Failure to find hardware adapter

[a1phyr]

Description
On master with OpenGL, wgpu only finds software adapter (llvmpipe) but it works as expected with v0.12

Repro steps
Run wgpu-info, look for the OpenGL adapter

Expected vs observed behavior
Expected behavior: I get a hardware adapter for OpenGL (AMD or NVIDIA if PRIME is enabled) like in wgpu 0.12
Observed behavior: I get a software adapter for OpenGL (llvmpipe)

I also get an error: EGL 'eglInitialize' code 0x3001: DRI2: failed to create screen

Extra materials
Bisecting the issue shows that it comes from 70db03d (#2339)

Failing logs for RUST_LOG=info wgpu-info

[2022-02-28T13:31:40Z WARN  wgpu_hal::vulkan::instance] Unable to find layer: VK_LAYER_KHRONOS_validation
[2022-02-28T13:31:40Z INFO  wgpu_hal::vulkan::instance] Instance version: 0x4030cc
[2022-02-28T13:31:40Z INFO  wgpu_hal::vulkan::instance] Enabling debug utils
[2022-02-28T13:31:40Z INFO  wgpu_hal::vulkan::instance] Enabling device properties2
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Loading Wayland library to get the current display
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Loading X11 library to get the current display
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] No windowing system present. Using surfaceless platform
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Enabling EGL debug output
libEGL warning: DRI2: failed to create dri screen
[2022-02-28T13:31:40Z ERROR wgpu_hal::gles::egl] EGL 'eglInitialize' code 0x3001: DRI2: failed to create screen
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Display vendor "Mesa Project", version (1, 5)
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	EGL surface: +srgb
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	Trying native-render
[2022-02-28T13:31:40Z WARN  wgpu_hal::gles::egl] No config found!
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	Trying presentation
[2022-02-28T13:31:40Z WARN  wgpu_hal::gles::egl] No config found!
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	Trying off-screen
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	EGL context: +debug
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	EGL context: +robust access
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] 	EGL context: +surfaceless
[2022-02-28T13:31:40Z INFO  wgpu_core::instance] Adapter Vulkan AdapterInfo { name: "AMD RADV RENOIR", vendor: 4098, device: 5686, device_type: IntegratedGpu, backend: Vulkan }
[2022-02-28T13:31:40Z INFO  wgpu_core::instance] Adapter Vulkan AdapterInfo { name: "NVIDIA GeForce GTX 1650", vendor: 4318, device: 8089, device_type: DiscreteGpu, backend: Vulkan }
[2022-02-28T13:31:40Z INFO  wgpu_core::instance] Adapter Vulkan AdapterInfo { name: "llvmpipe (LLVM 12.0.1, 256 bits)", vendor: 65541, device: 0, device_type: Cpu, backend: Vulkan }
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Max label length: 256
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::egl] Enabling GLES debug output
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::adapter] Vendor: Mesa/X.org
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::adapter] Renderer: llvmpipe (LLVM 12.0.1, 256 bits)
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::adapter] Version: OpenGL ES 3.2 Mesa 21.2.6
[2022-02-28T13:31:40Z INFO  wgpu_hal::gles::adapter] SL version: OpenGL ES GLSL ES 3.20
[2022-02-28T13:31:40Z INFO  wgpu_core::instance] Adapter Gl AdapterInfo { name: "llvmpipe (LLVM 12.0.1, 256 bits)", vendor: 0, device: 0, device_type: Cpu, backend: Gl }

Platform
Debian testing + X11

[CasualPokePlayer]

The issue here is that libX11.so simply doesn't exist usually. That .so will only be available if the libx11-dev package is installed. Otherwise, only libX11.so.6 will be available. If the user happens to already have the libx11-dev package (or maybe the distro provides a libX11.so regardless), then this issue ends up going away for them.

[cwfitzgerald]

So the solution would be to look for libX11.so.6 as well?

[grumpyLxr]

@cwfitzgerald: Yes that should be the solution. Installing libx11-dev adds a symbolic link from libX11.so to libX11.so.6. So the correct way should be to look for libX11.so and if that cannot be found to look for libX11.so.6.

[cwfitzgerald]

Alright, happy to have a PR to add that behavior

[vorporeal]

Happy to send a PR for this! One question:

On Wayland, libwayland-client.so.0 is tried before libwayland-client.so. Would we want the same behavior for X11 (libX11.so.6 before libX11.so) or should it be the reverse order, as @grumpyLxr suggested above?

[vorporeal]

Opened #5307 to try loading libX11.so.6 before libX11.so.