[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: RE: RE: RE: [Xen-devel] No C-States any longer...
> From: Carsten Schiers [mailto:carsten@xxxxxxxxxx] > Sent: Wednesday, June 22, 2011 7:36 PM > > >> There is a comment in acpi_processor_get_power_info_default it is > >> said that all processors need to support C1 at least. So (hypothesis), > >> if my BIOS is not implemented as specified (neither _CST nor PBLK), > >>> shouldn't acpi_processor_get_power_info_default also bee called on my > >> machine? Is the code exiting too early? > > > >You can argue that point. It exits at current point because typical BIOS > >provide either CST or valid FADT/PBLK info. Of course even when ACPI > >table is broken we can still make a valid C1 entry. But also note that even > >then such ACPI Cstate information is not gathered, the kernel always > >invokes hlt when system is idle which achieves the effect. :-) > > After having had some discussion with Gigabyte, I am now sure that the BIOS > intentionally doesn't implement C-States at all. Gigabyte says, they > iomplemeted > Cool'n'Quiet "instead". great that this is clarified from the vendor. :-) > > In don't share this point, as I think Spec does require either _CST or PBLK. > Nevertheless, I think to remember that > > - xenpm did only mention C0 and C1 in the past > - but xenpm did so and does not any longer there're always various ACPI-incompatible boxes in the market, and the reason for the different behavior may come from the fact that newer kernel more conforms to the ACPI spec now. > > Eventually, even if it's only cosmetic, something needs to be changed in order > to reflect that case by setting up C1 in such a case. I am sorry, but I was > not > able to do it. I agree that from statistics p.o.v, C1/C0 should be always exposed regardless of whether ACPI is broken. Thanks Kevin _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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