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SubjectRE: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequency from the hypervisor
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> -----Original Message-----
> From: Gleb Natapov [mailto:gleb@redhat.com]
> Sent: Tuesday, September 17, 2013 10:44 PM
> To: KY Srinivasan
> Cc: H. Peter Anvin; x86@kernel.org; gregkh@linuxfoundation.org; linux-
> kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de;
> apw@canonical.com; jasowang@redhat.com; tglx@linutronix.de;
> JBeulich@suse.com; bp@alien8.de
> Subject: Re: [PATCH V2 1/1] X86: Hyper-V: Get the local APIC timer frequency
> from the hypervisor
>
> On Tue, Sep 17, 2013 at 07:53:36PM +0000, KY Srinivasan wrote:
> > > > Thanks Gleb. Here is the link for the latest Hyper-V specification:
> > > > http://www.microsoft.com/en-us/download/details.aspx?id=39289
> > > >
> > > > This spec talks about how migration is handled with regards to TSC.
> > > >
> > > All I can see is "15.4.3 Partition Reference TSC Mechanism". I see
> > > nothing about HV_X64_MSR_TSC_FREQUENCY specifically. To access this MSR
> > > a partition needs AccessFrequencyMsrs privilege, may be partition that
> > > cab be migrated does not have this privilege?
> >
> > If you use the MSR to read the TSC frequency, then indeed when you migrate
> then there
> > is no guarantee that the TSC frequency won't change when you migrate. The
> approach
> > described in section 15.4.3 is the preferred approach that can accommodate
> migration.
> >
> Thanks.

Peter,
Please let me know if there are other issues I need to address here. Now that Dmitry has queued up the
Hyper-V keyboard driver, with this patch we can fully support Linux on our uefi firmware.

Regards,

K. Y


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