* Jason Wang (jasow...@redhat.com) wrote: > > > On 2018年03月29日 16:08, Dr. David Alan Gilbert wrote: > > * Jason Wang (jasow...@redhat.com) wrote: > > > > > > On 2018年03月29日 00:36, Dr. David Alan Gilbert (git) wrote: > > > > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > > > > > > > When we're using the subsection we migrate both > > > > the 'props' and 'tso_props' data; when we're not using > > > > the subsection (to migrate to 2.11 or old machine types) we've > > > > got to choose what to migrate in the main structure. > > > > > > > > If we're using the subsection migrate 'props' in the main structure. > > > > If we're not using the subsection then migrate the last one > > > > that changed, which gives behaviour similar to the old behaviour. > > > > > > > > > > > But only after migration. Why not simply switch back to the old behavior > > > if > > > migrate_tso_props if false? > > Because: > > 1) We know it's a broken behaviour so it's better not to unfix it > > 2) The fix doesn't change guest visible behaviour other than actually > > sending the right packets; so there's no reason to make the fix > > itself dependent on the machine type. > > 3) Gating the fix itself on the flag is actually more complex and > > would need checking the flag in lots of places that are already > > pretty complex, rather than what this does which is just check it > > in one place at migration. > > It looks to me it was just something like: > > struct e1000x_txd_props *props = tp->cptse && chkflag(TSO) ? > &tp->tso_props : &tp->props;
is that the only thing that would change? > Btw, did this patch work when: > > migrate A to B > migrate B to C > > But there's no tx during B? Hmm, good question; I only tried it keeping the stream alive during migration. Lets see what happens. For this code to be used we have to be running with an old machine type/property. That means A->B will have either come from 2.11 or a 2.12 with this same patch. But given patch 2 that duplicates on loading; that means A->B should end up with B having the same data in both sets of props, and thus it doesn't matter which set this patch picks. Dave > Thanks > > > > > Dave > > > Thanks > > > > > -- > > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK > > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
