Attachment 77871 Details for Bug 116575 – cross-compiling-distcc.xml

cross-compiling-distcc.xml

cross-compiling-distcc.xml (text/plain), 7.20 KB, created by nm (RETIRED) on 2006-01-22 17:02:46 UTC

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><?xml version="1.0" encoding="UTF-8"?>
><!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
>
>
><guide link="/doc/en/cross-compiling-distcc.xml">
><title>DistCC Cross-compiling Guide</title>
>
><author title="Author">
>  <mail link="agaffney@gentoo.org">Andrew Gaffney</mail>
></author>
><author title="Editor">
>  <mail link="jackdark@gmail.com">Joshua Saddler</mail>
></author>
>
><abstract>
>This guide shows you how to set up distcc for cross-compiling across different
>processor architectures.
></abstract>
>
>
>
><license/>
>
><version>1.0</version>
><date>2006-01-22</date>
>
><chapter>
><title>Cross-compiling with distcc</title>
><section>
><title>Introduction</title>
><body>
>
><p>
><c>distcc</c> is a tool that lets you share the burden of software compiling
>across several networked computers. As long as the networked boxes are all using
>the same toolchain built for the same processor architecture, no special
><c>distcc</c> setup is required. But what do you do if you need to compile for a
>different architecture using differing computers? This guide will show you how
>to configure <c>distcc</c> to compile for different architectures.
></p>
>
></body>
></section>
><section>
><title>Emerge the needed utilities</title>
><body>
>
><p>
>First, you will need to emerge <c>crossdev</c> on all the machines that will be
>involved in the compiling process. <c>crossdev</c> is a tool that makes building
>cross-architecture toolchains easy. It was originally written by <mail
>link="kumba@gentoo.org">Joshua Kinard</mail> and was re-written from the ground
>up by <mail link="vapier@gentoo.org">Mike Frysinger</mail>. Its usage is
>straightforward: <c>crossdev -t sparc</c> will build a full cross-toolchain
>targetting the Sparc architecture. This includes binutils, gcc, glibc, and
>linux-headers. If you need more help, try running <c>crossdev --help</c>.
>Obviously, you will need to emerge the proper cross-toolchain on all the helper
>boxes.
></p>
>
><p>
>Next, you will need to emerge <c>distcc</c> on all the machines that will be
>involved in the process. This includes the box that will run emerge and the
>boxes with the cross-compilers. Please see the <uri
>link="/doc/en/distcc.xml">Gentoo Distcc Documentation</uri> for more
>information on setting up and using <c>distcc</c>.
></p>
>
></body>
></section>
><section>
><title>Arch-specific notes</title>
><body>
>
><p>
>If you are cross-compiling between different subarchitectures for Intel x86
>(e.g. i586 and i686), you must still build a full cross-toolchain for the
>desired CHOST, or else the compilation will fail. This is because i586 and i686
>are actually different CHOSTs, despite the fact that they are both considered
>"x86." Please keep this in mind when you build your cross-toolchains. For
>example, if the target box is i586, this means that you must build i586
>cross-toolchains on your i686 helper boxes.
></p>
>
></body>
></section>
><section>
><title>Configuring distcc to cross-compile correctly</title>
><body>
>
><p>
>In the default distcc setup, cross-compiling will <e>not</e> work properly. The
>problem is that many builds just call <c>gcc</c> instead of the full compiler
>name (e.g. <c>sparc-unknown-linux-gnu-gcc</c>). When this compile gets
>distributed to a distcc helper box, the native compiler gets called instead of
>your shiny new cross-compiler.
></p>
>
><p>
>Fortunately, there is a workaround for this little problem. All it takes is a
>wrapper script and a few symlinks on the box that will be running
><c>emerge</c>. I'll use my Sparc box as an example. Wherever you see
><c>sparc-unknown-linux-gnu</c> below, you will want to insert your own CHOST
>(<c>x86_64-pc-linux-gnu</c> for an AMD64 box, for example). When you first
>emerge distcc, the <path>/usr/lib/distcc/bin</path> directory looks like this:
></p>
>
><note>
>The following instructions are to be performed only on the box running the
>emerge. Do not perform these steps on the helper boxes.
></note>
>
><pre caption="Available compilers">
>$ <i>ls -l</i>
>total 0
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 c++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 cc -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 g++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 gcc -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 sparc-unknown-linux-gnu-c++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 sparc-unknown-linux-gnu-g++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Dec 23 20:13 sparc-unknown-linux-gnu-gcc -&gt; /usr/bin/distcc
></pre>
>
><p>
>Here is what you want to do:
></p>
>
><pre caption="Modifying distcc">
># <i>rm c++ g++ gcc cc</i>
></pre>
>
><p>
>Next, we'll create the new script on this box. Fire up your favorite editor and
>create a file with the following text in it, then save it as
><path>sparc-unknown-linux-gnu-wrapper</path>. Remember to change the CHOST (in
>this case, <c>sparc-unknown-linux-gnu</c>) to the actual CHOST of the box that
>will be running the emerge.
></p>
>
><pre caption="The new wrapper script">
>#!/bin/bash
>
>exec /usr/lib/distcc/bin/sparc-unknown-linux-gnu-${0##*/} "$@"
></pre>
>
><p>
>Next, we'll make the script executable and create the proper symlinks:
></p>
>
><pre caption="Creating the symlinks">
># <i>chmod a+x sparc-unknown-linux-gnu-wrapper</i>
># <i>ln -s /usr/bin/distcc sparc-unknown-linux-gnu-cc</i>
># <i>ln -s sparc-unknown-linux-gnu-wrapper gcc</i>
># <i>ln -s sparc-unknown-linux-gnu-wrapper cc</i>
># <i>ln -s sparc-unknown-linux-gnu-wrapper c++</i>
># <i>ln -s sparc-unknown-linux-gnu-wrapper g++</i>
></pre>
>
><p>
>When you're done, <path>/usr/lib/distcc/bin</path> will look like this:
></p>
>
><pre caption="A proper set of compilers">
>$ <i>ls -l</i>
>total 4
>lrwxrwxrwx  1 root root 25 Jan 18 14:20 c++ -&gt; sparc-unknown-linux-gnu-wrapper
>lrwxrwxrwx  1 root root 25 Jan 18 14:20 cc -&gt; sparc-unknown-linux-gnu-wrapper
>lrwxrwxrwx  1 root root 25 Jan 18 14:20 g++ -&gt; sparc-unknown-linux-gnu-wrapper
>lrwxrwxrwx  1 root root 25 Jan 18 14:20 gcc -&gt; sparc-unknown-linux-gnu-wrapper
>lrwxrwxrwx  1 root root 15 Nov 21 10:42 sparc-unknown-linux-gnu-c++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Jan 18 14:20 sparc-unknown-linux-gnu-cc -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Nov 21 10:42 sparc-unknown-linux-gnu-g++ -&gt; /usr/bin/distcc
>lrwxrwxrwx  1 root root 15 Jul 27 10:52 sparc-unknown-linux-gnu-gcc -&gt; /usr/bin/distcc
>-rwxr-xr-x  1 root root 70 Jan 18 14:20 sparc-unknown-linux-gnu-wrapper
></pre>
>
><p>
>Congratulations; you now have a (hopefully) working cross-distcc setup.
></p>
>
></body>
></section>
><section>
><title>How this works</title>
><body>
>
><p>
>When <c>distcc</c> is called, it checks to see what it was called as (e.g.
><c>i686-pc-linux-gnu-gcc</c>, <c>sparc-unknown-linux-gnu-g++</c>, etc). When
>distcc then distributes the compile to a helper box, it passes along the name
>it was called as. The distcc daemon on the other helper box then looks for a
>binary with that same name. If it sees just <c>gcc</c>, it will look for
><c>gcc</c>, which is likely to be the native compiler on the helper box, if it
>is not the same architecture as the box running <c>emerge</c>. When the
><e>full</e> name of the compiler is sent (e.g.
><c>sparc-unknown-linux-gnu-gcc</c>), there is no confusion.
></p>
>
></body>
></section>
></chapter>
></guide>

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