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[[Thomas_Schwinge|tschwinge]] has written a shell script for building a
complete cross-build environment for GNU/Hurd systems.

Find it in the [[source_repositories/incubator]], *cross-gnu* branch.


# Using

Read through it.  Understand it.  Only then use it by following the next steps.


# Status

/!\ Please note that these cross toolchains does not yet encompass all of the
functionality that native toolchains provide.  For example, there is only
support for C and C++ so far, but not for other languages.  A bunch of fixes /
enhancements of [[glibc]] are missing.  We're working towards minimizing these
differences, as well as towards pushing all patches upstream.


## Supported Versions of Source Packages

The following ones are known to work.  Others may work as well, but no
guarantee is given.  Always the preferred version is listed first.

  * [[`src/binutils`|binutils]]

      * CVS `binutils-2_20-branch`

            $ mkdir binutils-2_20-branch
            $ cd binutils-2_20-branch/
            $ cvs -d:pserver:anoncvs@sources.redhat.com:/cvs/src ↩
                co -r binutils-2_20-branch binutils

        The sources are rooted in `binutils-2_20-branch/src/`.  Also use the above
        commands for updating, instead of the usual `cvs update`.

      * Release of the 2.20 series from <ftp://ftp.gnu.org/gnu/binutils/>
        should also be fine.

  * [[`src/gcc`|gcc]]

      * SVN `gcc-4_5-branch`

            $ svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-4_5-branch

        Patches:

          * <http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00602.html>

        Prepare:

            $ ( cd gcc-4_5-branch/ && contrib/gcc_update --touch )

      * SVN `gcc-4_4-branch`

            $ svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-4_4-branch

        Patches:

          * <http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00602.html>

        Prepare:

            $ ( cd gcc-4_4-branch/ && contrib/gcc_update --touch )

      * Releases of the 4.5 and 4.4 series from <ftp://ftp.gnu.org/gnu/gcc/>
        should also be fine, but need the same set of patches as the
        `gcc-4_5-branch` needs.

  * [[`src/gnumach`|microkernel/mach/gnumach]]

      * Git `master` branch

            $ git clone ↩
                git://git.sv.gnu.org/hurd/gnumach.git gnumach

        Prepare:

            $ ( cd gnumach/ && autoreconf -vi )

  * [[`src/mig`|microkernel/mach/mig/gnu_mig]]

      * Git `master` branch

            $ git clone ↩
                git://git.sv.gnu.org/hurd/mig.git mig

        Prepare:

            $ ( cd mig/ && autoreconf -vi )

  * [[`src/hurd`|hurd]]

      * Git `master` branch

            $ git clone ↩
                git://git.sv.gnu.org/hurd/hurd.git hurd

  * [[`src/libpthread`|libpthread]]

      * Git `tschwinge/Peter_Herbolzheimer` branch

            $ git clone --no-checkout ↩
                git://git.sv.gnu.org/hurd/libpthread.git libpthread
            $ cd libpthread/
            $ git checkout origin/tschwinge/Peter_Herbolzheimer

  * [[`src/glibc`|glibc]]

      * Git `tschwinge/Roger_Whittaker` branch

            $ git clone --no-checkout ↩
                git://git.sv.gnu.org/hurd/glibc.git glibc
            $ cd glibc/
            $ git checkout origin/tschwinge/Roger_Whittaker

<!--

  * [[`src/gdb`|gdb]]

    This is optional and will only be compiled if present.

      * CVS `gdb_6_6-branch`

            $ cvs -d:pserver:anoncvs@sources.redhat.com:/cvs/src ↩
              co -r gdb_6_6-branch gdb
            $ mv src gdb_6_6-branch

        Also needs some patch because of MIG changes, if I remember correctly.

      * Recent tarballs from <ftp://ftp.gnu.org/gnu/gdb/> should also work.

-->


## Preparation

Unpack the tarballs if you downloaded any.

Create a directory where the cross build shall be rooted in and a `src`
subdirectory in there.  Then create symbolic links for every of the above
packages: from `src/PACKAGE` to where you stored or unpacked it.  If you don't
intend to build several cross compilers or use the source trees otherwise, you
can also directly store the source trees in `src/`.  The source trees can be
shared between multiple cross build trees since the packages' build systems are
supposed not to modify the files in the source trees.  Not all packages adhere
to that, but they fail to do so only for pre-processed documentation, etc.

Either make sure that `cross-gnu-env` and `cross-gnu` are found in `$PATH`
(`~/bin/`, for example) or alternatively remember to use their full paths in
the following.

The system you're running the script on (the *build* system) needs to have a
basic compiling environment installed, i.e., a C compiler with the basic
libraries and `make`.  You might also need `flex` and `bison`.  For building
recent version of GCC (4.3 onwards)
you'll need to have development packages of GMP and MPFR installed.


## Setting Up the Environment

Do this every time you intend to use the cross compiler:

    $ ROOT=to/the/cross/build/root
    $ . cross-gnu-env

This will set several environment variables, which are later used by (a) the
`cross-gnu` script and (b) by you, the user of the cross compiler.  `$TARGET`
will be set by the script, `$PATH` will be adjusted, etc.  See the
`cross-gnu-env` file for all environment variables that are set, as well as
their default values.  `$ROOT` will be made an absolute path if it isn't
already.

Later, you'll be able to do things like `../configure --host="$TARGET"` and the
cross compiler will be found automatically.


## Creating the Cross Build Environment

After setting up the environemt, just run `cross-gnu` and watch the messages
flow by.  In the end you should see a message: *[...]/cross-gnu: Everything
should be in place now.*


## Staying Up-To-Date

You can re-run `cross-gnu` to rebuild the parts of the sources that have
changed since the last run.  This will save a lot of time compared to starting
from scratch again.  Also, it is especially useful if you aren't working with
unpacked tarballs, but on CVS's / SVN's / Git's branches or want to quickly get
a new toolchain
with patches you applied to the source trees.  However: do *not* use this
technique when doing major changes to the source trees, like switching from GCC
4.4 to GCC 4.5.