Intel's i965 Mesa Classic OpenGL Driver Will Stick Around A Bit Longer
Removing the long-standing Intel open-source i965 Mesa driver has been a possibility since earlier in the year when the "Crocus" Gallium3D driver was merged and has matured into good shape for providing accelerated OpenGL on old Intel 965 chipsets through Haswell. It's with Broadwell and newer where Intel's Iris Gallium3D driver has come together nicely and continues to work great through Xe Graphics. So between Crocus and Iris, Intel's OpenGL driver is in a solid footing now.
Crocus in my own tests have found to be in good shape after the initial fixes post-merging and the performance is generally similar to i965 or often times in much better shape. Since September, Crocus was added to the Mesa default driver build list.
With Fedora Workstation 35, Crocus is being used by default. For others running Mesa 21.2+ with the Crocus driver being built, changing over can be as easy as setting the MESA_LOADER_DRIVER_OVERRIDE=crocus environment variable. Other Linux distributions will likely default to Crocus in coming releases.
Given the good shape of Crocus, Mesa is now in a position to remove the i965 classic driver and in turn remove the classic (non-Gallium3D) Mesa OpenGL code now that there are no other major users left of that classic architecture. For a half-year has been the merge request to delete classic Mesa from the tree.
Deleting classic Mesa didn't happen for Mesa 21.3 as was discussed as a possible target before, but it looks like it will be removed in 2022. Intel Linux graphics driver developer Jason Ekstrand recently commented on the classic Mesa deletion PR:
For the sake of i965 (which I just fixed a bug in!), my feeling is to let this sit a few more months. Fedora 35 just shipped with crocus on by default. That should give us a good opportunity to see how it does in the wild. If that goes smoothly, I'll feel reasonably comfortable telling the other distros to do the same in the spring cycle and dropping i965 from the tree.
So hopefully by next spring we'll be able to see classic Mesa finally retired. Removing classic Mesa will lighten the massive code-base of these open-source OpenGL/Vulkan drivers by some 50k lines of code.