enricobuehler
2f9e61d191
Now that the per-capture worker subprocess makes an NVENC EGL/CUDA driver fault survivable (design/zerocopy-worker-isolation.md), the reason the NVENC zero-copy path stayed opt-in is gone. zerocopy::enabled() now defaults ON for both GPU backends (was ON VAAPI / OFF NVENC). Fallbacks are intact: VAAPI's one-shot CPU auto-downgrade (VAAPI-gated, never trips for NVENC) and NVENC's per-capture fallback + worker-death latch. Reframe the shipped host.env examples and setup guides to rely on the default rather than force PUNKTFUNK_ZEROCOPY=1 (an explicit =1 skips the VAAPI auto-downgrade). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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title, description
| title | description |
|---|---|
| KDE Plasma (KWin) | Configure a punktfunk host for KDE — host.env, quirks, and a headless KWin session. |
Configure a punktfunk host on KDE Plasma. The host uses KDE's KWin compositor to create a per-client virtual display, captured zero-copy on NVIDIA. This page assumes the package is already installed — see Ubuntu, Fedora, Arch, or the Bazzite appliance.
New here? Read Security & Safe Use first — a streaming host is remote control of the machine, so keep it on a trusted LAN or VPN and require pairing.
host.env
A KDE starter ~/.config/punktfunk/host.env:
WAYLAND_DISPLAY=wayland-0
XDG_CURRENT_DESKTOP=KDE
PUNKTFUNK_COMPOSITOR=kwin
PUNKTFUNK_VIDEO_SOURCE=virtual
# GPU zero-copy (dmabuf → CUDA → NVENC) is ON by default; auto-falls back to CPU. Set =0 to force CPU.
PUNKTFUNK_INPUT_BACKEND=libei
The host auto-detects the running compositor on every connect, so most of this is optional — the values above are just what it resolves to on a KWin session. See the Configuration reference for every option.
Use a Wayland session
KDE must run on Wayland, not X11 — pick the Wayland session from the picker on the login screen. The virtual-display path is Wayland-only and will not come up under X11.
KWin must be 6.5.6 or newer (virtual outputs land there). Check with:
kwin_wayland --version
Streaming the interactive desktop
To stream a logged-in Plasma desktop (rather than a headless session, below), KWin has to hand the
host its restricted screencast protocol. The host package ships an io.unom.Punktfunk.Host.desktop
file whose X-KDE-Wayland-Interfaces grants exactly that on a normal interactive session
(least-privilege, the same mechanism krfb/krdp use). After a fresh install, log out and back into
the Desktop session once so KWin re-reads the grant.
A normal KDE login still lacks the RemoteDesktop grant that input injection needs — without it the host pops an "Allow remote control?" dialog no headless box can answer. Fedora and Bazzite ship a one-shot helper that seeds it (run once as the streaming user, no root):
bash /usr/share/punktfunk/bazzite/kde-desktop-setup.sh # Fedora / Bazzite
The .deb and Arch packages don't include that wrapper. Seed the grant by hand instead — copy the
shipped kde-authorized file into the portal store (the share dir is /usr/share/punktfunk-host on
Debian/Ubuntu, /usr/share/punktfunk on Arch), then log out and back in:
mkdir -p ~/.local/share/flatpak/db
cp /usr/share/punktfunk*/headless/kde-authorized ~/.local/share/flatpak/db/kde-authorized
A login-less appliance skips all of this — its headless session (below) needs none of these grants.
Start the host
With host.env in place, start the host from inside your Plasma session:
systemctl --user enable --now punktfunk-host
journalctl --user -u punktfunk-host -f # watch it come up and print its identity fingerprint
Then bring up The Web Console to arm pairing and connect a client. To start at boot — including fully headless — see the headless session below or Running as a Service.
Persistent per-client scaling
KWin round-trips per-client display scale: it names each session's virtual output per client, so a scale you set for one client (150 %, 125 %, …) is reapplied on that client's next connect. See Virtual displays.
Headless session
For a login-less appliance — a box that streams at boot with no graphical login — the host brings up a
dedicated headless KWin session rather than relying on an interactive one. It runs its own
kwin --virtual session (shipped as the punktfunk-kde-session.service unit) with permission checks
relaxed, so it needs none of the interactive grants above.
mkdir -p ~/.config/punktfunk
cp /usr/share/punktfunk/host.env.kde ~/.config/punktfunk/host.env # Debian/Ubuntu: /usr/share/punktfunk-host/host.env.kde
systemctl --user daemon-reload
systemctl --user enable --now punktfunk-kde-session punktfunk-host
sudo loginctl enable-linger "$USER"
The session unit brings up headless KWin; the host unit follows it and starts listening. See Running as a Service for the full headless setup.
Troubleshooting
- KWin too old: virtual outputs need KWin ≥ 6.5.6. Check with
kwin_wayland --version. - Black screen / no picture: confirm you're on a Wayland session (not X11) and the NVIDIA GL userspace is installed. More in Troubleshooting.
To bring the console up and pair, see The Web Console.