Linux 5.9 Brings More IBM POWER10 Support, New/Faster SCV System Call ABI

With Linux 5.8 there is initial support for booting POWER10 CPUs while with Linux 5.9 there is more POWER10 work underway. Additionally, Linux 5.9 is bringing support for the newer and faster system call ABI for POWER9 and newer with the SCV instruction.

Linux 5.9 has "support for a new faster system call ABI using the scv instruction on Power9 or later." That is the recently covered work on POWER System Call Vectored (SCV). Using SCV can utilize faster registers and reducing machine specific register updates among other benefits for existing POWER9 CPUs and future POWER10 hardware.

Besides SCV, the other interesting POWER work for Linux 5.9 is focused on forthcoming POWER10 hardware. On the POWER10 front there is PMU (Power Monitoring Unit) support, dropping the mmap/mprotect PROT_SAO flag as it's unsupported there, and other fixes.

More details on all the POWER CPU architecture changes for Linux 5.9 via this mailing list post. POWER10 CPUs are to be manufactured on a 7nm process, utilize POWER ISA 3.1, the latest I/O and memory capabilities, and a variety of other improvements. POWER10 processors were expected to launch this year though it's looking increasingly like we won't be seeing much in the way of IBM/OpenPOWER POWER10 hardware until next calendar year. At least the open-source/Linux POWER10 enablement work continues happening well in recent months and most of the support looks like it should get ironed out in 2020.