Bookworm armhf cross compile docker

Debian provides cross toolchains within their distribution for different architectures.

For best portability we recommend using a container like docker to run a Debian 12 rootfs for the toolchain. This will allow a consistent toolchain to run from almost any Linux system that can run Docker. Keep in mind that while docker does run under OSX and Windows, these are run under a case insensitive filesystem which will cause problems with complex builds like the Linux kernel so a Linux host is still recommended.

• Ubuntu/Debian:

sudo apt-get install docker -y

• Fedora

sudo dnf install docker -y

# Add your user to the docker group.  You may need to logout/log back in.
sudo usermod -aG docker $USER

Make sure you can run docker's hello world image as your user to verify it is working:

docker run hello-world

Now create a file Dockerfile:

sudo mkdir -p /opt/docker-toolchain/docker-debian-bookworm-armhf

In "/opt/docker-toolchain/docker-debian-bookworm-armhf/Dockerfile":

# syntax = docker/dockerfile:1.2

FROM debian:bookworm

RUN dpkg --add-architecture armhf

RUN apt-get update && apt-get install -y \
    autogen \
    automake \
    bash \
    bc \
    bison \
    build-essential \
    bzip2 \
    ca-certificates \
    ccache \
    chrpath \
    cpio \
    curl \
    diffstat \
    fakeroot \
    file \
    flex \
    gawk \
    gcc-arm-linux-gnueabihf \
    git \
    gzip \
    kmod \
    libgpiod-dev:armhf \
    libncursesw5-dev \
    libssl-dev \
    libtool \
    libyaml-dev \
    locales \
    lz4 \
    lzop \
    make \
    multistrap \
    ncurses-dev \
    pkg-config \
    python3 \
    python3-cbor \
    python3-pexpect \
    python3-pip \
    qemu-user-static \
    rsync \
    runit \
    socat \
    srecord \
    swig \ 
    texinfo \
    u-boot-tools \
    zstd \
    unzip \
    vim \
    wget \
    xz-utils

# Provide a more friendly name
ENV debian_chroot debian_bookworm
RUN echo "PS1='\${debian_chroot}\\[\033[01;32m\\]@\\H\[\\033[00m\\]:\\[\\033[01;34m\\]\\w\\[\\033[00m\\]\\$ '" >> /etc/bash.bashrc

# Set up locales
RUN sed -i -e 's/# en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen && \
        echo 'LANG="en_US.UTF-8"'>/etc/default/locale && \
        dpkg-reconfigure --frontend=noninteractive locales && \
        update-locale LANG=en_US.UTF-8
ENV LC_ALL en_US.UTF-8
ENV LANG en_US.UTF-8
ENV LANGUAGE en_US.UTF-8

# Needed for make dtbs_check
RUN pip3 install dtschema

Next make a shell script to enter into this docker container. In /usr/local/bin/docker-debian-bookworm:

#!/bin/bash -e

# Enters a docker running Debian 12 Bookworm
# Any arguments are run in the docker, or if no arguments it runs a shell

export TAG=debian-bookworm-armdev
SCRIPTPATH=$(readlink -f "$0")
DOCKERPATH=/opt/docker-toolchain/docker-debian-bookworm-armhf/

DOCKER_BUILDKIT=1 docker build --tag "$TAG" "$DOCKERPATH" --quiet

exec docker run --rm \
	-it \
	--volume "$(pwd)":/work \
	--user $(id -g):$(id -u) \
	-w /work \
	-e HOME=/tmp \
	"$TAG" \
	$@;

Make this executable, and call it:

sudo chmod a+x /usr/local/bin/docker-debian-bookworm

# dont run as root
docker-debian-bookworm

The first time this runs it will download a base Debian image, and run the above apt-get commands which may take a while depending on your internet connection and disk speed. After it has run once, it will stay cached and adds almost no overhead to run.

For example, to build a simple c project, create a ~/Desktop/hello-world/hello.c:

mkdir -p ~/Desktop/hello-world/

In ~/Desktop/hello-world/hello.c:

#include <stdio.h>

int main() {
    printf("Hello world!\n");
    return 0;
}

We can now use the docker in that directory to use Debian's cross compiler to create a binary that targets armhf: <console>