(Crosstoolchain documentation is now collected and indexed on CrossToolchains)
Building a Cross Compiler
Very few people need to build a cross-toolchain. It is a complicated business and unless you are doing something really quite obscure you should just install a suitable apt-able toolchain. Installation info is on CrossToolchains.
We'll say that again: MOST PEOPLE SHOULDN'T BE BUILDING THEIR OWN CROSS-TOOLCHAIN - THEY SHOULD JUST INSTALL A PRE-BUILT ONE LIKE ANY OTHER PACKAGE.
But there are reasons why you might need to do this.
I really do want to build a cross compiler
Pick the most relevant heading from the list below.
I want a combination of BUILD x HOST not in Debian on unstable
HOST is a debian release architecture
If HOST is a debian release architecture then this is fairly straightforward:
- Install the cross-gcc-dev binary package
apt-get install cross-gcc-dev
This is available from jessie (Debian 8) onwards
Generate a cross-gcc-<gccver>-<arch> source package
TARGET_LIST=<hostarch> cross-gcc-gensource <gccver>
Fill in your own <hostarch> and <gccver> above. (e.g. TARGET_LIST="armel armhf" cross-gcc-gensource 4.9) In jessie only '4.9' is supported as a gcc version.
This will generate (in a directory called cross-gcc-packages-<buildarch>) a cross-gcc-<gccver>-<arch> source package for each arch in the TARGET_LIST.
- Build it
cd cross-gcc-<gccver>-<arch> sbuild -d jessie
You will need sbuild 0.64.3 or later installed, and a suitable chroot or build env for the target suite.
A more manual build, probably best done in a chroot, could be
cd packages/cross-gcc-4.9-<hostarch> dpkg --add-architecture <hostarch> apt-get update [install build-deps] dpkg-buildpackage
(This essentially automates the procedure described on MultiarchCrossToolchainBuild).
HOST is not a debian release architecture
If HOST is not a debian release architecture (debian-ports architecture or a new arch), then it may be much harder because you need to do a full kernel/libc/gcc bootstrap. cross-toolchain-base packages exist in Ubuntu for this for some architectures, but the procedure is broken in Debian at the time of writing (May 2015) so you'll need to fiddle with patches. We do hope to have this working soon.
I want the very latest arm support
Linaro's cross-toolchains (tarball install, sadly) are very up to date with patches and support, and may well be useful. But they are supplied as a binary tarball, not as debian packages.
I want toolchain packages for wheezy
The packages on emdebian.org aimed at wheezy have been uninstallable for a long time. Install buildcross from experimental and use that to build your own.
<some instructions here would be helpful>