* Amit Shah (amit.s...@redhat.com) wrote: > On (Tue) 23 Feb 2016 [15:02:58], Jason Wang wrote: > > >> This means that 2.5 cannot migrate 2.4 virtual machines, right? Is that > > >> something we want to rectify in 2.6 by making e1000-82540em an alias of > > >> e1000 (instead of the other way round)? > > > You're right; I misread it. With that commit (8304402033): > > > > > > 2.4 with e1000-82540em will not migrate to 2.5 with e1000-82540em. > > > > > > This is despite they're aliased (so the cmdline is backward > > > compatible), but the migration device name actually changed. > > > > > > Of course, 2.5->2.4 will also not work. > > > > > > Since 2.4 emits 'e1000-82540em' as the device name in the migration > > > stream, and 2.5 emits just 'e1000', we have two different names for > > > the same device in two versions. > > > > > > To fix this, we'll need a hack on the dest side to allow e1000 and > > > e1000-82540em in the migration stream for the device, and this can be > > > done for 2.6 and 2.5.stable. > > > > > > Jason, can you attempt this? > > > > > Sure, but just need to understand the "problem". If I understand this > > correctly, the issue only happen for JSON description at the end of > > migration stream, and it won't break migration in fact? > > No, this does break migration. > > The stream contained 'e1000-82540em' as the section header for the > device earlier. It now only has 'e1000'. So a newer qemu will only > accept 'e1000', but not 'e1000-82540em' (from an older release).
OK, so do we need to get this fixed for 2.6 - i.e. now. Dave > > Amit -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
