Fix Vulkan device selection on Intel+NVIDIA PRIME systems#315
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Detect multi-GPU topology via sysfs and the display server via environment variables, then hard-reject adapters that are known to fail presentation: - X11: reject Intel iGPU (Mesa bug #4688) - Wayland: reject NVIDIA dGPU (surface owned by compositor's GPU) Replaces the Ubuntu-specific /etc/prime-discrete heuristic. https://claude.ai/code/session_01W9jSvpnbXEXmoHFuUVFdUN
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Summary
/etc/prime-discreteheuristic with proper multi-GPU detection/sys/bus/pci/devices/) — zero Vulkan overheadWAYLAND_DISPLAY/DISPLAYenvironment variablesBackground
On Linux systems with both Intel iGPU and NVIDIA dGPU (PRIME topology), Vulkan presentation
is broken for one of the two GPUs depending on the display server:
This is an architectural limitation in the Linux Vulkan ecosystem — there is no automatic
cross-GPU presentation mechanism. The issue spans NVIDIA drivers 460.x–570.x and Mesa 23.x–25.x,
confirming it is systemic rather than a single driver bug.
The previous workaround read
/etc/prime-discrete, which is Ubuntu-specific and did notdistinguish between X11 and Wayland (where the opposite GPU is broken).
Test plan
detect_gpu_vendors()returns one entrydevice_idoverride still works to force a specific adapterdetect_gpu_vendors()returns empty, no rejectionsCloses #205