Mesa 26.1 brings another fix for ATI R300 to R500 graphics cards
Open-source ATI R300 driver gets occlusion query fix in 2026.
Mesa’s legacy ATI r300 driver has received another update in 2026. Phoronix reports that independent developer Pavel Ondračkar fixed occlusion query support for the old driver stack used by ATI R300 through R500 class GPUs, and the change has already landed in Mesa 26.1-devel for the next quarterly release.
Phoronix quotes Ondračkar saying:
“This is my attempt to fix the occlusion queries. There was a previous one by @mareko in 2012 which was however later reverted since it broke HyperZ. This approach should hopefully be much less invasive (the dummy z buffer is used only when there is active query), and the tests seem happy. I’ve done also some usual app testing: Unigine, Lightsmark, some wined3d and all seems fine, but more real-world testing would be appreciated OFC.”
For readers unfamiliar with the naming, R300 usually refers to ATI’s Radeon 9500 to 9800 generation . X.Org’s Radeon family mapping also places related X300 to X600 parts and some mobile derivatives in the R300 bucket. In Mesa terms, though, the r300 driver covers a wider range than the name suggests, spanning R300, R400, and R500 hardware, which means support extends into later Radeon X700, X800, and X1000-era cards as well.
Occlusion queries are an OpenGL feature that lets software check whether rendered objects were actually visible, instead of fully hidden behind other geometry. It is a small part of the graphics stack, but it still matters for correctness and compatibility on old hardware, especially when these cards remain usable through Linux’s open-source driver path long after official vendor support ended.
Ondračkar is still working on another R300-area fix related to HyperZ behavior on large surfaces. That means Mesa’s oldest ATI driver branch is still seeing maintenance in 2026, even for GPUs that first appeared more than two decades ago.
Source: Phoronix
