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RE: [Xen-devel] Guest TSC and Xen (Intel and AMD feedback please)

To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Xen-Devel (E-mail)" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Guest TSC and Xen (Intel and AMD feedback please)
From: "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>
Date: Fri, 4 Jul 2008 11:31:42 -0600
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> >Is this something that you (or Intel in general) could look at?
> >I would be happy to participate but I don't think I understand
> >VT well enough.  Once the trap occurs, I suppose Xen system time
> >could be used as the virtual TSC, possibly scaled up.
> >
>
> There should be tiny related to VT, as only turning on some bit to
> allow RDTSC trapping and then the rest stuff should be common
> how to handle it. We'll take a look, but can't commit the time due
> to other scheduled bandwidth. But if you'd like to jump in early
> we definitely can help with VT side.

If you can post a patch with code that:

1) declares a boolean global variable: softtsc = 0
2) if the variable is set, a rdtsc instruction in any hvm
   domain causes a trap
3) the trap handler just does a physical rdtsc and returns

then I could probably take it from there.

Dan
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