CrossToolchains

Contents

  1. CrossToolchains
    1. Cross Toolchain documentation
    2. Status of cross-toolchains in the Debian archive
      1. In jessie (Debian 8)
      2. In unstable
      3. In experimental
    3. Status of cross-toolchains in Ubuntu
    4. Installation
      1. For jessie (Debian 8)
      2. For unstable
      3. Using a chroot of unstable
      4. For Wheezy
      5. For Squeeze
      6. Older
    5. Removal

Cross Toolchain documentation

About the tools (installing, building, status, design):

Using the tools:

Talks:

Pages of largely historical interest:

Status of cross-toolchains in the Debian archive

In jessie (Debian 8)

In unstable

Currently (June 2015), the gcc-5 cross-compiler packages are built 'standalone' (depending on *-cross arch:all packages), whilst the gcc-4.9 cross-compiler packages are built with multiarch dependencies (depending on *:hostarch packages).

In experimental

Status of cross-toolchains in Ubuntu

Current details are given on https://wiki.ubuntu.com/ToolChain#Cross_development_toolchain

If you have an Ubuntu system, cross-toolchains (i386 & amd64->armel) have been included since 10.10/Maverick. From 12.10/Quantal onwards there are crossbuild-essential-<arch> convenience packages to install cross toolchains, cross-pkgconfig and (multiarch) cross-libc. Armel then armhf were initially supported. Arm64, powerpc and ppc64el were added later.

All these toolchains search multiarch library and header paths by default so are suitable for multiarch crossbuilding.

Installation

For jessie (Debian 8)

Cross-toolchains for jessie are available, only cross-binutils and cross-gcc-dev (crosstoolchain builder package) are in the main archive. Other packages come from an external repository.

The toolchains install on amd64 and i386 machines, targeting the jessie release architectures:

Currently cpp, gcc, g++, gfortran, gobjc and gccgo are built. It's easy to build more languages so ask if you have a need.

These packages did not make it into Jessie so you need to install them from the Debian Cross-toolchains repository. Create /etc/apt/sources.list.d/crosstools.list containing: 

deb http://emdebian.org/tools/debian/ jessie main

You will need the archive key installed. 

curl http://emdebian.org/tools/debian/emdebian-toolchain-archive.key | sudo apt-key add -

The key fingerprint is: 084C 6C6F 3915 9EDB 6796 9AA8 7DE0 8967 1804 772E (you will need to install curl in a bare chroot)

crossbuild-essential-<arch> packages exist to aid in installing the correct cross-packages. For instance to install the armhf cross-toolchain, first enable the foreign architecture (and update), then install crossbuild-essential-armhf : 

sudo dpkg --add-architecture armhf
sudo apt-get update
sudo apt-get install crossbuild-essential-armhf

This will pull in the required packages to cross-build for the target architecture, namely libc6-dev:<arch>, gcc-<triplet>, g++-<triplet> and dpkg-cross. (Note that dpkg-cross was removed from jessie, but remains in the Debian Cross-toolchains repository).

Note that if you also have debian unstable enabled in your apt sources you are likely to hit dependency issues. Either disable it or add an apt-preference to prefer jessie: 

echo "APT::Default-Release \"jessie\";" > /etc/apt/apt.conf.d/20defaultrelease

For unstable

You must enable the appropriate (HOST) foreign architecture before installing the cross-compiler. 

dpkg --add-architecture armhf
apt-get update

It is recommended to install the cross environment like this as that pulls in all the necessary components: 

apt-get install crossbuild-essential-<arch>

i.e 

apt-get install crossbuild-essential-armhf

But you can install just the compiler with 

apt-get install gcc-arm-linux-gnueabihf

Note that gcc-arm-linux-gnueabihf is (like the native 'gcc') just a metapackage, which brings int he current version of the actual compiler gcc-4.9-arm-linux-gnueabihf (c.f. gcc-4.9)

g++-<triplet>, gfortran-<triplet>, gobjc-<triplet> and gccgo-<triplet> packages also exist.

Using a chroot of unstable

For any release older than Jessie, the simplest way is to create a chroot of unstable and install your toolchain & build the package there. This is particularly simple if you are simply building a kernel or a package with only libc build dependencies. 

$ sudo debootstrap sid sid
$ sudo chroot sid
# dpkg --add-architecture armhf
# apt-get update
# apt install gcc-arm-linux-gnueabihf

For Wheezy

Without a chroot, you are blocked. Emdebian.org did have 'unstable' packages which would work on wheezy but these need to be restored after a server compromise.

For Squeeze

Packaged cross-toolchains are available from emdebian.org. These use classic cross-compiler paths and pre-date multiarch so expect to be used with xapt and/or dpkg-cross supplying build-dependencies.

Older

Emdebian.org keeps some 2.95 vintage packages in case that's useful (people do still ask occaisionally!). Currently awaiting re-uploading.

Removal

This is currently the same on all suites.

You can just use whatever package tools you like to remove crossbuild-essential-<arch> or gcc-<triplet> in the usual way. However if you have installed cross-build-deps then there may well be a lot of foreign-architecture -dev packages installed.

If you want to remove all foreign-arch packages and the corresponding foreign architecture entirely then you need to remove all the :arch packages before you run dpkg --remove-architecture arch. This one-liner should work: 

sudo apt-get remove `dpkg-query -f'${Package}:${Architecture}\n' -W '*:arch'`

where 'arch' is the foreign architecture you want to remove.