On Feb 05 13:41:25, [email protected] wrote:
> On Sat, Feb 5, 2022 at 2:54 AM Jan Stary <[email protected]> wrote:
>
> > This is current/amd64 on a Thinkapd T420s, dmesgs below.
> > It seems that C2 is or is not supported depending on
> > whether the machine boots on AC or on battery
> > (judging by three boots of each).
> > Is this intended?
> >
>
> The acpicpu driver is reporting what ACPI told it; presumably the authors
> of the AML intended this change as a way to reduce power consumption.
>
> Now, ACPI provides a mechanism for the OS to tell it to notify the OS if
> the contents of the _CST table changes and at least in some cases
> acpicpu registers for that and if called it would write new acpicpu lines
> to the dmesg.
>
> If you're not seeing those when plugging/unplugging,
I don't.
> there are two
> possibilities:
> * does the AML on your system actually change the values and trigger the
> notify?
> * is acpicpu actually registering the callback correctly?
>
> I would suggest adding a printf() right before the aml_register_notify()
> call in acpicpu.c to see if it's actually being hit,
Probably not: I added a printf() right there
but nothing shows in dmesg when plugging/unpluging.
(yes, this is on the recompiled kernel with the printf)
Jan
> and if it is then dump
> the tables on your box and grovel around in them to see if you see
> notification support on the CPU nodes.
>
>
> Philip Guenther
>
