Re: [Qemu-devel] [PATCH v4 00/11] convert savevm to use qapi and introduce qmp command

[Wenchao Xia]

于 2013-4-11 1:33, Pavel Hrdina 写道:
> On 10.4.2013 19:15, Eric Blake wrote:
> > On 04/10/2013 08:05 AM, Pavel Hrdina wrote:
> > > Here is another proposal how to handle vm snapshots:
> > >
> > > QMP vm-snapshot-save:
> > >      - { 'command': 'vm-snapshot-save',
> > >          'data': { 'name': 'str' },
> > >          'returns': 'SnapshotInfo' }
> > >      - vm-snapshot-save returns an error if there is an existing
> > >        snapshot with the same name
> > >      - you cannot provide an id for a new snapshot
> > >      - on success all information about created snapshot will be
> > > returned
> > >
> > > QMP vm-snapshot-load
> > >      - { 'command': 'vm-snapshot-load',
> > >          'data': { '*name': 'str', '*id': 'int' },
> > >          'returns': 'SnapshotInfo' }
> > >      - one of the name or id must be provided
> > >      - if both are provided they will match only the snapshot with the
> > >        same name and id
> > >      - returns SnapshotInfo only if the snapshot exists.
> > >
> > > QMP vm-snapshot-delete:
> > >      - { 'command': 'vm-snapshot-delete',
> > >          'data': { '*name': 'str', '*id': 'int' },
> > >          'returns': 'SnapshotInfo' }
> > >      - same rules as vm-snapshot-load
> >
> > Missing some form of query-snapshots to list all consistent snapshots
> > that can be loaded or deleted (or is that another series?)
>
> Yes, there is another series for that.
> http://lists.nongnu.org/archive/html/qemu-devel/2013-04/msg00196.html
>
> > Also, while load can only take a consistent snapshot, it might make
> > sense to expose two levels of delete - one that deletes consistent
> > snapshots, and one that deletes a snapshot for a given block device
> > regardless of whether it is consistent across all devices in use by
> > the VM.
>
> I think that Wenchao also works on it. He posted some patches for block
> snapshots about month ago.
  yep, the latest version is at
http://lists.nongnu.org/archive/html/qemu-devel/2013-04/msg02525.html
which expose block'image info to management stack. Luckily the two
serial does not conflict each other in main part:),  only for
bdrv_snapshot_find() function.

> > > HMP savevm:
> > >      - args_type = "force:-f,name:s?",
> > >      - if the name is not provided the HMP command will generates new
> > >        one for QMP command
> > >      - if there is already a snapshot with provided or generated name
> > >        it will fails
> > >      - there will be an optional -f parameter to force saving requested
> > >        snapshot and it will internally use vm-snapshot-delete and then
> > >        vm-snapshot-save
> > >      - all information about created snapshot will be printed
> > >
> > > HMP loadvm:
> > >      - args_type = "name:s?,id:i?",
> > >      - follow the same behavior as the QMP command
> >
> > Except that with HMP, arguments are positional.  You can't provide 'id'
> > in isolation; by listing id:i? second, the parser requires that the
> > first argument encountered is a name.
> >
> > I think a better interface might be:
> >
> > HMP loadvm:
> >      - args_type = "id:-i,name:s?'
> >
> > If just name is given, first do a tag lookup; if that fails do an id
> > lookup.  If the -i flag is given, skip the tag lookup just do an id
> > lookup.
>
> I didn't realize that, thanks for pointing this out.
>
> > > HMP delvm:
> > >      - args_type = "name:s?,id:i?"
> > >      - same rules as loadvm
> >
> > Same comment as for loadvm.


--
Best Regards

Wenchao Xia