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RE: [Xen-devel] Error restoring DomU when using GPLPV

> On 04/08/2009 11:40, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
wrote:
> 
> >> Oh yes, there is no direct opposite of add_to_physmap... But I
think
> >> decrease_reservation will work okay in this case, fortunately.
> >>
> >
> > Given that I'm not going to use the grant table subsequent to
unmapping
> > them I'll probably get away with it, but does
> > XENMEM_decrease_reservation actually tell xen that the pages are no
> > longer actually part of the grant table?
> 
> No, for a xenheap page the page won't actually get freed. Xen keeps a
> reference to them until the domain is finally destroyed.
> 
> Regarding the Linux PV-on-HVM drivers - they may have the same issue.
Full
> PV guests do not as they have a gnttab_suspend() function called
during
> suspend callback (and for subtle reasons xc_domain_save can detect and
not
> save Xenheap pages for a full PV guests anyway - because it can see
the P2M
> table in that case).
> 
> Like I said before -- unmapping the gnttab pages I think will not help
you
> for live migration, but I suppose it is a reasonable thing to do
anyway. For
> live migration I think xc_domain_save needs t get a bit smarter about
> Xenheap pages in HVM guests.
> 

Understood. Do you have any idea about why it worked fine under 3.3.x
but not 3.4.x?

Thanks

James


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