AW: RE: RE: RE: RE: RE: [Xen-devel] No C-States any longer...(it's not over!)

[Carsten Schiers <carsten@xxxxxxxxxx>]

I thought by buying a new mainboard, I could solve the issue. It is not the 
case.

>> >In your case there's no _CST found, and then no PBLK found.
>...
>w/o PBLK, FADT info is incomplete to construct a full Cstate information.

The new mainboard now implements a PBLK for the first CPU in FADT, but 
latencies for C2/C3 
are > 100/1000, which is the semantic to disable it (I read). 

But no change in xenpm output, there are still no C-States. 

I think acpi_processor_get_power_info_default is called too late. In old, 
working 2.6.18 code, 
a similar function acpi_processor_get_power_info_default_c1 is called as very 
first function in 
acpi_processor_get_power_info, to setup C1 which is mandatory for all CPUs.

Some other thoughts where I see the code needs changes:

  - even if spec says that either PBLK or _CST should implement, C1 should be 
set up (solves issue with mainboard 1)
  - when C2/C3 are above limits (100/1000), C1 still should be set up (solves 
issue with mainboard 2)
  - Spec allows PBLK for one CPU only (definition as of mainboard 2, I don't 
think code is respecting this case).

BTW:

  - I have C1E support in CPU and BIOS, but see no difference in DSDT and FADT 
when on/off in BIOS
  - Just curious: how many C-States should AMD X3 400e normally support? Why is 
my BIOS switching off C2/C3?

Carsten.

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