Mesa 25.0 Clover OpenCL Drops Support For NIR Drivers

As part of the transition to eventually drop the long dormant Clover OpenCL state tracker from Mesa's Gallium3D codebase in favor of the modern OpenCL Rusticl Rust-written driver, Mesa 25.0 has ended Clover support for NIR-based drivers.

Rusticl has been maturing well for a modern Rust-based OpenCL driver for use with Mesa Gallium3D hardware drivers. Rusticl is exposing OpenCL 3.0, well maintained, working with an increasing number of drivers, and much better off than the effectively dead Clover code. Clover hasn't seen much feature activity in years... The last time AMD, for example, was contributing to Clover was in the pre-ROCm days.

Red Hat engineer Karol Herbst who leads Rusticl development has finally been able to merge the eight month old merge request for ending NIR-based driver support by Clover. Herbst commented there:

"Development basically is non existent and it allows for some clean ups and space savings.

[As far as I know] there are no reasons to not do this. This also drops PIPE_SHADER_IR_NIR_SERIALIZED which is something that shouldn't have been added in the first place."

Dropping the NIR driver support from Clover lightens the Mesa codebase by nearly two thousand lines of code. This change is merged for next quarter's Mesa 25.0 release. Eventually the Clover code itself will be completely removed from the Mesa codebase in favor of Rusticl.