Forced GPU selection prevents wgpu running on hybrid nvidia laptops

[flukejones]

The block at

wgpu/wgpu-hal/src/vulkan/instance.rs

Line 771 in 625afc3

if cfg!(target_os = "linux") && has_nvidia_dgpu && self.shared.has_nv_optimus {

is an issue. On hybrid nvidia laptops it is preventing running wgpu based applications completely.

So what is happening for every Nvidia hybrid user is:

1. Intel GPU is blocked so it's impossible to select it
2. Nvidia will never work either due to WL Vulkan apps are broken with PRIME NVIDIA/egl-wayland#72
3. wgpu based apps just will not work (such as wgpu surface_configure fails (intel+nvidia hybrid laptop) lapce/floem#100 and all wgpu examples)

Given the above, this commit should be reverted, and be done before the next release of wgpu.

Related: #1215 (nvidia provides ways to force nvidia gpu selection)
Related: #1898 (the commit)

[teoxoy]

I think we should apply the workaround conditionally on the mesa version.

[flukejones]

@teoxoy mesa version of?

This block also prevents the use of Nvidia GL btw.

[teoxoy]

The "block" was added to work around a bug in mesa. We should find the version of mesa in which it was fixed and conditionally apply the workaround on it.

This block also prevents the use of Nvidia GL btw.

That is most likely a different issue. This workaround is only present in our Vulkan backend.

[flukejones]

Mesa for what though, intel? I'm using mesa-vulkan-drivers-23.2.0~rc2-3.fc40.x86_64. And the previous version also works fine.

To be as clear as I can, current wgpu will never work on hybrid with that block due to NVIDIA/egl-wayland#72

[teoxoy]

Mesa for what though, intel? I'm using mesa-vulkan-drivers-23.2.0~rc2-3.fc40.x86_64. And the previous version also works fine.

The fix upstream got released as part of mesa 21.2.

To be as clear as I can, current wgpu will never work on hybrid with that block due to NVIDIA/egl-wayland#72

Right now it works on x11, but not on Wayland.

Would you be interested in contributing the fix?

[flukejones]

Would you be interested in contributing the fix?

Sure I don't mind.