Re: [PATCH v8 0/8] hmp, qmp: Add commands to introspect virtio devices

[Markus Armbruster <armbru@redhat.com>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> On Wed, Oct 27, 2021 at 07:41:41AM -0400, Jonah Palmer wrote:
>> This series introduces new QMP/HMP commands to dump the status of a
>> virtio device at different levels.
>> 
>> [Jonah: Rebasing previous patchset from Oct. 5 (v7). Original patches
>>  are from Laurent Vivier from May 2020.
>> 
>>  Rebase from v7 to v8 includes an additional assert to make sure
>>  we're not returning NULL in virtio_id_to_name(). Rebase also
>>  includes minor additions/edits to qapi/virtio.json.]
>> 
>> 1. Main command
>> 
>> HMP Only:
>> 
>>     virtio [subcommand]
>> 
>>     Example:
>> 
>>         List all sub-commands:
>> 
>>         (qemu) virtio
>>         virtio query  -- List all available virtio devices
>>         virtio status path -- Display status of a given virtio device
>>         virtio queue-status path queue -- Display status of a given virtio queue
>>         virtio vhost-queue-status path queue -- Display status of a given vhost queue
>>         virtio queue-element path queue [index] -- Display element of a given virtio queue
>
> I don't see a compelling reason why these are setup as sub-commands
> under a new "virtio" top level. This HMP approach and the QMP 'x-debug-query'
> naming just feels needlessly different from the current QEMU practices.
>
> IMHO they should just be "info" subcommands for HMP. ie
>
>          info virtio  -- List all available virtio devices
>          info virtio-status path -- Display status of a given virtio device
>          info virtio-queue-status path queue -- Display status of a given virtio queue
>          info virtio-vhost-queue-status path queue -- Display status of a given vhost queue
>          info virtio-queue-element path queue [index] -- Display element of a given virtio queue

I agree with Dan (but I'm not the maintainer).

> While the corresponding QMP commands ought to be
>
>          x-query-virtio
>          x-query-virtio-status
>          x-query-virtio-queue-status
>          x-query-virtio-vhost-queue-status
>          x-query-virtio-queue-element

I agree with Dan (and I am the maintainer).

The x- is not strictly required anymore (see commit a3c45b3e62 'qapi:
New special feature flag "unstable"').  I lean towards keeping it here,
because we don't plan to stabilize these commands.