Intel Gallium3D "Iris" Driver Changes Merged For Rusticl's OpenCL 3.0

While Intel's Compute-Runtime stack is fully open-source and already provides OpenCL 3.0 support for recent generations of Intel graphics under Linux, it looks like the recently-merged "Rusticl" Rust OpenCL implementation in Mesa will soon be working too on Intel graphics hardware as an alternative OpenCL 3.0 implementation.

Last week Mesa 22.3 merged Rusticl as the Rust-written Gallium3D OpenCL driver worked on by Karol Herbst at Red Hat. This Rust-written CL driver provides OpenCL 3.0 support complete with CL image support and working for various OpenCL-using applications.

Jason Ekstrand of Collabora recently took care of Intel Iris driver changes for splitting up some limits and setting up support for up to 128 textures and up to 64 images. Those Intel Iris driver changes were merged a few minutes ago, which are needed for Rusticl compatibility as noted by Jason and Karol. Karol commented, "Really need this for getting iris CL 3.0 compliant with rusticl :)"

In addition to the Intel Iris driver, the Rusticl work has been testing too with the Nouveau Gallium3D driver, the swrast software fallback, and earlier this week Panfrost support was added too for Arm Mali OpenCL.

Also on the Rusticl front is this MR that is still under review for reducing the kernel launch overhead.

While Intel has provided great OpenCL support for years with their "NEO" Compute-Runtime stack (and before that with the Beignet project!), a benefit of the Rusticl support is that it's all mainline within Mesa and available in many Linux distribution repositories. The number of Linux distributions actively packaging the Compute-Runtime, Intel Graphics Compiler, and related dependencies is much smaller, so at least if this Rusticl support pans out nicely this is a nice way to enjoy OpenCL with UHD Graphics / Arc Graphics if not wanting or able to install Intel's full compute stack.