On Sun, Sep 11, 2005 at 10:38:03AM -0700, Chuck Silvers wrote:
> hi,
> 
> what's wrong with just mapping the page twice in domain0?

It seems that the hypervisor doesn't allow multiple mappings in this case.
Either multiple mappings in the same domain (one remplacing the other)
or mapping of the page in both domain0 and the guest.
The Xen doc isn't clear about this, at several place it's implied that
the page must be unmapped from domain0 before the I/O is ack'd to the
guest. So even if multiple mappings work, I need to keep track of which
request use which pages, to ack the requests only once the no mappings
remain.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--