From: "Manuel Bouyer" <bouyer@antioche.eu.org>

> On Tue, Mar 15, 2005 at 11:32:22AM -0800, Jason Thorpe wrote:
> >
> > On Mar 15, 2005, at 11:14 AM, Manuel Bouyer wrote:
> >
> > >Most probably. But as I don't know exactly what MTRR is, I can't be
> > >sure :)
> >
> > Memory Type Range Register, if I remember correctly.  Allows you to set
> > caching attributes, etc. for memory ranges.
>
> OK. So it may need hypervisor calls, and also physical address
> convertions.
> It should not be too hard to fix.

Xen virtualizes MTRRs, see arch/xen/i386/kernel/cpu/mtrr/main.c in
linux-2.6.*-xen-sparse for how to use the interface (ADD, DEL, READ, use
READ until it fails to find out how many registers you can set...).

    christian