Re: [PATCH 4/4] xen: Always set the vram dirty during migration.

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

On Tue, 17 Jul 2012, Stefano Stabellini wrote:
> On Tue, 17 Jul 2012, Anthony PERARD wrote:
> > Because the call to track the dirty bit in the video ram during migration won't
> > work (it returns -1), we set dirtybit on the all video ram.
> > 
> > Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> > ---
> >  xen-all.c |    5 +++++
> >  1 files changed, 5 insertions(+), 0 deletions(-)
> > 
> > diff --git a/xen-all.c b/xen-all.c
> > index 498883b..00bdb50 100644
> > --- a/xen-all.c
> > +++ b/xen-all.c
> > @@ -502,6 +502,11 @@ static void xen_sync_dirty_bitmap(XenIOState *state,
> >          return;
> >      }
> >  
> > +    if (unlikely(xen_in_migration)) {
> > +        /* track_dirty_vram does not work during migration */
> > +        memory_region_set_dirty(framebuffer, 0, size);
> > +        return;
> > +    }
> >      rc = xc_hvm_track_dirty_vram(xen_xc, xen_domid,
> >                                   start_addr >> TARGET_PAGE_BITS, npages,
> >                                   bitmap);
> 
> Why are you setting the entire framebuffer dirty?
> We should set dirty only the actualy region that is supposed to be
> dirty.
> 

Also memory_region_set_dirty calls cpu_physical_memory_set_dirty_range,
in which you didn't add a call to xen_modified_memory.