gahag / freebsd-cross-build

(Cross) Compile FreeBSD binaries on Linux

freebsd-cross-build

This creates a container that can be used to cross-compile FreeBSD binaries natively on Linux.

To build:

docker build -t freebsd-cross .

To run:

docker run --rm -it freebsd-cross bash

There is /freebsd/bin on the path. It has all of the build tools (e.g. x86_64-pc-freebsd12-gcc)

It is likely you would add a -v switch to the run (to put your code on a mount).

Rust Image

There is a second Dockerfile that can be used to cross-compile FreeBSD Rust binaries.

To build:

docker build -f Dockerfile.rust -t freebsd-cross-rust .

I wrote a blog post about creating this on my blog.

Example of its use on a Rust project:

In your project add a .cargo/config file for the x86_64-unknown-freebsd target. This tells cargo what tool to use as the linker.

[target.x86_64-unknown-freebsd]
linker = "x86_64-pc-freebsd12-gcc"

Then, use the following script:

#!/bin/sh

# This should be executed from the project root.

set -e

mkdir -p target

project=${PWD##*/} # Use the directory's name as the name of the project.
container="$project-freebsd-build"

# Use the container itself as the cache layer for the registry.
# This implies we won't create a new container for every build,
# but just start the same container.
if ! docker ps -a --format '{{.Names}}' | grep -Eq "^${container}\$"; then
	docker create \
	       --name "$container" \
	       -i -a STDIN -a STDOUT -a STDERR \
	       -v "$(pwd)":/rust/project:ro \
	       freebsd-cross-rust
fi

echo "cargo build --release --target x86_64-unknown-freebsd --target-dir /rust/target" \
	| docker start -i "$container"

docker cp "$container":/rust/target/x86_64-unknown-freebsd/ target/x86_64-unknown-freebsd/

The script sets up a container for building your project. The build artefacts are cached within the container, and the build is executed by just piping the build command into the container. As with the build command, other commands can be piped into the container:

• To install possible dependencies, like libfl-dev and libsqlite3-dev.
• To install other toolchains, like nightly.

Please note that when installing a new toolchain, the x86_64-unknown-freebsd target must be added for such toolchain.