`cross-gnu`

Thomas Schwinge has written a shell script for building a complete cross-build environment for GNU/Hurd systems.

For now, find the shell scripts at http://nic-nac-project.de/~schwinge/tmp/cross-gnu and http://nic-nac-project.de/~schwinge/tmp/cross-gnu-env.

Using

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

$/!\$ Be made aware that -- while it is of course possible to build a working cross-compiler -- this is not trivial to do. You'll have to patch source packages. See the following list about needed patches, which have not yet been installed in the upstream repositories.

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: GNU Binutils
- CVS binutils-2_18-branch
```
$ mkdir binutils-2_18-branch
$ cd binutils-2_18-branch
$ cvs -d:pserver:anoncvs@sources.redhat.com:/cvs/src \
    co -r binutils-2_18-branch binutils
```
  The sources are rooted in binutils-2_18-branch/src/. Also use these commands for updating, instead of the usual cvs update.
- The 2.18 release tarball from ftp://ftp.gnu.org/gnu/binutils/ should also be fine, as should be all other recent releases.
src/gcc: GNU Compiler Collection
- SVN gcc-4_1-branch
```
$ svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-4_1-branch
```
  Prepare:
```
$ ( cd gcc-4_1-branch/ && contrib/gcc_update --touch )
```
- Recent releases of the 4.1 series from ftp://ftp.gnu.org/gnu/gcc/ should also be fine.
- SVN gcc-4_2-branch
```
$ svn co svn://gcc.gnu.org/svn/gcc/branches/gcc-4_2-branch
```
  Prepare:
```
$ ( cd gcc-4_2-branch/ && contrib/gcc_update --touch )
```
  - Patches: http://lists.gnu.org/archive/html/bug-hurd/2007-11/msg00034.html
- Recent releases of the 4.2 series from ftp://ftp.gnu.org/gnu/gcc/ should also be fine, but need the same set of patches as the gcc-4_2-branch needs.
- SVN trunk -- upcoming 4.3 series
```
$ svn co svn://gcc.gnu.org/svn/gcc/trunk
```
  Prepare:
```
$ ( cd trunk/ && contrib/gcc_update --touch )
```
  - Patches: http://lists.gnu.org/archive/html/bug-hurd/2007-12/msg00029.html

src/gnumach: GNU Mach

CVS gnumach-1-branch

$ cvs -d:pserver:anoncvs@cvs.gnu.org:/cvsroot/hurd \
    co -r gnumach-1-branch gnumach
$ mv gnumach gnumach-1-branch

Prepare:

$ ( cd gnumach-1-branch/ && autoreconf -vfi )

src/mig: GNU Mach Interface Generator

CVS HEAD

$ cvs -d:pserver:anoncvs@cvs.gnu.org:/cvsroot/hurd co mig

Prepare:

$ ( cd mig/ && autoreconf -vfi )

src/hurd: GNU Hurd

CVS HEAD

$ cvs -d:pserver:anoncvs@cvs.gnu.org:/cvsroot/hurd co hurd

src/glibc: GNU C Library
- CVS glibc-2_7-branch
```
$ cvs -d:pserver:anoncvs@sources.redhat.com:/cvs/glibc \
    co -r glibc-2_7-branch glibc
$ mv libc glibc-2_7-branch
```
  - Patches: http://lists.gnu.org/archive/html/bug-hurd/2007-11/msg00030.html
- Recent releases of the 2.7 series from ftp://ftp.gnu.org/gnu/glibc/ should also be fine, but need the same set of patches as the glibc-2_7-branch needs.

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 (e.g., the upcoming 4.3, which is not yet supported) 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.

Makefile

A Makefile has been written to automate the above steps. You will require an Internet connection and atleast 1.5 GiB of hard-disk space. Just run...

make

... to build the toolchain. To clean up, use...

make clean

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 branches or want to quickly get a new tool chain 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 4.0 to GCC 4.1.

Comment

Unfortunately the GNU Automake build system (which is used by GNU Mach's gnumach-1-branch) will overwrite installed files (header files in this case here), even if they didn't change. And because all packages' build systems are using dependency tracking, a lot of files will be rebuilt each time cross-gnu is re-run, even if the files themselves didn't change. Talk to tschwinge if you want to work on fixing that -- it is already clear what needs to be done, it just hasn't been done yet.

References

http://lists.gnu.org/archive/html/bug-hurd/2004-09/msg00030.html