Re: [Qemu-devel] [Qemu-block] Making QMP 'block-job-cancel' transactionable

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 04/04/2017 08:28 AM, Kashyap Chamarthy wrote:
>
>>> Minor or not, it is a useful viewpoint. Either way, as long as the new
>>> way of getting a transactional non-pivot successful completion is
>>> something that libvirt can learn via introspection, 
>> 
>> Can you elaborate a little more on the above, for my own edification --
>> how might it be possible for "libvirt can learn via introspection"?  Is
>> it via some method using the QMP 'query-commands' /
>> 'query-command-line-options'?
>
> Those, and query-qmp-schema.

Avoid query-command-line-options if you can.  If you can't, know its
limitations and quirks.

>                               If the change includes the addition of
> something new in the .json files describing QMP, then query-qmp-schema
> will let libvirt probe whether the version of qemu it it talking to has
> that new field or not (presumably, in this case it would be a new
> optional bool member to select the mode when creating a job, as well as
> a new command visible through query-commands to change the mode of a
> running job).