Dockerfile to cross-compile kernel modules for Raspberry Pi

Easier and faster than a VM. I was specifically interested on cross-compiling reloadable kernel modules.

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Set-up

1. Clone repository.

git clone https://github.com/danx12/rpi-docker-cc
cd rpi-docker-cc

2. Obtain the build configuration from the Raspberry pi.

# (On the raspberry pi)
sudo modprobe configs

# (On your laptop)
sudo scp pi@ipaddress:/proc/config.gz ./

3. Obtain the kernel hash.

# (On the raspberry pi)
FIRMWARE_HASH=$(zgrep "* firmware as of" /usr/share/doc/raspberrypi-bootloader/changelog.Debian.gz | head -1 | awk '{ print $5 }')
KERNEL_HASH=$(wget https://raw.github.com/raspberrypi/firmware/$FIRMWARE_HASH/extra/git_hash -O -)
echo $KERNEL_HASH

Copy the outputed hash and run:

# (On your laptop)
echo <PASTE KERNEL HASH HERE> >> hash.txt

4. Build Docker image

docker build -t rpi-cc .

The building process will take a while, the raspberry pi kernel will be downloaded, primed and compiled.

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Usage

Change to directory containing your source files and Makefile. To make the kernel module run.

docker run --rm -it -v $PWD:/src rpi-cc

It is possible to also run make clean

docker run --rm -it -v $PWD:/src rpi-cc make clean

Or bash to do some other stuff in the container.

docker run --rm -it -v $PWD:/src rpi-cc bash