Re: [Qemu-devel] Re: Qemu-KVM Livate Migration 0.12.2 -> 0.12.3/4 broken?

[Peter Lieven]

Jan Kiszka wrote:
> Juan Quintela wrote:
>   
> > Jan Kiszka <address@hidden> wrote:
> >     
> > > Juan Quintela wrote:
> > >       
> > > > Lack of "proper" subsections.  IDE is something like:
> > > >
> > > > const VMStateDescription vmstate_ide_drive = {
> > > >     .version_id = 4,
> > > > ....
> > > > }
> > > >
> > > > static const VMStateDescription vmstate_bmdma = {
> > > >     .name = "ide bmdma",
> > > >     .version_id = 4,
> > > > ...
> > > > }
> > > >
> > > > const VMStateDescription vmstate_ide_pci = {
> > > >     .name = "ide",
> > > >     .version_id = 4,
> > > > ....
> > > >         VMSTATE_STRUCT_ARRAY(bmdma, PCIIDEState, 2, 0,
> > > >                      vmstate_bmdma, BMDMAState),
> > > >         VMSTATE_IDE_DRIVES(bus[0].ifs, PCIIDEState),
> > > >         VMSTATE_IDE_DRIVES(bus[1].ifs, PCIIDEState),
> > > > ....
> > > > }
> > > >
> > > >
> > > > Notice that everything is at version 4.  It used to be everything at
> > > > version 3.  Now the problem is that when migrating from v3 -> v4.  We
> > > > put in one place v3, But we only have a version number at the toplevel,
> > > > rest of "subsections" don't sent a version number.  There is no way to
> > > > fix it in the general case.  We can hack something around for ide, but
> > > > that will just be a hack, or we can backport marcelo change and port it
> > > > as a proper subsection (that is my plan).  I expect to have time at the
> > > > end of next time to work on this.
> > > >         
> > > BTW, the IDE subsystem is yet lacking a proper vmstate section split-up
> > > along qdev boundaries (ie. vmstate_ide_pci should not contain drive
> > > structures). Do you plan to address this as well?
> > >       
> > Not for Friday, and not for 0.12.
> >     
>
> For sure. I missed that this was only a 0.12 issue.
>
>   
> > That is 0.13 material, and have to get one agreement on how to go.
> > We can go for:
> > - good structure
> > - backward compatibility
> >
> > I can't see any good way to get both at this stage :(  But I am open to
> > sugestions.
> >     
>
> Based on recent experiments with vmstate to enhance the hpet, I'm fairly
> optimistic that we can have both (just the code complexity suffers a
> bit): Split up the drive sections for new versions, but keep the legacy
> fields with attached .field_exists() filters for reading of old
> versions. But I may also underestimate issues of this particular case.
>
>   
> > Later, Juan.
> >
> > PD. BTW, very good work with printing the vmstate, that was one of the goals
> >     when we added it, that was the next step after porting everything to
> >     vmstate :)
> >
> >     
>
> I'm sorry for stealing you the pleasure to add it. :)
>
> Jan
>
>   
whats the status of this issue? will migration from 0.12.2 to 
0.12.4.1/0.13 work again?

whats the scheduled release dates for 0.12.4.1 and 0.13 (still july 1st) ?

thanks,
peter