
-</section><section id="is-my-favorite-third-party-library-available-for-native-client">
 <h3 id="is-my-favorite-third-party-library-available-for-native-client">Is my favorite third-party library available for Native Client?</h3>
 <p>Google has ported several third-party libraries to Native Client; such libraries
 are available in the <a class="reference external" href="https://code.google.com/p/naclports">naclports</a> project. We encourage you to contribute
 libraries to naclports, and/or to host your own ported libraries, and to let the
 team know about it on <a class="reference external" href="https://groups.google.com/group/native-client-discuss">native-client-discuss</a> when you do.</p>
-</section><section id="do-all-the-files-in-an-application-need-to-be-served-from-the-same-domain">
 <h3 id="do-all-the-files-in-an-application-need-to-be-served-from-the-same-domain">Do all the files in an application need to be served from the same domain?</h3>
 <p>The <code>.nmf</code>, and <code>.nexe</code> or <code>.pexe</code> files must either be served from the
 same origin as the embedding page or an origin that has been configured
 correctly using <a class="reference external" href="http://en.wikipedia.org/wiki/Cross-origin_resource_sharing">CORS</a>.</p>
 <p>For applications installed from the Chrome Web Store the Web Store manifest
 must include the correct, verified domain of the embedding page.</p>
-</section></section><section id="portability">
 <h2 id="portability">Portability</h2>
-<section id="do-i-have-to-do-anything-special-to-make-my-application-run-on-different-operating-systems">
 <h3 id="do-i-have-to-do-anything-special-to-make-my-application-run-on-different-operating-systems">Do I have to do anything special to make my application run on different operating systems?</h3>
 <p>No. Native Client and Portable Native Client applications run without
 modification on all supported operating systems.</p>
 <p>However, to run on different instruction set architectures (such as
 x86-32, x86-64 or ARM), you currently have to either:</p>
 <ul class="small-gap">
 <li>Use Portable Native Client.</li>
 <li>Build and supply a separate <code>.nexe</code> file for each architecture, and
 make them available on the Chrome Web Store. See <a class="reference internal" href="/native-client/devguide/devcycle/building.html"><em>target
 architectures</em></a> for details about which
 <code>.nexe</code> files will run on which architectures.</li>
 </ul>
-</section><section id="how-easy-is-it-to-port-my-existing-native-code-to-native-client">
 <h3 id="how-easy-is-it-to-port-my-existing-native-code-to-native-client">How easy is it to port my existing native code to Native Client?</h3>
 <p>In most cases you won&#8217;t have to rewrite much, if any, code. The Native
 Client-specific tools, such as <code>pnacl-clang++</code> or <code>x86_64-nacl-g++</code>,
 take care of most of the necessary changes. You may need to make some
 changes to your operating system calls and interactions with external
 devices to work with the web. Porting existing Linux libraries is
 generally straightforward, with large libraries often requiring no
 source change.</p>
 <p>The following kinds of code may be more challenging to port:</p>
 <ul class="small-gap">
 <li>Code that does direct TCP/IP or UDP networking. For security reasons
 these APIs are only available to packaged applications, not on the
 open web, after asking for the appropriate permissions. Native Client
 is otherwise restricted to the networking APIs available in the
 browser.</li>
 <li>Code that creates processes, including UNIX forks. Creating processes
 is not supported for security reasons. However, threads are supported.</li>
 <li>Code that needs to do local file I/O. Native Client is restricted to
 accessing URLs and to local storage in the browser (the Pepper file I/O API
 has access to the same per-application storage that JavaScript has via Local
 Storage). HTML5 File System can be used, among others. For POSIX compatabiliy
 the Native Client SDK includes a library called nacl_io which allows the
 application to interact with all these types of files via standard POSIX I/O
 functions (e.g. open/fopen/read/write/...). See <a class="reference internal" href="/native-client/devguide/coding/nacl_io.html"><em>Using NaCl I/O</em></a> for more details.</li>
 </ul>
-</section></section><section id="troubleshooting">
-<span id="faq-troubleshooting"></span><h2 id="troubleshooting"><span id="faq-troubleshooting"></span>Troubleshooting</h2>
-<section id="my-pexe-isn-t-loading-help">
+<h2 id="troubleshooting"><span id="faq-troubleshooting"></span>Troubleshooting</h2>
 <h3 id="my-pexe-isn-t-loading-help">My <code>.pexe</code> isn&#8217;t loading, help!</h3>
 <ul class="small-gap">
 <li>You must use Google Chrome version 31 or greater for Portable Native
 Client. Make sure you have Portable Native Client installed in
 <code>about:nacl</code>; if not open <code>about:components</code> and &#8220;Check for
 update&#8221; for PNaCl.</li>
 <li>PNaCl <code>.pexe</code> must be compiled with pepper_31 SDK or higher (earlier
 SDK versions had experimental support for PNaCl, now deprecated).</li>
 <li>Your application can verify that Portable Native Client is supported
 in JavaScript with <code>navigator.mimeTypes['application/x-pnacl'] !==
 undefined</code>. This is preferred over checking the Chrome version.</li>
 </ul>
-</section><section id="my-nexe-files-never-finish-loading-what-gives">
 <h3 id="my-nexe-files-never-finish-loading-what-gives">My <code>.nexe</code> files never finish loading. What gives?</h3>
 <p>Here are ways to resolve some common problems that can prevent loading:</p>
 <ul class="small-gap">
 <li>You must use Google Chrome version 14 or greater for Native Client.</li>
 <li>If you haven&#8217;t already done so, enable the Native Client flag in
 Google Chrome. Type <code>about:flags</code> in the Chrome address bar, scroll
 down to &#8220;Native Client&#8221;, click the &#8220;Enable&#8221; link, scroll down to the
 bottom of the page, and click the &#8220;Relaunch Now&#8221; button (all browser
 windows will restart).</li>
 <li>Verify that the Native Client plugin is enabled in Google Chrome. Type
@@ skipping 12 matching lines @@
 greater.</li>
 <li>You must load the correct <code>.nexe</code> file for your machine&#8217;s specific
 instruction set architecture (x86-32, x86-64 or ARM). You can ensure
 you&#8217;re loading the correct <code>.nexe</code> file by building a separate
 <code>.nexe</code> for each architecture, and using a <code>.nmf</code> manifest file to
 let the browser select the correct <code>.nexe</code> file. Note: the need to
 select a processor-specific <code>.nexe</code> goes away with Portable Native
 Client.</li>
 <li>If things still aren&#8217;t working, <a class="reference internal" href="/native-client/help.html"><em>ask for help</em></a>!</li>
 </ul>
-</section></section></section>
+</section>
 
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