On a hybrid laptop whose Wayland compositor runs on the discrete GPU
(Hyprland with AQ_DRM_DEVICES naming the NVIDIA card first), the built-in
panel still hangs off the integrated GPU, so the panel rule (#8) picked it,
and the window stayed empty: the compositor took the frames and showed
nothing, with no error anywhere.
Which GPU drives a display stands in for which GPU the compositor draws
with. Under Wayland the compositor says so itself: the main_device of its
linux-dmabuf feedback (version 4), the device it imports client buffers on,
which Mesa's Vulkan device-select layer reads for the same purpose.
compositor_gpu.rs asks for it on a short-lived connection, maps the dev_t
to PCI ids through /sys/dev/char, and pick_adapter ranks that adapter
first. No answer (X11, an older compositor, a GPU no adapter matches)
leaves the existing rules in charge, and WGPU_POWER_PREF still overrides.
wayland-client and wayland-protocols are already in the tree through winit;
they become direct Linux-only dependencies.
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