Toolchain
Where to get a ARM toolchain?
You can find here more or less recent toolchains.
I suggest to create a file name /home/$USER/.cross_compile that contains:
export ARCH=arm export export CROSS_COMPILE=/path/to/your/toolchain
Each time, you need to build a software with this toolchain, you just have to source it.
If you are building Android, you can find it here: prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin/.