darkenvy/raspberryos repository overview

https://github.com/darkenvy/RaspberryOS-Docker⁠

⁠How to compile Raspberry OS from the RaspiFoundation into a docker image

1. Download Raspberry OS
2. fdisk -l 2021-05-07-raspios-buster-armhf-lite.img
3. Take start position of the second partition, and multiply it by the sector size (512). 532480x512=272629760
4. sudo mount -o loop,offset=272629760,ro 2021-05-07-raspios-buster-armhf-lite.img /mnt
5. sudo tar -C /mnt -c . | docker import - raspberryos-img
6. sudo docker build --no-cache -t darkenvy/raspberryos:TAGNAME .
7. docker push darkenvy/raspberryos:TAGNAME
8. docker image rm raspberryos-img

⁠How to run ARM docker container on x86_64

The ability to run a ARM container on x64 is not determined by how the docker image is constructed, but instead of how the host-OS is set up. If the host-OS has the ARM header registered in /proc/sys/fs/binfmt_misc, then whenever the kernel comes across a ARM binary, it will search for qemu located at /usr/bin/qemu-arm-static.

If the kernel comes across a ARM binary when operating inside a docker container, then it will look for qemu-arm-static from /usr/bin/qemu-arm-static relative to the docker container. Therefore, each docker container must contain the qemu-arm-static binary.

⁠How to register the host-OS to utilize qemu (inside and outside of docker)

1. Verify binfmt_misc is mounted a. grep binfmt /proc/mounts b. cat /proc/sys/fs/binfmt_mist/status
2. Mount binfmt if needed. mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc a. Note: Modern linux distros will have binfmt already enabled.
3. Enable if needed. echo 1 > /proc/sys/fs/binfmt_misc/status
4. Register the arm header info to binfmt: sudo sh -c "echo ':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:' > /proc/sys/fs/binfmt_misc/register"
5. Done! a. This container is built with qemu injected already. For other containers, all you have to do is volume mount pointing to qemu. docker run -it -v $(pwd)/qemu-arm-static:/usr/bin/qemu-arm-static darkenvy/raspberryos /bin/bash b. Note: If you dont have qemu-arm-static at /usr/bin/qemu-arm-static on the host, then the host will not execute ARM. This is fine and totally Optional.