punktfunk/packaging/arch/README.md

punktfunk on Arch Linux / SteamOS

Packaging for punktfunk on Arch and Arch-derived immutable distros (SteamOS 3, etc.). The PKGBUILD is a split package producing punktfunk-host (the gaming-rig host) and punktfunk-client (the GTK4 couch/Deck client) — mirrors the rpm subpackages (packaging/rpm/punktfunk.spec) and the deb build scripts. On a Steam Deck you want punktfunk-client (it's what the Decky plugin launches); on a gaming rig, punktfunk-host.

A third member, punktfunk-web (the browser management console — pairing + status), is opt-in: build it by setting PF_WITH_WEB=1, which requires bun at build time (bun-bin from the AUR if it isn't in your repos; the console then runs on plain nodejs). A default makepkg builds only host+client with no JS tooling — mirroring the RPM spec's %bcond_with web.

⚠️ Host encode is NVENC-only today. crates/punktfunk-host/src/encode/linux.rs implements hevc_nvenc/av1_nvenc/h264_nvenc + a CUDA zero-copy path — there is no VAAPI encoder. So punktfunk-host works on Arch + NVIDIA (incl. bazzite-deck-nvidia); an AMD Deck-as-host can't encode until a hevc_vaapi backend is added (a code change, not packaging). The client is unaffected — punktfunk-client decodes via VAAPI on AMD/Intel (the Deck) with a software fallback, so streaming to a Deck works today.

Arch Linux (mutable)

cd packaging/arch
# Build the working tree (CI / dev) — no git fetch:
PF_SRCDIR="$(git rev-parse --show-toplevel)" makepkg -f --holdver
# …or build the tagged release the AUR way:
makepkg -si
# …add the web console too (needs bun / bun-bin):
PF_WITH_WEB=1 PF_SRCDIR="$(git rev-parse --show-toplevel)" makepkg -f --holdver

Then the standard first-run (printed by the install scriptlet):

sudo usermod -aG input "$USER"          # virtual gamepads; re-login after
mkdir -p ~/.config/punktfunk
cp /usr/share/punktfunk/host.env.bazzite ~/.config/punktfunk/host.env   # gamescope backend
systemctl --user enable --now punktfunk-host
# Web console (if you installed the punktfunk-web package): enable it + read the login password.
systemctl --user enable --now punktfunk-web
journalctl --user -u punktfunk-web-init | sed -n 's/.*password generated: //p'   # open http://<host-ip>:3000

NVENC/EGL come from the NVIDIA driver: sudo pacman -S --needed nvidia-utils. Arch's stock ffmpeg already has NVENC built in — no RPM-Fusion-style swap needed (unlike Fedora).

Runtime dependency map (Fedora/Debian → Arch)

Need	Arch package
FFmpeg + NVENC	ffmpeg (NVENC built in)
PipeWire + Pulse + session mgr	pipewire pipewire-pulse wireplumber
Opus / input injection	opus libei
GL/EGL + gbm + xkb + wayland	libglvnd mesa libxkbcommon wayland
NVIDIA driver (NVENC/EGL/CUDA)	nvidia-utils (optdepend — never a hard dep)
Compositor backends	gamescope (≥3.16.22) / kwin / mutter / sway (optdepends)

SteamOS 3 (immutable) — use a systemd-sysext

SteamOS has a read-only /usr on A/B partitions, and every OS update reimages the rootfs — so steamos-readonly disable + pacman (and flatpak/distrobox) are fragile or unusable for a host that needs /dev/uinput, /dev/uhid, the host PipeWire socket, the GPU render node, and the right to spawn a compositor. The update-survivable, SteamOS-blessed mechanism is a systemd-sysext: an overlay image merged read-only over /usr at boot, living in the writable /var/lib/extensions/ (so it persists across A/B updates, no readonly-disable).

Build the package, then wrap its /usr payload into a sysext image:

# 1. build the pacman package (needs an Arch environment / container)
cd packaging/arch && PF_SRCDIR="$(git rev-parse --show-toplevel)" makepkg -f --holdver
# 2. turn it into a sysext .raw (extracts the package's /usr into an image + extension-release)
bash build-sysext.sh punktfunk-host-*.pkg.tar.zst
# 3. on the SteamOS box:
sudo cp punktfunk-host.raw /var/lib/extensions/
sudo systemctl enable --now systemd-sysext      # merges it; survives OS updates
systemctl --user enable --now punktfunk-host     # the user unit is now under /usr/lib

The udev rule, sysctl, and systemd user unit all live under /usr/lib, so the merged sysext exposes them. systemd-sysext refresh re-merges after a reboot.

Steam Deck — the client (what the Decky plugin launches)

To stream to a Deck, you install punktfunk-client there — same sysext mechanism, but wrapping the client package instead. The split makepkg produces both .pkg.tar.zst files; on the Deck use the client one:

cd packaging/arch && PF_SRCDIR="$(git rev-parse --show-toplevel)" makepkg -f --holdver
bash build-sysext.sh punktfunk-client-*.pkg.tar.zst        # → punktfunk-client.raw
# on the Deck:
sudo cp punktfunk-client.raw /var/lib/extensions/
sudo systemctl enable --now systemd-sysext
sudo pacman -S --needed libva-mesa-driver                  # VAAPI hw decode on the Deck's AMD APU

Now punktfunk-client is on PATH, so the Decky plugin finds and launches it (punktfunk-client --connect host:port) — gamescope composites its video like a game. The client needs no /dev/uinput or compositor-spawning rights (it captures input and decodes), so it's a much lighter sysext than the host.

Files

• PKGBUILD — split package: punktfunk-host + punktfunk-client (builds the working tree via PF_SRCDIR, or a git tag for AUR).
• punktfunk-host.install / punktfunk-client.install — pacman scriptlets (udev reload + sysctl + first-run hint), mirror the RPM %post / deb postinst.
• build-sysext.sh — wraps either built .pkg.tar.zst into a systemd-sysext .raw for SteamOS (derives the name from the package, so it works for host or client).