# Technical Guide

Build infrastructure, CI/CD configuration, and project structure for the Talos CM5 Builder.

## Building locally (ARM64 host required)

```bash
make checkouts patches   # Clone and patch upstream sources
make kernel              # Build RPi kernel
make overlay             # Build SBC overlay
make installer           # Build installer + disk image
```

## CI/CD (Gitea Actions)

Push a version tag to trigger an automated build:

```bash
git tag v1.12.3-k6.12.47-2
git push origin v1.12.3-k6.12.47-2
```

The pipeline runs on the ARM64 self-hosted runner and:
1. Builds the kernel, overlay, and installer
2. Attaches SBOM attestation (cosign + syft)
3. Pushes the installer image to Docker Hub
4. Creates a Gitea release with the raw disk image

### Upstream update checks

A weekly scheduled workflow checks for new Talos and RPi kernel releases and creates Gitea issues when updates are available.

## CI Secrets

| Secret | Description |
|--------|-------------|
| `REGISTRY_USERNAME` | Docker Hub username (org-level) |
| `REGISTRY_PASSWORD` | Docker Hub access token (org-level) |

## Runner Setup (ASUS GX10 — Linux arm64)

Builds run **natively on arm64** — no QEMU/binfmt emulation. The runner executes
jobs in **host mode** (directly on the Linux host, not in a container), so the
host provides the toolchain.

The build host needs:
- Docker Engine + the Buildx plugin (arm64 native)
- `make`, `git`, `curl`, `tar` (e.g. `apt-get install -y make git curl tar`)
- Sufficient disk space for kernel builds (~20GB)

`crane` and `jq` are fetched automatically by the workflows (static arm64
binaries into `~/.local/bin`), so they don't need to be pre-installed.

```bash
# Download the act_runner for linux/arm64
curl -sL https://gitea.com/gitea/act_runner/releases/latest/download/act_runner-linux-arm64 -o act_runner
chmod +x act_runner

# Register — the `:host` label runs jobs directly on the host (no container)
./act_runner register \
  --instance https://git.openharbor.io \
  --token <runner-token> \
  --name gx10 \
  --labels arm64:host

# Run as service
./act_runner daemon
```

> The workflows use `runs-on: arm64`. The `arm64:host` label maps that to host
> execution; drop `:host` only if you switch to container-based jobs (which then
> need Docker-in-Docker for the privileged build steps).

## Project Structure

```
.gitea/workflows/
  build.yaml              # Build pipeline (tag push trigger)
  check-updates.yaml      # Upstream update checker (weekly cron)
Makefile                   # Build orchestration
config/
  config.txt.append        # CM5 overclock settings
  extensions.yaml          # System extensions list
scripts/
  check-upstream.sh        # Version comparison script
patches/
  siderolabs/
    pkgs/0001-*.patch      # RPi kernel patch
    talos/0001-*.patch     # Module list patch
    talos/0002-*.patch     # Skip NVRAM writes for GRUB on arm64
    talos/0003-*.patch     # Force GRUB bootloader on arm64
  talos-rpi5/
    sbc-raspberrypi5/      # Overlay patches (Go toolchain bump)
cosign.pub                 # Public key for verifying image attestations
```