Good news, the gcc-2.95 source package will build cross-compilers
out of the box.

It should be able to build cross-compilers for any debian
architecture as a target, although you may find it difficult to
fulfill the dependencies for every target.

- Install the following packages (additional Build-Depends:) before
  continuing:

    dpkg-cross
    binutils-multiarch
    binutils-${target}

  binutils-${target} is only in sid, and only for powerpc, m68k,
  arm, and avr.  If you are building for some other target, you'll
  need to find a cross binutils some other way, i.e., by fixing
  the binutils package.

- Download (by hand, probably) the binary packages
  libc6_*_${target}.deb and libc6-dev_*_${target}.deb.

- dpkg-cross is a cool utility that mangles library and lib-dev
  packages to be cross development packages.  The install path
  is changed (e.g.) from /usr/lib to /usr/${target}-linux/lib,
  so you don't affect the native installation.  Run the command

    dpkg-cross -a ${target} -b libc_*_${target}.deb
    dpkg-cross -a ${target} -b libc-dev_*_${target}.deb

  This will create libc-${target}-cross_*_all.deb and
  libc-dev-${target}-cross_*_all.deb.  (Note that they are now
  architecture independent.)  Look at the packge contents,
  in order to marvel at the coolness of dpkg-cross and/or to
  verify that it worked:

    dpkg-deb -C libc-${target}-cross_*_all.deb

  Of course, you can do this for other development packages that
  you want to install later.

- Install the cross-libc packages created in the last step.  The
  gcc build process needs these to build libgcc2 and libg++.

- Create the directory /usr/lib/gcc-lib/${target}-linux/2.95.4.
  This is to overcome a buglet in the current build.  Fix the version
  number if it has changed.

- Edit the file gcc-2.95-*/debian/rules.defs where it defines
  TARGETS.  Change this to 'TARGETS = ${target}'.

- In order to speed up the build process, disable the regression
  tests.  Search for 'with_check := disabled by hand' in
  gcc-2.95-*/debian/rules.defs and uncomment it.

- In order to speed up the build process, disable building of the
  Pascal compiler if you don't need it.  Search for 'with_pascal
  := disabled by hand' in gcc-2.95-*/debian/rules.defs and uncomment
  it.

  The same thing can be done for the CHILL, Fortran and Java compilers.

- Build using 'dpkg-buildpackage -rfakeroot'.  This will take a _long_
  time, as it builds a bootstrap native compiler first, and also
  builds the native packages.


Please send any comments/corrections to this document to
David Schleef <ds@schleef.org>.