Maxwell OpenGL Improvements Coming To Nouveau

In addition to the GeForce GTX 900 "Maxwell" open-source driver support on Nouveau being in rough shape due to lack of re-clocking / power management for allowing sufficient performance, the NVC0 Gallium3D driver for Maxwell has also lagged behind with some OpenGL 4.x features on the GTX 900 GPUs.

Longtime Nouveau developer Samuel Pitoiset has been working in part to help this situation for poor Maxwell open-source support by tackling ARB_shader_image_load_store and ARB_shader_image_size.

Pitoiset has posted these shader image patches for Maxwell to the Mesa mailing list but he hasn't yet landed them in Mesa Git and the ARB_shader_image_load_store isn't enabled by default. With the current ARB_shader_image_load_store patches there are still some issues to address.

For now the Maxwell support on Nouveau exposes only OpenGL 3.3 as a blocker for GL4 is tessellation support, which Samuel commented, "I'm working on [tessellation] but it's quite hard"

More details here. Long story short, the most suitable open-source Nouveau driver performance remains with the GeForce GTX 600/700 "Kepler" GPUs.