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Building a Cross Compiler
This document will help you build Debian packages of a cross-compilation toolchain. It is based on [http://psas.pdx.edu/DebianCrossCompilerHowto a HOWTO] by Josh Triplett, with his kind permission.
Commands you need to run as root assume you have already set up sudo on your system.
We will be building a cross-compiler from the gcc-4.1 package. Specific version numbers for packages are listed as VERSION; substitute the version number of the latest package in unstable (or testing).
Build a cross-compilation toolchain
Create a working directory
mkdir -p ~/src/cross-toolchain cd ~/src/cross-toolchain
Some useful variables
These will be used in the commands in this document. Replace "arm" with the architecture for which you are building a cross-compiler.
export -n ARCH=arm # set and do not export to subshells
Get the source for binutils and GCC
apt-get source binutils gcc-4.1
Install Build-Depends
sudo apt-get build-dep binutils gcc-4.1
Note that gcc-4.1 may have build-dependencies that apt-get can't figure out; this is not a problem, just make sure you install all the ones that apt-get understands. Unfortunately, apt-get build-dep may give an error if such a situation arises; in this case, take the list of packages apt-get provided before giving an error, and install them using "sudo apt-get install pkg1 pkg2 pkg3 ...".
Install fakeroot
fakeroot allows you to build packages without being root.
sudo apt-get install fakeroot
Install dpkg-cross
dpkg-cross adds cross-compilation support to some of the basic Debian package tools. dpkg-cross can also convert packages designed for the target architecture into packages usable for cross-compilation to that architecture.
sudo apt-get install dpkg-cross
Build and install binutils
dpkg-source -x binutils_VERSION.dsc cd binutils-VERSION TARGET=$ARCH-linux-gnu fakeroot debian/rules binary-cross > ../binutils.build 2>&1 || echo 'Build error' cd .. sudo dpkg -i binutils-$ARCH-linux-gnu_VERSION_HOSTARCH.deb
Convert library packages
You will need cross-compilation packages for various libraries; dpkg-cross can convert native packages for the target architecture into packages usable for cross-compilation. Note that the mirror ftp.us.debian.org only has amd64 and i386 packages, so to build a cross-compilation toolchain for another architecture (e.g. arm), you will have to use a mirror other than ftp.us.debian.org.
wget http://ftp.XX.debian.org/debian/pool/main/g/glibc/libc6-dev_VERSION_$ARCH.deb wget http://ftp.XX.debian.org/debian/pool/main/g/glibc/libc6_VERSION_$ARCH.deb wget http://ftp.XX.debian.org/debian/pool/main/l/linux-kernel-headers/linux-kernel-headers_VERSION_$ARCH.deb dpkg-cross -a $ARCH -b l*.deb sudo dpkg -i l*$ARCH-cross*.deb
Build and install GCC
Now that you have all the necessary prerequisites, you can build a cross-compiling GCC.
dpkg-source -x gcc-VERSION.dsc cd gcc-VERSION export GCC_TARGET=$ARCH debian/rules control dpkg-buildpackage -us -uc -rfakeroot -b > ../gcc.build 2>&1 || echo 'Build error' cd .. sudo dpkg -i *-VERSION-$ARCH-linux-gnu*.deb *-$ARCH-cross_VERSION*.deb
Test the cross-compile environment
Test compilation
Create a file "hello.c", containing the following code:
#include <stdio.h> int main() { printf("Hello cross-compiling world!\n"); return 0; }
Compile it statically with the new cross-compiler.
$ARCH-linux-gnu-gcc -static hello.c -o hello
Check the binary's type with "file".
file hello
You should see something like:
hello: ELF 32-bit MSB executable, PowerPC or cisco 4500, version 1 (SYSV), for GNU/Linux 2.2.0, statically linked, not stripped
for the PowerPC architecture.
Install qemu
qemu is an emulator for various architectures. It supports both whole-system emulation as well as single-program emulation with system-call conversion.
sudo apt-get install qemu
Run the test program with qemu
To run the test program with qemu, just prefix it with "qemu-$ARCH" (assuming of course that your architecture is supported by qemu).
qemu-$ARCH ./hello
You should see:
Hello cross-compiling world!