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From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [RFC PATCH v2 2/2] add support for Hyper-V invariant TSC
Date: Fri, 24 May 2013 16:41:24 -0300
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Cc: Gleb Natapov <gleb@redhat.com>, kvm@vger.kernel.org, pl@dlh.net
To: Vadim Rozenfeld <vrozenfe@redhat.com>
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On Fri, May 24, 2013 at 06:11:16AM -0400, Vadim Rozenfeld wrote:
> > Is there a better option?
> > 
> If setting TscSequence to zero makes Windows fall back to the MSR this is a
> better option.
> 
> +1 
> This is why MS has two different mechanisms:
> iTSC as a primary, reference counters as a fall-back.

Ok, is it documented that transition

iTSC valid (Sequence != 0 and != 0xFFFFFFFF) -> 
iTSC not valid but ref MSR valid (Sequence = 0), 

is a valid transition?

It was not obvious for me. Can you point to documentation?