Re: [Xen-devel] [PATCH] tools/firmware: remove "_PS0/3" Method

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sun, 2011-12-04 at 04:38 +0000, Hao, Xudong wrote:
> > Have you tested any other OSes? How does Windows for example respond to
> > this change in the ACPI tables?
> > 
> 
> Yes, I did some test with this patch, till now, all result shows patch
> works well with PCI device assign and hotplug, as well as HVM S3.
> 
> Pass cases:
> RHEL6.1, SLES11 SP1, Win2008 VF device assign and hotplug.
> RHEL6.1, Winxp, Win7 e1000e NIC device assign and hotplug
> RHEL6.1, RHEL5.1 Guest S3
> 
> > Are there any devices which do not implement PCI PM and therefore rely on
> > this ACPI mechanism to function? My understanding was that
> > 47e9037ac166 was required in part due to the lack of PCI PM support on some
> > VF devices. I think it was a different Intel SR-IOV NIC than the one you are
> > testing, an 82559 if [0] is to be believed.
> > 
> VF is such device which do not have PCI PM capability, these device
> will be set PCI_D0 directly in function
> pci_platform_power_transition().
> 
> static int pci_platform_power_transition(struct pci_dev *dev, pci_power_t 
> state)
> {
>     int error;
>     if (platform_pci_power_manageable(dev)) {
>         error = platform_pci_set_power_state(dev, state);
>         ...
>     } else {
>         error = -ENODEV;
>         /* Fall back to PCI_D0 if native PM is not supported */
>         if (!dev->pm_cap)
>             dev->current_state = PCI_D0;
> 
> > Also there was a previous attempt to remove _PS0 in [1]. Allen Kay (CCd) 
> > tested
> > and reported that removing these values causes Windows not to boot. It was
> > suggested in that thread that both _PS0 and _PS3 need to be removed (which
> > you do) but it was also suggested that doing so breaks Linux S3 support, 
> > have
> > you tried this?
> > 
> Windows does not to boot only happen when remove _PS0, however Windows
> guest can boot up with removing _PS0 and _PS3.
> 
> According to the annotate of "_PS0/3", it's for debug purpose. I do
> not know whether it's required for other purpose, comments of others?

Your explanation / results are good enough for me.

Thanks, Ian.



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