fegger
47905004eb
The receiver does not need a window manager: SDL3's KMSDRM backend renders straight to the kernel display pipeline, which is the right setup for a small-board appliance. But a systemd system service has no controlling terminal, and SDL's KMSDRM backend expects one for its VT handling — so the headless path would have failed at boot. Give the unit StandardInput=tty with TTYPath=/dev/tty1 (harmless in desktop mode), and document the headless recipe in the unit, the install script output, and the RUNBOOK: Raspberry Pi OS Lite with Console Autologin, no desktop enabled (a compositor would hold the DRM master), and consoleblank=0.
59 lines
2.2 KiB
Desktop File
59 lines
2.2 KiB
Desktop File
# screencast-receiver.service — autostart for the receiver.
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#
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# This file is a template: scripts/install-receiver.sh substitutes
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# __SC_RECEIVER_BIN__ and __SC_RECEIVER_USER__ before installing it to
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# /etc/systemd/system/screencast-receiver.service.
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#
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# Display environments:
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#
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# 1. Headless console (SDL renders via KMSDRM): works as installed. The
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# configured User needs access to /dev/dri and the input devices; the
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# install script adds it to the video/render/input groups.
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#
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# 2. Graphical session (Wayland or X11 desktop with autologin): uncomment
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# the Environment lines in [Service] and adjust them to the session
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# owner (XDG_RUNTIME_DIR usually lives in /run/user/1000).
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[Unit]
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Description=Screencast receiver (H.264 over RTP/UDP)
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Wants=network-online.target
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After=network-online.target avahi-daemon.service
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# Give slow-booting boards (and desktop sessions that start late) a chance;
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# systemd's default limit would give up after 5 fast failures.
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StartLimitIntervalSec=30
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StartLimitBurst=10
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[Service]
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Type=simple
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User=__SC_RECEIVER_USER__
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ExecStart=__SC_RECEIVER_BIN__ --receive
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# SDL's KMSDRM backend (headless console) expects a controlling terminal
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# for its VT handling; system services have none by default. Harmless in
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# desktop mode, where the process never touches the tty.
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StandardInput=tty
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TTYPath=/dev/tty1
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# SIGTERM (systemctl stop) shuts the receiver down gracefully, which
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# withdraws its mDNS announcement. Never SIGKILL it; the systemd default
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# KillMode escalates only after the graceful timeout.
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KillSignal=SIGTERM
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TimeoutStopSec=10
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Restart=on-failure
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RestartSec=3
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NoNewPrivileges=true
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PrivateTmp=true
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# Graphical session: uncomment and adjust to the session owner.
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#Environment=XDG_RUNTIME_DIR=/run/user/1000
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#Environment=WAYLAND_DISPLAY=wayland-0
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#Environment=DISPLAY=:0
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[Install]
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WantedBy=multi-user.target
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# Headless console recipe (no window manager needed — SDL renders directly
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# to the kernel via KMSDRM):
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# * Raspberry Pi OS Lite, no desktop enabled (a running compositor would
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# hold the DRM master and the receiver could not take it)
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# * raspi-config → System Options → Boot → Console Autologin
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# * disable console blanking: add consoleblank=0 to
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# /boot/firmware/cmdline.txt |