Doom 2016 Vulkan not loading with Vega M hardware (379720)

Hello Everyone,
I believe I've discovered a edge case bug that affects laptop users that have both an integrated GPU and a discrete GPU. In my case I have a system with a Vega M.

Current System Info:
Kernel: 4.18.5
Mesa: 18.3+
GPU: AMD Vega M

Description of the Problem:

Edit: I appear to have been mistaken. The DRI_PRIME environment variable is being passed into to DOOMx64vk.exe. The issue is that when running DOOM with Vulkan (r_renderapi 1) the game does not load (stuck at 99% and menu never appears).

I'm not 100% sure what's going on, but one possibility is that DOOM is not using the discrete Vega M GPU and instead using the Intel iGPU. I tried to force the use of the Vega M GPU by:

• Removing the intel_icd* files in /usr/share/vulkan/icd.d directory.
• Setting the VK_ICD_FILENAMES environment variable to explicitly point to the radeon_xxx.icd for the Vega M

The other possibility is that there is a bug with RADV (Mesa) on Vega M hardware with DOOM. This seems more unlikely though, as I'm able to run other games via Proton + DXVK with no problems.

When setting the following launch options:
DRI_PRIME=1 %command% +r_renderapi 0 (OpenGL)
The Vega M GPU is used and I have no problems - the game runs flawlessly.

Start by reproducing the reported hang at 99% with DOOMx64vk.exe on Vega M hardware, using r_renderapi 1 and the documented DRI_PRIME and VK_ICD_FILENAMES settings. Compare Vulkan and OpenGL launch behavior and determine whether the issue is in process environment handling or RADV hardware support. Done means the Vulkan game reaches its menu on the discrete GPU, with the relevant cause and validation recorded.