If all goes well, the re-enabling could come for Linux 5.16 later this year - still ahead of Sapphire Rapid's ramp in Q2. We'll see though if the upstream kernel maintainers are happy now with the state of the code or further alterations will be required. With this set of patches, ENQCMD is looking to be re-enabled. Intel originally upstreamed the ENQCMD work since last year. But the initial Linux kernel support code was in poor shape - including insufficient protection against FPU state modification - and led to it being disabled upstream. The ENQCMD instruction (and ENQCMDS) allows atomically submitting a work descriptor to a device and part of the Data Streaming Accelerator debuting as part of next year's Sapphire Rapids processors. This summer the mainline Linux kernel disabled ENQCMD support since the code was 'broken beyond repair' while now Intel engineers have sent out a new series looking to get it re-enabled. While Intel is normally quite good with their new hardware support being in good shape well ahead of launch, their new code for supporting the ENQCMD functionality for the Data Streaming Accelerator (DSA) with Xeon 'Sapphire Rapids' has been an exception.
