Mesa Merges A Common Vulkan Layer For Working Around Cross-Driver Game Bugs

Merged to Mesa 27.0-devel is a new common Vulkan layer within Mesa's Vulkan Runtime for being able to carry common game/engine/app workarounds that affect multiple drivers. The Radeon RADV and NVIDIA NVK Vulkan drivers both rely on a Vulkan layer to workaround some app bugs directly from Vulkan entrypoints. Now there is a common solution in the Mesa Vulkan Runtime for being able to handle this by drivers opting into it and where the issues aren't driver-specific. This new infrastructure was also used for introducing a new workaround for the Metro Exodus game. The Metro Exodus workaround is due to the game sometimes passing NULL to pWaitSemaphores, which is invalid per the Vulkan API specification. This workaround in the common layer is now addressing that illegal behavior so the Mesa Vulkan drivers cope fine. The bug was reported back in 2023. NVK and RADV are the initial users of this common layer while with time other Mesa Vulkan drivers can join.Those interested in this work by Valve's Samuel Pitoiset can learn more via this merge.