RADV Working Toward D3D12 FL 12.2 Support With VKD3D-Proton

The Mesa Radeon Vulkan driver "RADV" is seeing work towards being able to support Direct3D 12 Feature Level 12.2 with VKD3D-Proton to further enhance the Steam Play gaming experience on Linux.

Last week Valve developer Hans-Kristian Arntzen opend a new Mesa issue, who is known for his work particularly on VKD3D-Proton for Direct3D 12 over Vulkan and is part of Steam Play. The issue is over lack of support for fullyCoveredFragmentShaderInputVariable from the VK_EXT_conservative_rasterization extension. On AMD RDNA2 and newer GPUs, this functionality is needed to get Direct3D 12 Feature Level 12.2 working.

Prolific RADV developer Samuel Pitoiset at Valve is on it and working towards this milestone. Merged so far is preliminary work in that quest by enabling "primitiveUnderestimation" support for GFX9/Vega and newer.

Not yet merged and currently in his personal branch, Pitoiset has this patch getting the functionality working on GFX9+ to unblock the D3D12 FL 12.2 support. Hopefully we'll see that land in Mesa 23.1 in the coming days.

The Direct3D 12 FL 12_2 spec for those interested can be found here.