On Wed, 26 Apr 2017 11:34:04 -0300 Eduardo Habkost <ehabk...@redhat.com> wrote:
> On Tue, Apr 25, 2017 at 05:37:50PM +0200, Igor Mammedov wrote: > > Since 2.7 commit (b2a575a Add optionrom compatible with fw_cfg DMA version) > > regressed migration during firmware exection time by > > abusing fwcfg.dma_enabled property to decide loading > > dma version of option rom AND by mistake disabling DMA > > for 2.6 and earlier globally instead of only for option rom. > > > > so 2.6 machine type guest is broken when it already runs > > firmware in DMA mode but migrated to qemu-2.7(pc-2.6) > > at that time; > > > > a) qemu-2.6:pc2.6 (fwcfg.dma=on,firmware=dma,oprom=ioport) > > b) qemu-2.7:pc2.6 (fwcfg.dma=off,firmware=ioport,oprom=ioport) > > > > to: a b > > from > > a OK FAIL > > b OK OK > > > > So we currently have broken forward migration from > > qemu-2.6 to qemu-2.[789] that however could be fixed > > for 2.10 by re-enabling DMA for 2.[56] machine types > > and allowing dma capable option rom only since 2.7. > > As result qemu should end up with: > > > > c) qemu-2.10:pc2.6 (fwcfg.dma=on,firmware=dma,oprom=ioport) > > > > to: a b c > > from > > a OK FAIL OK > > b OK OK OK > > c OK FAIL OK > > > > where forward migration from qemu-2.6 to qemu-2.10 should > > work again leaving only qemu-2.[789]:pc-2.6 broken. > > > > Reported-by: Eduardo Habkost <ehabk...@redhat.com> > > Analyzed-by: Laszlo Ersek <ler...@redhat.com> > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > > Reviewed-by: Laszlo Ersek <ler...@redhat.com> > > Reviewed-by: Eduardo Habkost <ehabk...@redhat.com> Marcel or Michael, could you pick up and merge the patch through your tree?
