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

["Carsten Schiers" <carsten@xxxxxxxxxx>]

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

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

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).

Carsten.


-----Ursprüngliche Nachricht-----
Von: Tian, Kevin [mailto:kevin.tian@xxxxxxxxx] 
Gesendet: Freitag, 10. Juni 2011 10:49
An: Carsten Schiers; xen-devel
Betreff: RE: RE: RE: [Xen-devel] No C-States any longer...

> From: Carsten Schiers [mailto:carsten@xxxxxxxxxx]
> Sent: Friday, June 10, 2011 3:09 AM
> 
> Through some adding of printk I was able at least to verify that for 
my
> 3 core CPU AMD Athlon X3 400e
> 
>   - xen_px_notifier is called six times
>   - Hypervisor is reporting XEN_PM_PX is called six times
>   - Hypervisor is never reporting XEN_PM_CX to have been called
>   - this is because xen_cx_notifier is never called.
>   -> set_cx_pminfo is never called.
> 
> What I will try to find out next is to check where xen_cx_notifier
> *should* be called. OS debugging is
> not realy my expertise, let's see whether you first can give me a hint
> or whether I am quicker to find
> it on my own.
> 

the entry point in dom0 looks like:

xen_acpi_processor_start
        xen_acpi_processor_power_init
                processor_cntl_xen_notify
                        xen_ops.pm_ops
                                xen_cx_notifier
                                        HYPERVISOR_dom0_op

Thanks
Kevin



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