thanks for the review!

Make hw.acpi.spmc.intel_dsm_revision sysctl operate directly on Intel DSM set struct.

Make sched_preempt_locked entirely responsible for releasing thread lock and style change.

looks good!

Don't ever use Microsoft DSM UUID for getting constraints, as this isn't supported (checked on Intel acpidump).

Comment about changing sc->constraint_count and more style(9) improvements.

Remove struct acpi_spmc_private and just set DSM set flags directly on softc + style(9) improvements.

See changes/comments in D48387, but will add an interface for PMC suspend and resume which this will use.

Which kind of interrupts do you still see that prevent staying in S0ix? I think you mentioned some IPIs at some point, but which ones? Can we determine their cause?

Remove SPMC callbacks on struct acpi_softc. I will replace them with new pmc_suspend and pmc_resume methods in another revision. This leaves the acpi_spmc_suspend and acpi_spmc_resume (renamed from acpi_spmc_enter/exit) functions unused at the moment. Lmk if this is okay or if you'd rather I add these in a different revision too.

fixed most of the issues highlighted. Will address the allocating-memory-in-probe-function pattern and add an interface for late suspend/early resume (or maybe call this something like pmc_enter and pmc_exit? then again maybe on some platforms the PMC isn't necessarily intended to be called after device suspend) in the future.

Fix issues pointed out by olce@ and apply some suggestions. Main changes:

Remove unused acpi_s2idle_looping

Don't use new IPI_IDLE/IPI_UNIDLE, but use smp_rendezvous_cpus() calling sched_do_idle() instead.

Can totally use smp_rendezvous_cpus() for this instead of adding 2 new IPIs. I thought I had run into a problem using rendezvous when I first implemented this, but I just tried it again and see no problem doing it this way.