How to install the Raspberry Pi cross compiler on my Linux host machine?

Question

I'm gonna try to write this as a tutorial for you so it becomes easy to follow.

NOTE: This tutorial only works for older raspbian images. For the newer Raspbian based on Debian Buster see the following how-to in this thread: https://stackoverflow.com/a/58559140/869402

Pre-requirements

Before you start you need to make sure the following is installed:

apt-get install git rsync cmake libc6-i386 lib32z1 lib32stdc++6

Let's cross compile a Pie!

Start with making a folder in your home directory called raspberrypi.

Go in to this folder and pull down the ENTIRE tools folder you mentioned above:

git clone git://github.com/raspberrypi/tools.git

You wanted to use the following of the 3 ones, gcc-linaro-arm-linux-gnueabihf-raspbian, if I did not read wrong.

Go into your home directory and add:

export PATH=$PATH:$HOME/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin

to the end of the file named ~/.bashrc

Now you can either log out and log back in (i.e. restart your terminal session), or run . ~/.bashrc in your terminal to pick up the PATH addition in your current terminal session.

Now, verify that you can access the compiler arm-linux-gnueabihf-gcc -v. You should get something like this:

Using built-in specs.
COLLECT_GCC=arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/home/tudhalyas/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/../libexec/gcc/arm-linux-gnueabihf/4.7.2/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: /cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.b
 uild/src/gcc-linaro-4.7-2012.08/configure --build=i686-build_pc-linux-gnu --host=i686-build_pc-
 linux-gnu --target=arm-linux-gnueabihf --prefix=/cbuild/slaves/oort61/crosstool-ng/builds/arm-l
 inux-gnueabihf-raspbian-linux/install --with-sysroot=/cbuild/slaves/oort61/crosstool-ng/builds/
 arm-linux-gnueabihf-raspbian-linux/install/arm-linux-gnueabihf/libc --enable-languages=c,c++,fo
 rtran --disable-multilib --with-arch=armv6 --with-tune=arm1176jz-s --with-fpu=vfp --with-float=
 hard --with-pkgversion='crosstool-NG linaro-1.13.1+bzr2458 - Linaro GCC 2012.08' --with-bugurl=
 https://bugs.launchpad.net/gcc-linaro --enable-__cxa_atexit --enable-libmudflap --enable-libgom
 p --enable-libssp --with-gmp=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-rasp
 bian-linux/.build/arm-linux-gnueabihf/build/static --with-mpfr=/cbuild/slaves/oort61/crosstool-
 ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static --with-mpc
 =/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-
 gnueabihf/build/static --with-ppl=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf
 -raspbian-linux/.build/arm-linux-gnueabihf/build/static --with-cloog=/cbuild/slaves/oort61/cros
 stool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static --wi
 th-libelf=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-linux/.build/a
 rm-linux-gnueabihf/build/static --with-host-libstdcxx='-L/cbuild/slaves/oort61/crosstool-ng/bui
 lds/arm-linux-gnueabihf-raspbian-linux/.build/arm-linux-gnueabihf/build/static/lib -lpwl' --ena
 ble-threads=posix --disable-libstdcxx-pch --enable-linker-build-id --enable-plugin --enable-gol
 d --with-local-prefix=/cbuild/slaves/oort61/crosstool-ng/builds/arm-linux-gnueabihf-raspbian-li
 nux/install/arm-linux-gnueabihf/libc --enable-c99 --enable-long-long
Thread model: posix
gcc version 4.7.2 20120731 (prerelease) (crosstool-NG linaro-1.13.1+bzr2458 - Linaro GCC 2012.08
 )

But hey! I did that and the libs still don't work!

We're not done yet! So far, we've only done the basics.

In your raspberrypi folder, make a folder called rootfs.

Now you need to copy the entire /liband /usr directory to this newly created folder. I usually bring the rpi image up and copy it via rsync:

rsync -rl --delete-after --safe-links [email protected]:/{lib,usr} $HOME/raspberrypi/rootfs

where 192.168.1.PI is replaced by the IP of your Raspberry Pi.

Now, we need to write a cmake config file. Open ~/home/raspberrypi/pi.cmake in your favorite editor and insert the following:

SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_VERSION 1)
SET(CMAKE_C_COMPILER $ENV{HOME}/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc)
SET(CMAKE_CXX_COMPILER $ENV{HOME}/raspberrypi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-g++)
SET(CMAKE_FIND_ROOT_PATH $ENV{HOME}/raspberrypi/rootfs)
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

Now you should be able to compile your cmake programs simply by adding this extra flag: -D CMAKE_TOOLCHAIN_FILE=$HOME/raspberrypi/pi.cmake.

Using a cmake hello world example:

git clone https://github.com/jameskbride/cmake-hello-world.git 
cd cmake-hello-world
mkdir build
cd build
cmake -D CMAKE_TOOLCHAIN_FILE=$HOME/raspberrypi/pi.cmake ../
make
scp CMakeHelloWorld [email protected]:/home/pi/
ssh [email protected] ./CMakeHelloWorld

Building for newer Raspbian Debian Buster images and ARMv6

The answer by @Stenyg only works for older Raspbian images. The recently released Raspbian based on Debian Buster requires an updated toolchain:

In Debian Buster the gcc compiler and glibc was updated to version 8.3. The toolchain in git://github.com/raspberrypi/tools.git is still based on the older gcc 6 version. This means that using git://github.com/raspberrypi/tools.git will lead to many compile errors.

This tutorial is based on @Stenyg answer. In addition to many other solutions in the internet, this tutorial also supports older Rasperry Pi (A, B, B+, Zero) based on the ARMv6 CPU. See also: GCC 8 Cross Compiler outputs ARMv7 executable instead of ARMv6

Set up the toolchain

There is no official git repository containing an updated toolchain (See https://github.com/raspberrypi/tools/issues/102).

I created a new github repository which includes building and precompiled toolchains for ARMv6 based on GCC8 and newer:

https://github.com/Pro/raspi-toolchain

As mentioned in the project's readme, these are the steps to get the toolchain. You can also build it yourself (see the README for further details).

1. Download the toolchain:

wget https://github.com/Pro/raspi-toolchain/releases/latest/download/raspi-toolchain.tar.gz

2. Extract it. Note: The toolchain has to be in /opt/cross-pi-gcc since it's not location independent.

sudo tar xfz raspi-toolchain.tar.gz --strip-components=1 -C /opt

3. You are done! The toolchain is now in /opt/cross-pi-gcc

4. Optional, add the toolchain to your path, by adding:

export PATH=$PATH:/opt/cross-pi-gcc/bin

to the end of the file named ~/.bashrc

Now you can either log out and log back in (i.e. restart your terminal session), or run . ~/.bashrc in your terminal to pick up the PATH addition in your current terminal session.

Get the libraries from the Raspberry PI

To cross-compile for your own Raspberry Pi, which may have some custom libraries installed, you need to get these libraries onto your host.

Create a folder $HOME/raspberrypi. In your raspberrypi folder, make a folder called rootfs.

Now you need to copy the entire /liband /usr directory to this newly created folder. I usually bring the rpi image up and copy it via rsync:

rsync -vR --progress -rl --delete-after --safe-links [email protected]:/{lib,usr,opt/vc/lib} $HOME/raspberrypi/rootfs

where 192.168.1.PI is replaced by the IP of your Raspberry Pi.

Use CMake to compile your project

To tell CMake to take your own toolchain, you need to have a toolchain file which initializes the compiler settings.

Get this toolchain file from here: https://github.com/Pro/raspi-toolchain/blob/master/Toolchain-rpi.cmake

Now you should be able to compile your cmake programs simply by adding this extra flag: -D CMAKE_TOOLCHAIN_FILE=$HOME/raspberrypi/pi.cmake and setting the correct environment variables:

export RASPBIAN_ROOTFS=$HOME/raspberry/rootfs
export PATH=/opt/cross-pi-gcc/bin:$PATH
export RASPBERRY_VERSION=1
cmake -DCMAKE_TOOLCHAIN_FILE=$HOME/raspberry/Toolchain-rpi.cmake ..

An example hello world is shown here: https://github.com/Pro/raspi-toolchain/blob/master/build_hello_world.sh

I couldn't get the compiler (x64 version) to use the sysroot until I added SET(CMAKE_SYSROOT $ENV{HOME}/raspberrypi/rootfs) to pi.cmake.

You may use clang as well. It used to be faster than GCC, and now it is quite a stable thing. It is much easier to build clang from sources (you can really drink cup of coffee during build process).

In short:

1. Get clang binaries (sudo apt-get install clang).. or download and build (read instructions here)
2. Mount your raspberry rootfs (it may be the real rootfs mounted via sshfs, or an image).

3. Compile your code:

   path/to/clang --target=arm-linux-gnueabihf --sysroot=/some/path/arm-linux-gnueabihf/sysroot my-happy-program.c -fuse-ld=lld
   

Optionally you may use legacy arm-linux-gnueabihf binutils. Then you may remove "-fuse-ld=lld" flag at the end.

Below is my cmake toolchain file.

toolchain.cmake

set(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

# Custom toolchain-specific definitions for your project
set(PLATFORM_ARM "1")
set(PLATFORM_COMPILE_DEFS "COMPILE_GLES")

# There we go!
# Below, we specify toolchain itself!

set(TARGET_TRIPLE arm-linux-gnueabihf)

# Specify your target rootfs mount point on your compiler host machine
set(TARGET_ROOTFS /Volumes/rootfs-${TARGET_TRIPLE})

# Specify clang paths
set(LLVM_DIR /Users/stepan/projects/shared/toolchains/llvm-7.0.darwin-release-x86_64/install)
set(CLANG ${LLVM_DIR}/bin/clang)
set(CLANGXX ${LLVM_DIR}/bin/clang++)

# Specify compiler (which is clang)
set(CMAKE_C_COMPILER   ${CLANG})
set(CMAKE_CXX_COMPILER ${CLANGXX})

# Specify binutils

set (CMAKE_AR      "${LLVM_DIR}/bin/llvm-ar" CACHE FILEPATH "Archiver")
set (CMAKE_LINKER  "${LLVM_DIR}/bin/llvm-ld" CACHE FILEPATH "Linker")
set (CMAKE_NM      "${LLVM_DIR}/bin/llvm-nm" CACHE FILEPATH "NM")
set (CMAKE_OBJDUMP "${LLVM_DIR}/bin/llvm-objdump" CACHE FILEPATH "Objdump")
set (CMAKE_RANLIB  "${LLVM_DIR}/bin/llvm-ranlib" CACHE FILEPATH "ranlib")

# You may use legacy binutils though.
#set(BINUTILS /usr/local/Cellar/arm-linux-gnueabihf-binutils/2.31.1)
#set (CMAKE_AR      "${BINUTILS}/bin/${TARGET_TRIPLE}-ar" CACHE FILEPATH "Archiver")
#set (CMAKE_LINKER  "${BINUTILS}/bin/${TARGET_TRIPLE}-ld" CACHE FILEPATH "Linker")
#set (CMAKE_NM      "${BINUTILS}/bin/${TARGET_TRIPLE}-nm" CACHE FILEPATH "NM")
#set (CMAKE_OBJDUMP "${BINUTILS}/bin/${TARGET_TRIPLE}-objdump" CACHE FILEPATH "Objdump")
#set (CMAKE_RANLIB  "${BINUTILS}/bin/${TARGET_TRIPLE}-ranlib" CACHE FILEPATH "ranlib")

# Specify sysroot (almost same as rootfs)
set(CMAKE_SYSROOT ${TARGET_ROOTFS})
set(CMAKE_FIND_ROOT_PATH ${TARGET_ROOTFS})

# Specify lookup methods for cmake
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

# Sometimes you also need this:
# set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

# Specify raspberry triple
set(CROSS_FLAGS "--target=${TARGET_TRIPLE}")

# Specify other raspberry related flags
set(RASP_FLAGS "-D__STDC_CONSTANT_MACROS -D__STDC_LIMIT_MACROS")

# Gather and distribute flags specified at prev steps.
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${CROSS_FLAGS} ${RASP_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CROSS_FLAGS} ${RASP_FLAGS}")

# Use clang linker. Why?
# Well, you may install custom arm-linux-gnueabihf binutils,
# but then, you also need to recompile clang, with customized triple;
# otherwise clang will try to use host 'ld' for linking,
# so... use clang linker.
set(CMAKE_EXE_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS} -fuse-ld=lld)