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

[Peter Lieven <pl@dlh.net>]

Jan Kiszka wrote:
> Juan Quintela wrote:
>   
>> Jan Kiszka <jan.kiszka@web.de> 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