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Stage 6 — Real Display (DRM/KMS)

What it is. Moving off the nested Wayland backend and onto real display hardware: a bare virtual terminal, DRM/KMS modesetting, and a real login session via libseat, instead of a window inside someone else’s compositor.

Deliverable (from KICKOFF.md): run on a VT via seatd/libseat; multi-output layout and modesetting. 0xide as a real session on hardware/VM.

How it’s gone so far

wlr_backend_autocreate already picks the DRM/KMS backend automatically when there’s no WAYLAND_DISPLAY to detect — no separate code path was needed, just a different environment to run in. On a bare TTY: LIBSEAT_BACKEND=logind ~/Projects/0xide/target/debug/0xide foot 2>~/0xide-tty.log, with LIBSEAT_BACKEND=logind letting logind hand the active VT its devices without a seat group membership.

Two real bugs came out of this that a nested session can’t surface at all, since nesting never tears down or re-modesets an output:

  • VT switching crashed on output destroy. Switching away and losing the session mid-flight needed proper output-destroy handling — removing the frame/destroy listeners and background scene node before wlroots finishes tearing the output down, or wlroots asserts on a non-empty frame listener list.
  • Returning from a VT switch came back black. The outputs aren’t destroyed on a VT switch — they’re re-modeset to black — and idle clients never repaint on their own, so regaining the VT showed nothing. The fix hooks the session’s active-change signal: on resume, every window’s scene node is torn down and recreated (a client’s buffer survives, but its old scene node stops presenting it after the modeset), then a few forced repaints are scheduled per output so the freshly-rebuilt scene actually gets painted once the output is back.

Multi-output tiling (per-output workspaces, focus-follows-monitor, config-driven position/scale) was built and verified nested first — see Stage 5 — and confirmed working the same way on real hardware.

Status

In progress / substantially working. Single and multi-display both run on real hardware, VT switching survives without crashing or losing windows, and config-driven monitor placement matches real connector names and dimensions. Not yet covered: hotplug removal mid-session beyond the already-handled destroy path, and further real-hardware edge cases as they turn up.