Re: [Xen-devel] kernel 3.7+ cpufreq regression on AMD system running as dom0

Jan Beulich
2013-01-14T16:55:43Z

>>> On 14.01.13 at 17:34, Borislav Petkov <bp@alien8.de> wrote:
> On Mon, Jan 14, 2013 at 04:58:54PM +0100, Stefan Bader wrote:
>> --- a/drivers/acpi/processor_perflib.c
>> +++ b/drivers/acpi/processor_perflib.c
>> @@ -340,6 +340,9 @@ static void amd_fixup_frequency(struct acpi_processor_px
> *px
>> if ((boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model < 10)
>> || boot_cpu_data.x86 == 0x11) {
>> rdmsr(MSR_AMD_PSTATE_DEF_BASE + index, lo, hi);
>> + /* Bit 63 indicates whether contents are valid */
>> + if (!(hi & 0x8000000))
>> + return;
>
> I don't think that's the right change - this is fixing baremetal so that
> it works on xen. And besides, this code was in powernow-k8 before so I'm
> wondering why did it work then.

Because the driver doesn't get loaded in that case?

Jan