Re: [Qemu-devel] [PATCH v2 0/3] HMP/snapshot changes - do not use ID anymore

[Eric Blake]

On 1/9/19 11:38 AM, Max Reitz wrote:

>>>>> I do think it affects users of HMP, because right now you can delete
>>>>> snapshots with their ID, and after this series you cannot.
>>>>

>> This. Is. HMP.
>>
>> Not a stable ABI, no deprecation period of two releases.
> 
> Well, if you want to do it.
> 
> This may be HMP, but this is also the only interface to savevm, so it's
> not like users have a choice to use a more stable interface.  I know
> that was a conscious decision, more or less, but I don't see why we need
> to be so nasty when the hardest thing about doing a nice deprecation
> would be to remember to make it an error in half a year.

Indeed, and libvirt IS using 'savevm' via HMP via QMP's
human-monitor-command, since there is no QMP counterpart for internal
snapshot.  Even though lately we consistently tell people that internal
snapshots are underdeveloped and you should use external snapshots, it
does not get away from the fact that libvirt has been using 'savevm' to
drive internal snapshots for years now, and that we MUST consider
back-compat and/or add an introspectible QMP interface before making
changes that would break libvirt.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

signature.asc
Description: OpenPGP digital signature