Fake Sparse Support Being Worked On For Intel's Open-Source Vulkan Driver

While Intel Arc Graphics continue enjoying performance optimizations with the open-source Linux graphics driver stack, the major limitation facing Arc Graphics on Linux right now for gamers is the lack of sparse residency support that is needed for running many newer games on Linux with Intel graphics -- particularly newer Windows D3D12 titles running on Linux via Valve's Steam Play. It's been a long known limitation and will hopefully be addressed once the Intel Xe kernel driver is introduced, but at least as an interim solution there is now "fake" sparse support being implemented.

Felix Degrood of Intel's Portland Linux graphics driver crew has been working to implement "fake" sparse support for the ANV Mesa driver. Degrood notes that some DirectX 12 games require sparse resource support but don't actually make use of sparse resources. So this fake support is around advertising sparse support even if not fully implemented. Setting "fake_sparse=true" can be done then by users as an override or white-listed games in DriConf for known games needing sparse support but not depending upon sparse resources.

Elden Ring is one game now able to work with the Intel graphics driver on Linux via this fake sparse support. Other games are currently being analyzed for seeing what other titles will benefit from this fake sparse support.

The Intel ANV fake sparse support hasn't yet been merged to Mesa but is available via this merge request. It also depends on this MR with the sparse residency compiler code. This is at least a nice stop-gap measure for some games while hopefully later this year we'll see the experimental Intel Xe DRM driver mainlined to the Linux kernel as that modern i915 alternative for newer generations of Intel graphics where we may see further performance improvements, better multi CPU architecture support, and the necessary kernel-side bits for proper sparse support.