Re: [RFC PATCH v4 5/8] x86/smp native_play_dead: Prefer cpuidle_play_dead() over mwait_play_dead()

[Rafael J. Wysocki]

On Tue, Nov 26, 2024 at 12:56 PM Patryk Wlazlyn
<patryk.wlazlyn@xxxxxxxxxxxxxxx> wrote:
>
> >>> If you first make intel_idle provide :enter_dead() for all CPUs on all
> >>> platforms and implement it by calling mwait_play_dead_with_hint(), you
> >>> won't need mwait_play_dead() any more.
> >> Crossed my mind, but because mwait_play_dead doesn't filter on Intel
> >> vendor specifically,
> >
> > In practice, it does.
> >
> > The vendor check in it is equivalent to "if Intel".
>
> Actually, what about INTEL_IDLE=n?
> We might hit acpi_idle, which would call mwait_play_dead_with_hint() now, but
> if we don't, don't we want to try mwait_play_dead before hlt or is it too
> unrealistic to happen?

In that case the hint to use would not be known anyway, so
hlt_play_dead() is the right choice IMV.