R600 Gallium3D Driver For Old Radeon GPUs To See Rewritten NIR Backend

While AMD's official graphics driver on Windows has effectively moved to legacy pre-Polaris graphics card support, in the open-source world on Linux even the old "R600" Gallium3D driver for Radeon HD 2000 through HD 6000 series graphics cards sees the occasional new feature work by the community. The latest is a new NIR back-end being rewritten for this R600g driver and should debut soon.

Open-source developer Gert Wollny is among the few still actively working on the Radeon R600g driver in Mesa for doing more than just simple bug fixing. In particular, he has been working a lot on NIR support for R600g for using that intermediate representation (IR) alternative to Gallium3D's TGSI. Aside from already having written a NIR implementation for R600g, he's recently been rewriting it to make it even better for using that IR for handling of OpenGL shaders in a more efficient and optimized manner than the crusty TGSI route with NIR being far preferred by upstream Mesa developers as the modern graphics driver IR.

10+ year old Radeon graphics cards still seeing new open-source GPU driver work on Linux.

In a recent Mesa bug report he alluded to the fact that he'll soon be introducing a new NIR back-end for R600g, "The nir backend is currently being rewritten. I've tested your trace on the new branch and it worked on Cayman (HD 6950) and Cedar (HD 5450). I hope to be able to merge the new nir code in a week or so."

Sounds like a nice Easter surprise. While the R600 Gallium3D driver supports from the Radeon HD 2000 "R600" through Radeon HD 6000 "Northern Islands" graphics cards, much of the NIR work and other recent R600g feature work has mostly been focused on the HD 5000/6000 series graphics cards for being the most capable of the supported bunch.

We'll see how this R600g NIR rewrite pans out for next quarter's Mesa 22.2.