Commit 2ebeaec0 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Juan Quintela
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Postcopy vs xbzrle: Don't send xbzrle pages once in postcopy [for 2.8] 

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: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 091ecc8b

migration/ram.c

+3 −1
Original line number Diff line number Diff line
@@ -771,7 +771,9 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus *pss, 
             * page would be stale

             */

            xbzrle_cache_zero_page(current_addr);

        } else if (!ram_bulk_stage && migrate_use_xbzrle()) {

        } else if (!ram_bulk_stage &&

                   !migration_in_postcopy(migrate_get_current()) &&

                   migrate_use_xbzrle()) {

            pages = save_xbzrle_page(f, &p, current_addr, block,

                                     offset, last_stage, bytes_transferred);

            if (!last_stage) {