NaCl docs: add project ideas

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+<section id="contributor-ideas">
+<span id="ideas"></span><h1 id="contributor-ideas"><span id="ideas"></span>Contributor Ideas</h1>
+<div class="contents local" id="contents" style="display: none">
+<ul class="small-gap">
+<li><a class="reference internal" href="#contributing-me" id="id8">Contributing? Me‽</a></li>
+<li><p class="first"><a class="reference internal" href="#id1" id="id9">Ideas</a></p>
+<ul class="small-gap">
+<li><p class="first"><a class="reference internal" href="#ports" id="id10">Ports</a></p>
+<ul class="small-gap">
+<li><a class="reference internal" href="#new-filesystems" id="id11">New Filesystems</a></li>
+<li><a class="reference internal" href="#open-source-porting" id="id12">Open Source Porting</a></li>
+</ul>
+</li>
+<li><p class="first"><a class="reference internal" href="#languages" id="id13">Languages</a></p>
+<ul class="small-gap">
+<li><a class="reference internal" href="#rust" id="id14">Rust</a></li>
+<li><a class="reference internal" href="#haskell" id="id15">Haskell</a></li>
+<li><a class="reference internal" href="#julia" id="id16">Julia</a></li>
+<li><a class="reference internal" href="#scala" id="id17">Scala</a></li>
+<li><a class="reference internal" href="#elm" id="id18">Elm</a></li>
+<li><a class="reference internal" href="#mono" id="id19">Mono</a></li>
+<li><a class="reference internal" href="#perl" id="id20">Perl</a></li>
+</ul>
+</li>
+<li><a class="reference internal" href="#tcc" id="id21">TCC</a></li>
+<li><p class="first"><a class="reference internal" href="#llvm-and-pnacl" id="id22">LLVM and PNaCl</a></p>
+<ul class="small-gap">
+<li><a class="reference internal" href="#sandboxing-optimizations" id="id23">Sandboxing Optimizations</a></li>
+<li><a class="reference internal" href="#binary-size-reduction" id="id24">Binary Size Reduction</a></li>
+<li><a class="reference internal" href="#vector-support" id="id25">Vector Support</a></li>
+<li><a class="reference internal" href="#atomics" id="id26">Atomics</a></li>
+<li><a class="reference internal" href="#security-enhanced-pnacl" id="id27">Security-enhanced PNaCl</a></li>
+</ul>
+</li>
+<li><p class="first"><a class="reference internal" href="#nacl" id="id28">NaCl</a></p>
+<ul class="small-gap">
+<li><a class="reference internal" href="#auto-sandboxing" id="id29">Auto-Sandboxing</a></li>
+<li><a class="reference internal" href="#new-sandbox" id="id30">New Sandbox</a></li>
+<li><a class="reference internal" href="#bit-sandbox" id="id31">64-bit Sandbox</a></li>
+</ul>
+</li>
+</ul>
+</li>
+</ul>
+
+</div><h2 id="contributing-me">Contributing? Me‽</h2>
+<p>NaCl and PNaCl are very big projects: they expose an entire operating system to
+developers, interact with all of the Web platform, and deal with compilers
+extensively to allow code written in essentially any programming language to
+execute on a variety of CPU architectures. This can be daunting when trying to
+figure out how to contribute to the open-source project! This page tries to make
+contributing easier by listing project ideas by broad area of interest, and
+detailing the required experience and expectations for each idea.</p>
+<p>This isn&#8217;t meant to constrain contributions! If you have ideas that aren&#8217;t on
+this page please contact the <a class="reference external" href="https://groups.google.com/group/native-client-discuss">native-client-discuss</a> mailing list.</p>
+<p>If you like an idea on this page and would like to get started, contact the
+<a class="reference external" href="https://groups.google.com/group/native-client-discuss">native-client-discuss</a> mailing list so that we can help you find a mentor.</p>
+<h2 id="id1">Ideas</h2>
+<p>We&#8217;ve separated contributor ideas into broad areas of interest:</p>
+<ul class="small-gap">
+<li><strong>Ports</strong> encompass all the code that <em>uses</em> the PNaCl platform. Put simply,
+the point of ports is to make existing open-source code work.</li>
+<li><strong>Programming languages</strong> sometimes involves compiler work, and sometimes
+requires getting an interpreter and its APIs to work well within the Web
+platform.</li>
+<li><strong>LLVM and PNaCl</strong> requires compiler work: PNaCl is based on the LLVM
+toolchain, and most of the work in this area would occur in the upstream LLVM
+repository.</li>
+<li><strong>NaCl</strong> mostly deals with low-level systems work and security.</li>
+</ul>
+<h3 id="ports">Ports</h3>
+<h4 id="new-filesystems">New Filesystems</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Expose new filesystems to <a class="reference internal" href="/native-client/devguide/coding/nacl_io.html"><em>nacl_io</em></a>.</li>
+<li><strong>Brief explanation:</strong> nacl_io exposes filesystems like html5fs and RAM disk,
+which can be mounted and then accessed through regular POSIX APIs. New types
+of filesystems could be exposed in a similar way, allowing developers to build
+apps that &#8220;just work&#8221; on the Web platform while using Web APIs. A few ideas
+include connecting to: Google Drive, Github, Dropbox.</li>
+<li><strong>Expected results:</strong> A new filesystem is mountable using nacl_io, is well
+tested, and used in a demo application.</li>
+<li><strong>Knowledge Prerequisite:</strong> C++.</li>
+<li><strong>Mentor:</strong> Sam Clegg.</li>
+</ul>
+<h4 id="open-source-porting">Open Source Porting</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Port substantial open source projects to work in naclports.</li>
+<li><strong>Brief explanation:</strong> naclports contains a large collection of open source
+projects that properly compile and run on the PNaCl platform. This project
+involves adding new useful projects to naclports, and upstreaming any patches
+to the original project: running on PNaCl effective involves porting to a new
+architecture and operating system. Project ideas include: Gimp, Inkscape, Gtk.</li>
+<li><strong>Expected results:</strong> New open source projects are usable from naclports.</li>
+<li><strong>Knowledge Prerequisite:</strong> C/C++.</li>
+<li><strong>Mentor:</strong> Brad Nelson.</li>
+</ul>
+<h3 id="languages">Languages</h3>
+<p>PNaCl already has support for C and C++, and virtual machines such as
+JavaScript, Lua, Python and Ruby. We&#8217;d like to support more languages, either by
+having these languages target LLVM bitcode or by making sure that the language
+virtual machine&#8217;s APIs work well on the Web platform.</p>
+<h4 id="rust">Rust</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support the Rust programming languages.</li>
+<li><strong>Brief explanation:</strong> The <a class="reference external" href="http://www.rust-lang.org">Rust</a> programming language uses LLVM. The aim of
+this project is to allow it to deliver PNaCl <code>.pexe</code> files.</li>
+<li><strong>Expected results:</strong> The Rust test suite passes within the browser. How to
+use Rust to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, LLVM.</li>
+<li><strong>Mentor:</strong> Ben Smith.</li>
+</ul>
+<h4 id="haskell">Haskell</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support the Haskell programming language.</li>
+<li><strong>Brief explanation:</strong> <a class="reference external" href="http://www.haskell.org/ghc/docs/latest/html/users_guide/code-generators.html">GHC</a> targets LLVM. The aim of this project is to allow
+it to deliver PNaCl <code>.pexe</code> files. One interesting difficulty will be to
+ensure that tail call optimization occurs properly in all targets.</li>
+<li><strong>Expected results:</strong> The Haskell test suite passes within the browser. How to
+use Haskell to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, LLVM.</li>
+<li><strong>Mentor:</strong> Ben Smith.</li>
+</ul>
+<h4 id="julia">Julia</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support the Julia programming language.</li>
+<li><strong>Brief explanation:</strong> <a class="reference external" href="http://julialang.org">Julia</a> targets LLVM, but it does so through LLVM&#8217;s
+Just-in-Time compiler which PNaCl doens&#8217;t support. The aim of this project is
+to allow it to deliver PNaCl <code>.pexe</code> files.</li>
+<li><strong>Expected results:</strong> The Julia test suite passes within the browser. How to
+use Julia to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, LLVM.</li>
+<li><strong>Mentor:</strong> Ben Smith.</li>
+</ul>
+<h4 id="scala">Scala</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support the Scala programming language.</li>
+<li><strong>Brief explanation:</strong> The aim of this project is to allow <a class="reference external" href="http://www.scala-lang.org">Scala</a> to deliver
+PNaCl <code>.pexe</code> files.</li>
+<li><strong>Expected results:</strong> The Scala test suite passes within the browser. How to
+use Scala to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers.</li>
+<li><strong>Mentor:</strong> Ben Smith.</li>
+</ul>
+<h4 id="elm">Elm</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support the Elm programming language.</li>
+<li><strong>Brief explanation:</strong> The aim of this project is to allow <a class="reference external" href="http://elm-lang.org">Elm</a> to deliver
+PNaCl <code>.pexe</code> files.</li>
+<li><strong>Expected results:</strong> The Elm test suite passes within the browser. How to use
+Elm to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers.</li>
+<li><strong>Mentor:</strong> Jan Voung.</li>
+</ul>
+<h4 id="mono">Mono</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support C# running inside Mono.</li>
+<li><strong>Brief explanation:</strong> C# is traditionally a Just-in-Time compiled language,
+the aim of this project is to be able to run C# code withing <a class="reference external" href="http://www.mono-project.com">Mono</a> while
+compiling ahead-of-time.</li>
+<li><strong>Expected results:</strong> The Mono test suite passes within the browser. How to
+use Mono to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers.</li>
+<li><strong>Mentor:</strong> Derek Schuff.</li>
+</ul>
+<h4 id="perl">Perl</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Support Perl.</li>
+<li><strong>Brief explanation:</strong> Port the Perl programming language and its packages to
+the PNaCl platform.</li>
+<li><strong>Expected results:</strong> The Perl test suite passes within the browser. How to
+use Perl to target PNaCl is well documented and easy to do.</li>
+<li><strong>Knowledge Prerequisite:</strong> C.</li>
+<li><strong>Mentor:</strong> Brad Nelson.</li>
+</ul>
+<h3 id="tcc">TCC</h3>
+<ul class="small-gap">
+<li><strong>Project:</strong> Port Fabrice Ballard&#8217;s Tiny C Compiler _TCC to NaCl and PNaCl.</li>
+<li><strong>Brief explanation:</strong> Port TCC to NaCl and enhance to follow NaCl sandboxing
+rule, as well as emitting PNaCl bitcode. The same could be done with <a class="reference external" href="https://code.google.com/p/picoc">Pico
+C</a>.</li>
+<li><strong>Expected results:</strong> Compiler ported and code generator working. Can run a
+small benchmark of your choice.</li>
+<li><strong>Knowledge Prerequisite:</strong> C, assembly, compilers.</li>
+</ul>
+<h3 id="llvm-and-pnacl">LLVM and PNaCl</h3>
+<p>PNaCl relies heavily on LLVM in two key areas:</p>
+<ul class="small-gap">
+<li>On the developer&#8217;s machine, LLVM is used as a regular toolchain to parse code,
+optimize it, and create a portable executable.</li>
+<li>On user devices, LLVM is installed as part of Chrome to translate a portable
+executable into a machine-specific sandboxed executable.</li>
+</ul>
+<p>Most of the contribution ideas around LLVM would occur in the upstream LLVM
+repository, and would improve LLVM for more than just PNaCl&#8217;s sake (though PNaCl
+is of course benefiting from these improvements!). Some of these ideas would
+also apply to <a class="reference external" href="https://chromium.googlesource.com/native_client/pnacl-subzero/+/master/README.rst">Subzero</a>, a small and fast translator from portable executable to
+machine-specific code.</p>
+<h4 id="sandboxing-optimizations">Sandboxing Optimizations</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Improved sandboxed code generation.</li>
+<li><strong>Brief explanation:</strong> PNaCl generates code that targets the NaCl sandbox, but
+this code generation isn&#8217;t always optimal and sometimes results in a
+performance lost of 10% to 25% compared to unsandboxed code. This project
+would require looking at the x86-32, x86-64, ARM and MIPS code being generated
+by LLVM or Subzero and figuring out how it can be improved to execute
+faster. As an example, one could write a compiler pass to figure out when
+doing a zero-extending <code>lea</code> on NaCl x86-64 would be useful (increment and
+sandbox), or see if <code>%rbp</code> can be used more for loads/stores unrelated to
+the call frame.</li>
+<li><strong>Expected results:</strong> Sandboxed code runs measurably faster, and gets much
+closer to unsandboxed code performance. PNaCl has a fairly extensive
+performance test suite to measure these improvements.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, assembly.</li>
+<li><strong>Mentor:</strong> Jan Voung.</li>
+</ul>
+<h4 id="binary-size-reduction">Binary Size Reduction</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Reduce the size of binaries generated by LLVM.</li>
+<li><strong>Brief explanation:</strong> This is generally useful for the LLVM project, but is
+especially important for PNaCl and Emscripten because we deliver code on the
+Web (transfer size and compile time matter!). This stands to drastically
+improve transfer time, and load time. Reduces the size of the PNaCl translator
+as well as user code, makes the generated portable executables smaller and
+translation size faster. Improve LLVM’s <code>mergefuncs</code> pass to reduce
+redundancy of code. Detect functions and data that aren’t used. Improve
+partial evaluation: can e.g. LLVM’s command-line parsing be mostly removed
+from the PNaCl translator?  Potentially add a pass where a developer manually
+marks functions as unused, and have LLVM replace them with <code>abort</code> (this
+should propagate and mark other code as dead). This list could be created by
+using code coverage information.</li>
+<li><strong>Expected results:</strong> Portable executables in the PNaCl repository are
+measurably smaller and translate faster.</li>
+<li><strong>Knowledge Prerequisite:</strong> LLVM bitcode.</li>
+<li><strong>Mentor:</strong> JF Bastien.</li>
+</ul>
+<h4 id="vector-support">Vector Support</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Improve PNaCl SIMD support.</li>
+<li><strong>Brief explanation:</strong> PNaCl offers speed on the Web, and generating good SIMD
+code allows developers to use the full capabilities of the device (better user
+experience, longer battery life). The goal of this project is to allow
+developers to use more hardware features in a portable manner by exposing
+portable SIMD primitives and using auto-vectorization. This could also mean
+making the architecture-specific intrinsics “just work” within PNaCl (lower
+them to equivalent architecture-independent intrinsics).</li>
+<li><strong>Expected results:</strong> Sample code and existing applications run measurably
+faster by using portable SIMD and/or by auto-vectorizing.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, high-performance code tuning.</li>
+<li><strong>Mentor:</strong> JF Bastien.</li>
+</ul>
+<h4 id="atomics">Atomics</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Improve the performance of C++11 atomics.</li>
+<li><strong>Brief explanation:</strong> C++11 atomics allow programmers to shed inline assembly
+and use language-level features to express high-performance code. This is
+great for portability, but atomics currently aren&#8217;t as fast as they could be
+on all platforms. We had an intern work on this in the summer of 2014, see his
+LLVM developer conference presentation <a class="reference external" href="http://llvm.org/devmtg/2014-10/#talk10">Blowing up the atomic barrier</a>. This
+project would be a continuation of this work: improve LLVM&#8217;s code generation
+for atomics.</li>
+<li><strong>Expected results:</strong> Code using C++11 atomics runs measurably faster on
+different architectures.</li>
+<li><strong>Knowledge Prerequisite:</strong> Compilers, memory models.</li>
+<li><strong>Mentor:</strong> JF Bastien.</li>
+</ul>
+<h4 id="security-enhanced-pnacl">Security-enhanced PNaCl</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Security in-depth for PNaCl.</li>
+<li><strong>Brief explanation:</strong> PNaCl brings native code to the Web, and we want to
+improve the security of the platform as well as explore novel mitigations.
+This allows PNaCl to take better advantage of the hardware and operating
+system it&#8217;s running on and makes the platform even faster while keeping users
+safe. It’s also useful for non-browser uses of PNaCl such as running untrusted
+code in the Cloud. A few areas to explore are: code randomization for LLVM and
+Subzero, fuzzing of the translator, code hiding at compilation time, and code
+tuning to the hardware and operating system the untrusted code is running on.</li>
+<li><strong>Expected results:</strong> The security design and implementation successfully pass
+a review with the Chrome security team.</li>
+<li><strong>Knowledge Prerequisite:</strong> Security.</li>
+<li><strong>Mentor:</strong> JF Bastien.</li>
+</ul>
+<h3 id="nacl">NaCl</h3>
+<h4 id="auto-sandboxing">Auto-Sandboxing</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Auto-sandboxing assembler.</li>
+<li><strong>Brief explanation:</strong> NaCl has a toolchain which can sandbox native
+code. This toolchain can consume C/C++ as well as pre-sandboxed assembly, or
+assembly which uses special sandboxing macros. The goal of this project is to
+follow NaCl&#8217;s sandboxing requirements automatically which compiling assembly
+files.</li>
+<li><strong>Expected results:</strong> Existing assembly code can be compiled to a native
+executable that follows NaCl&#8217;s sandboxing rules.</li>
+<li><strong>Knowledge Prerequisite:</strong> Assemblers.</li>
+<li><strong>Mentor:</strong> Derek Schuff, Roland McGrath.</li>
+</ul>
+<h4 id="new-sandbox">New Sandbox</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Create a new software-fault isolation sandbox.</li>
+<li><strong>Brief explanation:</strong> NaCl pioneered production-quality sandboxes based on
+software-fault isolation, and currently supports x86-32, x86-64, ARMv7&#8217;s ARM,
+and MIPS. This project involves designing and implementing new sandboxes. Of
+particular interest are ARMv8&#8217;s aarch64 and Power8. This also requires
+implementing sandboxing in the compiler.</li>
+<li><strong>Expected results:</strong> The new sandbox&#8217;s design and implementation successfully
+pass a review with the Chrome security team. Existing NaCl code successfully
+runs in the new sandbox.</li>
+<li><strong>Knowledge Prerequisite:</strong> Security, low-level assembly, compilers, LLVM.</li>
+<li><strong>Mentor:</strong> David Sehr.</li>
+</ul>
+<h4 id="bit-sandbox">64-bit Sandbox</h4>
+<ul class="small-gap">
+<li><strong>Project:</strong> Create a 64-bit sandbox.</li>
+<li><strong>Brief explanation:</strong> NaCl currently supports sandboxes where pointers are
+32-bits. Some applications, both in-browser and not in-browser, would benefit
+from a larger address space. This project involves designing and implementing
+a model for 64-bit sandboxes on all architecture NaCl currently supports. This
+also requires supporting 64-bit pointers in PNaCl using the <code>le64</code> platform,
+and updating the code generation for each platform.</li>
+<li><strong>Expected results:</strong> The new sandbox&#8217;s design and implementation successfully
+pass a review with the Chrome security team. Existing NaCl code successfully
+runs in the new sandbox.</li>
+<li><strong>Knowledge Prerequisite:</strong> Security, low-level assembly, compilers, LLVM.</li>
+<li><strong>Mentor:</strong> David Sehr.</li>
+</ul>
+</section>
+
+{{/partials.standard_nacl_article}}