On Tue, May 21, 2013 at 10:16:48PM +0100, Peter Maydell wrote: > On 21 May 2013 21:43, mdroth <mdr...@linux.vnet.ibm.com> wrote: > > Makes sense, but apparently version IDs for incoming device state are > > not allowed to exceed the destination's version, so we can't bump it > > beyond the value in 1.5 without breaking migration from 1.5+ -> 1.5 > > We care about backwards migration? That sounds like a pain.
As a best effort at least, hence subsections and whatnot, but not always. This case for instance... > > > So I think our only option for version ID is to lock in the 1.5 value, > > which seems to be 1936 (hopefully that's consistent across builds...). > > Yeah, I'm not convinced that's going to be consistent across builds, > compilers, 64 vs 32 bit, etc etc etc. That's why I suggested a really > high number. Yah, it's more important to ensure old->new. Playing guessing games about struct sizes to try to maintain new->old is likely to conflict with that, so I guess we don't have much choice here. I'll send a patch out shortly. > > thanks > -- PMM >