[libvirt] [PATCH 3/3] qemu: hyperv: Add support for reference time couter enlightenment

Daniel P. Berrange berrange at redhat.com
Fri Feb 7 14:03:31 UTC 2014


On Fri, Feb 07, 2014 at 02:58:19PM +0100, Peter Krempa wrote:
> On 02/07/14 12:03, Paolo Bonzini wrote:
> > Il 05/02/2014 12:02, Peter Krempa ha scritto:
> >> Add a new <timer> for the HyperV reference time counter enlightenment
> >> for Windows guests.
> >>
> >> This feature provides a paravirtual approach to track timer events for
> >> the quest (similar to kvmclock).
> > 
> > RTC can be confusing because the same acronym expands to both "real-time
> > clock" and "reference time counter".
> 
> I was confused too, when I saw it the first time.
> 
> > 
> > By the way, the same <timer> will drive two things: the reference time
> > counter, and the reference TSC page.  In current kernels, the reference
> > TSC page just tells the guest "use the reference time counter", but this
> > can be changed in the future without breaking the guest ABI.
> 
> That's right, the feature is actually backwards compatible to a great
> extent and even tolerates the iTSC vanishing at migration. This makes
> our lives really easier.
> 
> > 
> > So, what about naming it hv_clock or hyperv_clock or hyperv_ref?
> 
> hyperv_clock then. DanPB was concerned that hv could mean "hypervisor"
> to some people.

If we go for consistency with 'kvmclock', then we might as well
remove the underscore too eg  'hypervclock'

Daniel
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