Building

Building

You only need a build of your own to change OOS or to try something that is not released yet. To install, the files of the latest release are enough: see Installation.

A build makes three files in boot/out/: oos-dev.img for a second card, oos-dev.oosupd, the signed update package, and DHO800_DHO900_OOS_Install.GEL for the USB stick.

Which computer

Host	How
macOS on Apple silicon	where OOS grew up
Linux on arm64	the same, natively
Linux on x86-64, an ordinary PC	the kernel and oos-hw cross-compiled in the build container, the Rust programs through rustup's target, busybox, wpa_supplicant and e2fsck from arm64 containers through QEMU

Windows: in a Linux virtual machine or WSL 2 with Docker, as on x86-64 Linux (untested).

Everything that needs a Linux tool chain runs in Docker. You need on the computer itself: Docker, Rust from rustup, Python 3, git and curl.

On Linux, also on x86-64

Debian or Ubuntu; other distributions need the same things. Run everything as yourself, not with sudo: under sudo, rustup's cargo is not found and the results belong to root.

1. Docker without sudo:

   sudo apt install docker.io git python3 curl
   sudo usermod -aG docker $USER

   Log out and in again. docker run --rm hello-world has to work without sudo.

2. Rust from rustup, not from apt. The packages of the distribution lack the target and rust-lld.

   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   rustup target add aarch64-unknown-linux-musl

3. x86-64 only: arm64 containers through QEMU. Again after every reboot:

   docker run --privileged --rm tonistiigi/binfmt --install arm64
   docker run --rm --platform linux/arm64 alpine:3.22 uname -m      # has to print aarch64

   You install no cross compiler yourself: the build container brings Ubuntu's gcc-aarch64-linux-gnu.

4. The source and the kernel archive. The archive is too large for git; it is a file of each release, and kernel/src/ is not in a clone:

   git clone https://github.com/deckerjulian/oos.git && cd oos
   mkdir -p kernel/src
   curl -fL -o kernel/src/linux-6.12.115-base.tar.xz \
     https://github.com/deckerjulian/oos/releases/latest/download/linux-6.12.115-base.tar.xz

5. Build:

   kernel/build-base.sh          # the kernel, only again when it changes
   boot/build-dev-image.sh       # the image, the update package and the USB file

   The first build takes longest: the build containers are made, and on x86-64 wpa_supplicant and e2fsck are compiled under QEMU. They are built once.

On macOS

Docker Desktop, running, and Rust from rustup with rustup target add aarch64-unknown-linux-musl. Then steps 4 and 5 above. The kernel takes about 5 minutes on an M-series Mac.

Signing

Update packages are signed. Without a key of your own the build uses the community key of the repository, which every OOS trusts; how to make your own: README, step 4. Only install packages from people you trust.

When it fails

The script says	What to do
do not run this with sudo	step 1, then run it as yourself
no cargo or missing Rust target	step 2
no rustup	Rust from the distribution: remove it, take rustup
Docker is not running / permission denied on the Docker socket	start Docker; on Linux, step 1 and log in again
Docker cannot run arm64 containers, or exec format error	step 3 (after a reboot again)
missing kernel/src/linux-6.12.115-base.tar.xz or wrong checksum	step 4; download it again
run kernel/build-base.sh first	the kernel comes before the image

If a step fails, the previous image stays in boot/out/: check the time of the file. For anything else, open an issue with the host, the distribution and the last lines of the output.

On GitHub

The workflow Image builds everything on an arm64 and on an x86-64 Linux runner for every release, and compares what the two put into the image: kernel, device tree, every file of the initramfs. The files of a run can be downloaded from its page.