Intel Now Aiming For Gallium3D OpenGL Default For Mesa 20.0

While we had been eager for Intel's goal of defaulting to their new Gallium3D OpenGL Linux driver by EOY2019, it looks like that is going to swing by one quarter with the plan now for Mesa 20.0 at the end of Q1.

For the better part of two years now Intel has been working on this new "Iris" Gallium3D driver for supporting Broadwell "Gen8" graphics and newer as the eventual replacement to their long-standing i965 classic driver. With Tiger Lake "Gen12" Xe graphics, it's in fact Iris Gallium3D only. In our testing of Broadwell through the *lakes, this Gallium3D driver has been working out terrific on Mesa 19.2 stable and Mesa 19.3 development. But it looks like Intel is going to play it safe and punt the default change-over to next quarter's Mesa 20.0 cycle.

In our results over the past month we've seen faster performance out of their Gallium3D driver including for their older Broadwell graphics. With yesterday's Windows 10 vs. Linux Icelake graphics tests, the Iris Gallium3D driver again proved to be beneficial compared to i965 classic.

Intel's Lisa Pearce as the Graphics Software Engineering Director has shared with us that the default change is now planned for Mesa 20.0:

Thanks @phoronix for running all this data! We see some different results on some cases (Dota2 & Portal) and Ken G will get in touch with you to root cause. On making Gallium 3D stack default, it is trending to Mesa 20.0 not 19.3 to ensure no destabilization for users.

— Lisa Pearce (@gfxlisa) October 16, 2019

The delay is for helping to ensure "no destabilization for users" as possibly some corner cases still to address.

While it's a bummer not seeing this change happen for Mesa 19.3, for users on the likes of Ubuntu 19.10 can already easily "switch" over to the new OpenGL driver via the MESA_LOADER_DRIVER_OVERRIDE=iris environment variable. Give it a whirl and see how well Intel Gallium3D works out for you otherwise report any regressions for helping this open-source driver get over its last hurdle.

Mesa 20.0's feature cycle will kick off in mid-to-late November (given the usual likelihood for delays in Mesa's branching of the current cycle) while it should debut as stable around the end of February or early March. Mesa 20.0 should be out in time for making it into the likes of Ubuntu 20.04 LTS and Fedora 32.