Bazel cross-compilation toolchains

Bazel build system supports integration with custom C/C++ toolchains. This project defines toolchains for x86_64 (64 bit), ARMv7-A (32 bit), and ARMv8-A (64 bit) processors based on the standard Linux crosstool packages, as well as for Windows x86_64 and ARM64 using Visual Studio.

The steps below describe how to setup cross-compilation for projects at github.com/google-coral/.

Step 1: Install required crosstool packages

For dpkg-based Linux systems (e.g. Debian, Ubuntu)

dpkg --add-architecture armhf
dpkg --add-architecture arm64

apt-get update && apt-get install -y build-essential crossbuild-essential-armhf crossbuild-essential-arm64

For Windows, install Visual Studio 2017 or newer.

Step 2: Update WORKSPACE file

You need to know the exact git commit of this repo to use:

COMMIT=$(git ls-remote https://github.com/google-coral/crosstool master | awk '{print $1}')

and corresponding SHA-256 hash:

SHA256=$(curl -L "https://github.com/google-coral/crosstool/archive/${COMMIT}.tar.gz" | sha256sum | awk '{print $1}')

Add the following piece of code to your WORKSPACE file while replacing ${COMMIT} and ${SHA256} values:

http_archive(
    name = "coral_crosstool",
    sha256 = "${SHA256}",
    strip_prefix = "crosstool-${COMMIT}",
    urls = [
        "https://github.com/google-coral/crosstool/archive/${COMMIT}.tar.gz",
    ],
)

load("@coral_crosstool//:configure.bzl", "cc_crosstool")
cc_crosstool(name = "crosstool")

Step 3: Add additional command line arguments to bazel build command

To compile for regular x86_64:

bazel build --crosstool_top=@crosstool//:toolchains --compiler=gcc --cpu=k8 <OPTIONS>

To compile for ARMv7-A (e.g. Raspberry Pi 3 or 4):

bazel build --crosstool_top=@crosstool//:toolchains --compiler=gcc --cpu=armv7a <OPTIONS>

To compile for ARMv8-A (e.g. Coral Dev Board):

bazel build --crosstool_top=@crosstool//:toolchains --compiler=gcc --cpu=aarch64 <OPTIONS>

To compile for Windows x86_64:

bazel build --crosstool_top=@crosstool//:toolchains --compiler=msvc-cl-x64

To compile for Windows ARM64:

bazel build --crosstool_top=@crosstool//:toolchains --compiler=msvc-cl-arm64 --host_crosstool_top=@crosstool//:toolchains --host_compiler=msvc-cl-x64