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