Re: [Xen-devel] Linux 3.4 dom0 kernel error loading xen-acpi-processor: Input/output error

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Mar 18, 2013 at 04:20:51PM -0400, Konrad Rzeszutek Wilk wrote:
> > 
> > Hmm, on the R510 server where xen-acpi-processor doesn't work 
> > /sys/firmware/acpi/tables/dynamic/ is empty.. 
> 
> Pfff.. And 'cpuinfo' or 'cpufreq-info' when you boot baremetal gives
> you different P-states?
> 
> If so, is the DSDT different that when running under Xen? And
> lasty, does it create any SSDT in the dynamic directory?
>

Finally I figured this one out.. in the end it was a BIOS 
settings/configuration issue.

I found this: 
http://en.community.dell.com/techcenter/power-cooling/w/wiki/best-practices-in-power-management.aspx

So I had to enable "OS Control" for "Power Management" in the Dell server BIOS,
and after that the CPU P-states are available in the ACPI tables, 
and xen-acpi-processor driver loads and works OK in the dom0 kernel!

(I'm almost 100% certain I tried that option already earlier,
so I don't have any idea why it didn't work back then.. but *now* it seems to 
work!)

For reference I'm using Intel L5640 Xeon CPU, and here's xenpm output for it:

# xenpm get-cpufreq-states

cpu id               : 0
total P-states       : 7
usable P-states      : 7
current frequency    : 1596 MHz
P0         [2262 MHz]: transition [                   5]
                       residency  [                  59 ms]
P1         [2261 MHz]: transition [                   0]
                       residency  [                   0 ms]
P2         [2128 MHz]: transition [                   0]
                       residency  [                   0 ms]
P3         [1995 MHz]: transition [                   0]
                       residency  [                   0 ms]
P4         [1862 MHz]: transition [                   0]
                       residency  [                   0 ms]
P5         [1729 MHz]: transition [                   0]
                       residency  [                   0 ms]
*P6        [1596 MHz]: transition [                   5]
                       residency  [                3437 ms]

cpu id               : 1
total P-states       : 7
usable P-states      : 7
current frequency    : 1596 MHz
P0         [2262 MHz]: transition [                   4]
                       residency  [                 103 ms]
P1         [2261 MHz]: transition [                   0]
                       residency  [                   0 ms]
P2         [2128 MHz]: transition [                   0]
                       residency  [                   0 ms]
P3         [1995 MHz]: transition [                   0]
                       residency  [                   0 ms]
P4         [1862 MHz]: transition [                   0]
                       residency  [                   0 ms]
P5         [1729 MHz]: transition [                   0]
                       residency  [                   0 ms]
*P6        [1596 MHz]: transition [                   4]
                       residency  [                5893 ms]

.. and so on.


Thanks a lot Konrad for your help on this!


-- Pasi


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