RADV Driver Adds Support For Valve's New VKD3D-Proton Focused Vulkan Extension

Mesa's Radeon Vulkan driver "RADV" has now added support for the recently published VK_VALVE_descriptor_set_host_mapping Vulkan extension.

VK_VALVE_descriptor_set_host_mapping was published last week with the Vulkan 1.3.207 spec update. As outlined in that prior article, this is a new vendor-specific Valve extension for allowing applications to directly query a host pointer for a Vulkan descriptor set. As also mentioned there, the extension is only lightly documented and focused on VKD3D-Proton usage for accelerating Direct3D 12 atop Vulkan.

VKD3D-Proton's recent v2.6 release adds support for using the VK_VALVE_descriptor_set_host_mapping and it helps with overhead reduction on platforms like the Steam Deck.

Mainline Mesa now has enabled VK_VALVE_descriptor_set_host_mapping for RADV. This merge request adds this Valve extension to RADV thanks to the work of Bas Nieuwenhuizen and Hans-Kristian Arntzen.

Worth noting is that the VK_VALVE_descriptor_set_host_mapping extension is designed exclusively for VKD3D-Proton usage and the extension is only even being advertised by RADV if the exposed Vulkan instance engine name is "vkd3d".