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RE: [Xen-devel] [PATCH] replace rdtsc emulation-vs-native xen boot optio

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH] replace rdtsc emulation-vs-native xen boot option with per-domain (hypervisor part)
From: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Date: Thu, 5 Nov 2009 09:08:58 -0800 (PST)
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Xen-Devel \(E-mail\)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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> On 06/10/2009 14:49, "Dan Magenheimer" 
> <dan.magenheimer@xxxxxxxxxx> wrote:
> > This was intended to record the offset across migration.
> > But a per-domain stime offset must already be recorded
> > somewhere else, or hvm fully-emulated platform timers
> > would be broken across migration.
> > 
> > Do pv guests need something similar or is it magically
> > handled someplace that I couldn't quickly find?
> PV guests understand that there will be a system-time 
> discontinuity across
> save/restore. All I did was remove an unused field. You can 
> reintro it when
> you use it.

Finally got back to looking at this...

For an HVM, the relevant time values are saved/restored
as part of the cpu state.

For a PV, I'm thinking about adding them to the
domctl_getdomaininfo struct rather than add additional
domctls for each.  Is this the proper place or will
changes to this struct result in backward compatibility
problems or ??


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