xbzrle relies on reading pages that have already been sent
to the destination and then applying the modifications; we can't
do that in postcopy because the destination may well have
modified the page already or the page has been discarded.
I already didn't allow reception of xbzrle pages, but I
forgot to add the test to stop them being sent.
Enabling both xbzrle and postcopy can make some sense;
if you think that your migration might finish if you
have xbzrle, then when it doesn't complete you flick
over to postcopy and stop xbzrle'ing.
This corresponds to RH bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1368422
Symptom is:
Unknown combination of migration flags: 0x60 (postcopy mode)
(either 0x60 or 0x40)
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2ebeaec012