IBM engineers announced they are deprecating the upstream CXL and CXLFLASH Linux kernel drivers with plans to then remove the drivers from the mainline kernel the following cycle. Before getting too worked up when seeing the "cxl: Deprecate driver" patch, this is about the Coherent Accelerator Processor Interface (CAPI) that predates the Compute Express Link.

IBM is deprecating and then soon thereafter removing the CXL and CXLFLASH drivers from the Linux kernel as being obsolete and deprecated. This is around their Coherent Accelerator Processor Interface for connecting POWER CPUs to GPUs, ASICs, FPGAs, and high speed storage. This is not to be confused with the modern CXL (Compute Express Link) code within the Linux kernel that continues to be actively developed as a modern interconnect standard.

The [1]patch series cover letter explains:

"This series marks the cxl and cxlflash drivers as obsolete/deprecated, disables them by default, and prints a warning to users on probe.

CAPI devices have been out of production for some time, and we're not aware of any remaining users who are likely to want a modern kernel. There's almost certainly some remaining driver bugs and we don't have much hardware available to properly test the drivers any more.

...

This series will be followed up with patches to remove the drivers and associated arch code, which I hope will be merged in the following cycle."

So in 2025 we're likely to see the Linux kernel formally deprecate support for IBM CAPI driver support followed by removing these CXL and CXLFLASH kernel drivers in a follow-up cycle.



[1] https://lore.kernel.org/lkml/20241210054055.144813-1-ajd@linux.ibm.com/