The Open-Source ATI R300 Graphics Driver Is Still Being Improved Upon In 2024

It's been over twenty years since the ATI Radeon R300 series was introduced but thanks to the open-source Mesa Gallium3D OpenGL driver, there continues to be new improvements made to this driver for these aging Radeon graphics cards on Linux. A few hundred lines of code were merged today for further enhancing the ATI R300 Gallium3D driver in 2024.

The Mesa R300g driver supports from the Radeon R300 series up through the R500 (Radeon X1000 series) graphics cards. The Mesa R300g driver has long been worked on for supporting the pre-R600 series hardware and has been very mature for years but continues to see occasional refinements for optimizing performance, fixing the occasional bug, or adapting to new Mesa interfaces/features like the transition to the NIR intermediate representation. Over the past decade much of the R300g improvements have come from the open-source community with AMD engineers principally focused on current generation and future hardware. But thanks to all the code being public and open-source, it's a welcoming opportunity compared to the proprietary ATI/AMD Radeon hardware support for R300 through R500 series -- and much newer GPUs -- long being in maintenance mode.

The code merged today for the R300g driver is implementing more NIR lowering for vertex shaders. Independent open-source developer Pavel Ondračka explained in the merge:

"This MR moves the most of the remaining backend lowering into NIR. Specifically, ftrunc, fcsel (when suitable) and flrp. The backend lowering paths are removed. This is a prerequisite for more backend cleanups, for example I have a MR ready to get rid of backend DCE for vertex shaders.
...
Shader-db-wise this is a bit of a win for R500 (by doing the fcsel lowering in nir, we still have info if this is fcsel_lt/ge or fcsel and we can save the comparison for the later case if we have to lower it), and mostly even on R300 see individual commits for detailed stats."

This additional R300g NIR lowering work will be found in this quarter's Mesa 24.0 stable release -- should you still be using any Radeon R300 through R500 series graphics cards.

Though given the age of these Radeon GPUs, there is far better performance and power efficiency with newer hardware but at least thanks to being open-source the Linux driver support lives on.