Intel Gallium3D Driver Merged Into Mesa 21.2 For Gen4 Through Haswell Graphics
Intel has in recent years developed the Iris Gallium3D driver providing great support for Broadwell graphics and newer. The "i965" classic driver meanwhile was left for supporting Intel Haswell graphics and older. The i965 classic driver doesn't see much activity these days and with Mesa developers talking of possibly dropping classic drivers from mainline, David Airlie and Ilia Mirkin along with others developed this driver called Crocus.
Again, it's just about a Gallium3D driver for old Intel graphics hardware and if you are using Broadwell or newer this isn't of relevance to you since on that front is the excellent Iris Gallium3D driver already.
There still are at least a number of Intel Haswell Linux users out there given the popularity of those processors from eight years ago.
Crocus has been getting into shape over the past few months and earlier this month the WIP merge request opened for this Gen4 to Gen7 driver. The driver in its current state is considered "pretty fully functional Gallium driver" but for now the default build continues to be the i965 classic driver.
Mesa 21.2 will be out next quarter with this driver and many other improvements. The merge of Crocus adds around 28.5k lines of code.