Valve has been sponsoring Collabora engineers with early phase, exploratory work for trying to bring the open-source Radeon Vulkan "RADV" driver to Microsoft Windows.

Experimental work is underway for porting the Mesa RADV Vulkan driver to Windows as this open-source driver implementation used by Linux gamers and a large part to the success of the AMD-powered Steam Deck and now Steam Machine. Valve funds multiple developers working on the open-source RADV Vulkan driver and other portions of the Linux graphics stack. Now they are sponsoring Collabora developers in trying to make RADV viable on Microsoft Windows.

Louis-Francis Ratté-Boulianne put out a blog post highlighting their initial work on porting RADV to Windows. Besides working on Windows WDDM2 integration for Windows, a big challenge with porting RADV to Windows is on relying on the AMD Radeon Software Windows kernel driver.

It's out-of-scope of this current work for trying to port the AMDGPU Linux kernel graphics driver to Windows, so they are working on bringing RADV to Windows while relying on AMD's official Windows kernel driver. That in turn has led to reverse engineering and other steps for figuring out the proprietary kernel driver's data structures and other elements so RADV can be adapted to use it.

Ultimately for this to really work out well, they either need a stable and documented interface to the AMD kernel graphics driver on Windows or to create a shim library that can sit between RADV and the kernel driver as a stable interface to work through the undocumented changes between AMD Radeon Software Windows driver releases.

As shown in the blog post, they have been successful in demoing Counter-Strike 2 with RADV on Windows:

The experimental code can be found via this development branch.