Mesa 27.0 update enables Vulkan FP16 for AMD GFX8 GPUs

Valve landed a patch in Mesa 27.0 on October 22, 2026, that turns on Vulkan FP16 support by default for specific older graphics cards running VKD3D-Proton. The change affects AMD GFX8 hardware, covering GCN third and fourth-generation architectures from Tonga up to Radeon RX 400 and RX 500 Polaris series cards.

Georg Lehmann explains that newer Windows games increasingly require FP16 support. The default activation resolves issues like broken ambient occlusion in The Witcher 3 following recent game updates.

Lehmann notes that the driver previously kept the radv_enable_float16_gfx8 option disabled by default. Developers avoided forcing FP16 across the board because it rarely improves performance and can run slower than FP32 on legacy silicon. The backport to current Mesa stable series ensures these older GPUs handle select modern titles without manual configuration.