Punktfunk Docs

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 the GPU (NVIDIA, AMD and Intel alike). 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

The host auto-detects your KWin session on every connect — including a box that switches between the Plasma desktop and Steam Game Mode — so the starter ~/.config/punktfunk/host.env is one line:

# ~/.config/punktfunk/host.env  (keys are case-sensitive)
PUNKTFUNK_VIDEO_SOURCE=virtual
# GPU zero-copy capture→encode (dmabuf → CUDA/NVENC on NVIDIA, dmabuf → Vulkan Video or VAAPI on
# AMD/Intel) is ON by default; auto-falls back to CPU. Set PUNKTFUNK_ZEROCOPY=0 to force CPU.

Don't set PUNKTFUNK_COMPOSITOR, WAYLAND_DISPLAY, or XDG_CURRENT_DESKTOP here. Pinning the compositor turns auto-detection off — per connect and mid-stream — so a switch to Game Mode then kills the stream instead of being followed, and stale session values point the host at dead sockets. Forcing a backend is for CI and dedicated appliances (the headless session below ships a host.env.kde that pins on purpose).

If the box switches between the desktop and Game Mode, also enable lingering — the host is a user service, and without linger the logout moment of a session switch tears it (and PipeWire) down mid-stream:

sudo loginctl enable-linger "$USER"

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.

On a normal Plasma login KWin drives your real hardware, and any Plasma 6 release can create the virtual output — what it needs is the screencast grant below, not a particular version. The headless session further down is the exception: it runs kwin_wayland --virtual, and that backend only learned to create virtual outputs in KWin 6.5.6, so an appliance box needs 6.5.6 or newer. 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.

Input needs no extra setup. That same .desktop file also grants org_kde_kwin_fake_input, so the host injects keyboard, mouse and touch straight into KWin — no portal, and no "Allow remote control?" dialog for a headless box to answer, on every distro. All a fresh install needs is the log out and back in above, so KWin re-reads the grant.

The old RemoteDesktop-portal grant only matters now if you force the libei input backend (PUNKTFUNK_INPUT_BACKEND=libei) — that one injects through the RemoteDesktop portal, and on KDE it is also what a portal capture (PUNKTFUNK_VIDEO_SOURCE=portal) is anchored to, so the capture inherits the same grant. To seed it, Fedora and Bazzite ship a one-shot helper (run once as the streaming user, no root); the .deb and Arch packages don't include that wrapper, so copy the shipped kde-authorized file into the portal store by hand instead (the share dir is /usr/share/punktfunk-host on Ubuntu, /usr/share/punktfunk on Arch) and log out and back in:

bash /usr/share/punktfunk/bazzite/kde-desktop-setup.sh    # Fedora / Bazzite

mkdir -p ~/.local/share/flatpak/db                        # Ubuntu / Arch
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

This unit runs the secure native-only host; to serve stock Moonlight clients as well, see What the unit starts.

A desktop-login host should also follow your session's lifetime, or restarting Plasma leaves the host wired to a compositor that is gone — it keeps answering, and every session after that fails at capture. Add the drop-in from Restart the host with your desktop. Skip it on the headless appliance route below.

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   # 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 isn't handing over the screencast protocol: run punktfunk-host probe-compositor from inside the session. It exits 0 only when KWin is up and advertising the grant to the host, and prints the reason when it isn't — after a fresh install that is usually just the missing log out and back in. On the headless appliance session, also check kwin_wayland --version is ≥ 6.5.6. The other cause has nothing to do with the .desktop file: getcap /usr/bin/punktfunk-host must print nothing at all. A host binary carrying a Linux capability cannot be identified by KWin and is never offered the protocol, however correctly its grant is installed — see GPU scheduling priority.
"KWin virtual output failed: Could not find output" (the message arrives translated — a Brazilian session reads "Não foi possível encontrar saída"): KWin got the request and refused it, so the grant above is fine and only the output creation is not. Two shapes. Its backend can't create one — a nested KWin, or kwin_wayland --virtual below 6.5.6; a normal Plasma session on the DRM backend always can. Or, on KWin 6.6+, KWin created the output and then left it disabled. That reports identically, and it is new: 6.6 put a workspace()->findOutput() hop in front of the stream, so from 6.6 on the output must also be enabled and workspace-managed, where 6.5 and earlier streamed it either way. Check punktfunk-host list-monitors for a Virtual-punktfunk-* marked disabled, a stale entry in ~/.config/kwinoutputconfig.json, and journalctl --user -b -t kwin_wayland for "Applying output configuration failed!" — KWin logs that when it declines to enable one more output next to your current monitors, and keeps the old configuration instead. Streaming a real monitor (PUNKTFUNK_CAPTURE_MONITOR, or Streamed screen in the console) skips virtual-output creation entirely and is the workaround while you sort the above out.
Black screen / no picture: confirm you're on a Wayland session (not X11) and, on NVIDIA, that the GL userspace is installed. More in Troubleshooting.

To bring the console up and pair, see The Web Console.

KDE Plasma (KWin)