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