Re: [PATCH 1/6] Enable pvclock flags in vcpu_time_info structure

From: Glauber Costa
Date: Mon Apr 26 2010 - 14:45:21 EST


On Mon, Apr 26, 2010 at 11:11:57AM -0700, Jeremy Fitzhardinge wrote:
> On 04/26/2010 10:46 AM, Glauber Costa wrote:
> > This patch removes one padding byte and transform it into a flags
> > field. New versions of guests using pvclock will query these flags
> > upon each read.
> >
>
> Is this necessary? Why not just make the pvclock driver maintain a
> local flag set, and have the HV backend call into it to update it. Why
> does it need to be part of the pvclock structure?
Because it is already there, and we have plenty of space left?

There are obvious other ways, but I don't see any of them being simpler.
If we go by the method you suggested, we'd have, for instance, to register
the memory area where this flags lives. Which is a duplication of the
infrastructure already present in kvmclock.


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