Re: [PATCH v3 3/3] intel_idle: Provide enter_dead() handler for SRF

[Rafael J. Wysocki]

On Tue, Nov 12, 2024 at 8:18 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> On Tue, Nov 12 2024 at 12:28, Rafael J. Wysocki wrote:
> > On Tue, Nov 12, 2024 at 12:18 PM Patryk Wlazlyn
> > <patryk.wlazlyn@xxxxxxxxxxxxxxx> wrote:
> >> I don't think so. The old algorithm gives fairly good heuristic for computing
> >> the mwait hint for the deepest cstate. Even though it's not guaranteed to work,
> >> it does work on most of the platforms that don't early return. I think we should
> >> leave it, but prefer idle_driver.
> >
> > IOW, as a fallback mechanism, it is as good as it gets.
> >
> > As the primary source of information though, not quite.
>
> So we have at least 5 places in the kernel which evaluate CPUID leaf 0x5
> in different ways.
>
> Can we please have _ONE_ function which evaluates the leaf correctly
> once and provides the required information for all places ready to use?

Yup, that's what needs to be done.