README.arm.md

Building Julia on ARM

Julia has been compiled on several ARMv7 / Cortex A15 Samsung Chromebooks running Ubuntu Linux under Crouton. This is a work in progress - several tests are known to fail, and backtraces are not available.

In addition to the standard build-essentials toolchain the following libraries must be installed to build on ARM. On Debian/Ubuntu, use the following command:

sudo apt-get install libblas3gf liblapack3gf libfftw3-dev libgmp3-dev libmpfr-dev libblas-dev liblapack-dev cmake gcc-4.7 g++-4.7 gfortran libgfortran3

Please start from the standard build instructions, in particular the Linux notes.

Next, create a file in the julia top-level directory called Make.user with the following contents:

include $(JULIAHOME)/Make.arm

Then proceed to build as described in the primary README. Just typing make -j 4 at this stage should build julia.

Installing Crouton for Chromebooks

If you do not have an Ubuntu chroot running on your Chromebook using Crouton, you can do so by following these tutorials.

• Crouton Tutorial 1
• Crouton Tutorial 2

Known ARM issues

• This is the list of known issues on ARM: https://github.com/JuliaLang/julia/labels/arm

Building LLVM on ARM

• If you run in to issues building LLVM, see these notes: http:https://llvm.org/docs/HowToBuildOnARM.html

For the Raspberry Pi version 2 (RPi2)

Success in building Julia has been reported using the following procedure:

1. Follow the steps above to install the build-essentals and other packages required for ARM
2. Install FFTW and libedit using sudo apt-get install libfftw3-3 libedit-dev
3. Download the [LLVM 3.6.0 binaries for ARMv7a] (http:https://llvm.org/releases/3.6.0/clang+llvm-3.6.0-armv7a-linux-gnueabihf.tar.xz) and extract them in a local directory.
4. For each file in the extracted bin, include, and lib subdirectories, create symlinks from the corresponding directory under /usr/local.
5. Using the Make.arm configuration below, build Julia using make -j 2. (Limiting make to 2 simultaneous jobs will reduce the possibility of running out of memory/swap space during the build process.)

Note that the resulting Julia binary may fail various tests but will run code and provide the REPL.

Make.arm for RPi2:

override LLVM_ASSERTIONS=1
LLVM_FLAGS+="--with-cpu=cortex-a9 --with-float=hard --with-abi=aapcs-vfp --with-fpu=neon --enable-targets=arm --enable-optimized --enable-assertions"

override OPENBLAS_DYNAMIC_ARCH=0
override OPENBLAS_TARGET_ARCH=ARMV7
override USE_BLAS64=0

override USE_SYSTEM_LIBM=1
override USE_SYSTEM_FFTW=1
override USE_SYSTEM_GMP=1
override USE_SYSTEM_MPFR=1
override USE_SYSTEM_LAPACK=1

JCFLAGS += -fsigned-char

override USE_SYSTEM_LLVM=1
override USE_SYSTEM_BLAS=1