Re: [Qemu-devel] [PATCH 16/18] qapi: Convert info snapshots

[Eric Blake]

On 08/15/2012 01:41 AM, Pavel Hrdina wrote:
> Signed-off-by: Pavel Hrdina <address@hidden>
> ---
>  hmp.c            | 33 +++++++++++++++++++++++++++++++++
>  hmp.h            |  1 +
>  monitor.c        |  2 +-
>  qapi-schema.json | 34 ++++++++++++++++++++++++++++++++++
>  qmp-commands.hx  | 30 ++++++++++++++++++++++++++++++
>  savevm.c         | 51 ++++++++++++++++++++++++---------------------------
>  sysemu.h         |  2 --
>  7 files changed, 123 insertions(+), 30 deletions(-)
> 

> @@ -1053,6 +1053,40 @@
>  { 'command': 'query-block-jobs', 'returns': ['BlockJobInfo'] }
>  
>  ##
> +# @SnapshotInfo:
> +#

We've got competition here:
https://lists.gnu.org/archive/html/qemu-devel/2012-08/msg02961.html

These two patches need to converge into a single design.

> +# Snapshot list.  This structure contains list of snapshots for virtual 
> machine.
> +#
> +# @id: id of the snapshot.
> +#
> +# @tag: human readable tag of the snapshot.
> +#
> +# @vm_size: size of the snapshot in Bytes.

As this is a new QMP command, you should use '-', not '_'.  Benoit's
patch named this @vm-state-size.

> +#
> +# @date: date and time of the snapshot as unix timestamp.
> +#
> +# @vm_clock: time in the guest in nsecs.

For online internal snapshots (those created by savevm), the vm clock
offset makes sense. But for offline snapshots (those created by
'qemu-img snapshot', with no VM state), there is no vm clock offset.
'qemu-img info' lists 00:00:00.000 as a result, but I wonder if it would
be better to leave this field (and vm-state-size) as #optional and omit
them from the JSON for offline snapshots.

And since qemu refuses to load offline snapshots, it might be worth an
additional field in the JSON that says whether a snapshot is online or
offline, to make it easier for the parsing application to determine
whether it can be loaded or must go through qemu-img while the guest is
offline (then again, keeping vm-state-size as non-optional, and checking
for 0 size, somewhat covers this).

> +#
> +# Since:  1.2

1.3 (entire series...)

-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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