AW: RE: RE: RE: RE: [Xen-devel] No C-States any longer...

["Carsten Schiers" <carsten@xxxxxxxxxx>]

There are some information in FACP (attached), there is no FADT.

In order to test native Linux, I need some more days. Family & Barbecue 
have higher Prio ;o).

Carsten.

-----Ursprüngliche Nachricht-----
Von: Tian, Kevin [mailto:kevin.tian@xxxxxxxxx] 
Gesendet: Sonntag, 12. Juni 2011 10:57
An: Carsten Schiers; xen-devel
Betreff: RE: RE: RE: RE: [Xen-devel] No C-States any longer...

> From: Carsten Schiers [mailto:carsten@xxxxxxxxxx]
> Sent: Friday, June 10, 2011 10:56 PM
> 
> Some in-between notes, if someone is better in analyzing the code. 
There
> is the following sequence
> In drivers/scpi/processor_idle.c:
> 
>         result = acpi_processor_get_power_info_cst(pr);
> 
>         if (result == -ENODEV)
>                 result = acpi_processor_get_power_info_fadt(pr);
> 
>         if (result)
>                 return result;
> 
>         acpi_processor_get_power_info_default(pr);
> 
> On a working Intel machine, it will go through it like this:
> 
>   - acpi_processor_get_power_info_cst, which returns 0
>   - acpi_processor_get_power_info_default
>   - later acpi_processor_power_verify will find some c-states

this is expected sequence

> 
> On my non-working AMD machine, it will go through like this:
>   - acpi_processor_get_power_info_cst, which returns -ENODEV
>   - acpi_processor_get_power_info_fadt, which also return -ENODEV
>   - this result is returned

though CST is optional, it's weird that even FADT doesn't contain valid 
Cx
information. Could you compare with your working pvops dom0 version or
compare with generic linux to see any difference? This parse logic 
should
be generic for both Linux and Xen.

> 
> The returned result -ENODEV is cascaded up to the call in
> xen_acpi_processor_power_init, but there
> nothing is checked or done.
> 
> I will now try to find the root cause 
(acpi_processor_get_power_info_cst
> is to be checked next).

Anyway, you seems close to the root cause...
Thanks
Kevin

FACP.dsl
Description: Binary data

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