Re: [Qemu-devel] [PATCH v2 1/4] sdbus: add a QMP command to access a SDBus

[Markus Armbruster <armbru@redhat.com>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Mon, 11 Mar 2019 at 13:43, Eduardo Habkost <ehabkost@redhat.com> wrote:
>>
>> On Mon, Mar 11, 2019 at 12:49:50PM +0100, Thomas Huth wrote:
>> > On 08/03/2019 17.11, Philippe Mathieu-Daudé wrote:
>> > > Hi Markus,
>> > >
>> > > [Asking again from the correct series thread]
>> > >
>> > > On 1/3/18 10:49 PM, Philippe Mathieu-Daudé wrote:
>> > >> Use Base64 to serialize the binary blobs in JSON.
>> > >> So far at most 512 bytes will be transfered, which result
>> > >> in a 684 bytes payload.
>> > >> Since this command is intented for qtesting, it is acceptable.
>> > >
>> > > Any comment regarding QMP for this patch?
>> >
>> > Is this useful for anybody else than qtest? If not, I think this should
>> > rather go into the qtest protocol instead, since QMP is our "public"
>> > protocol.
>>
>> Extending qtest requires writing parsers by hand.  Do we really
>> want to go that route and start extending the qtest protocol more
>> often?
>
> Perhaps we could have qtest-only QMP commands that only get
> recognized if qtest_enabled() ?

QMP commands are defined at compile time.  We just got rid of the hack
to "unrecognize" selected commands dynamically at run-time (commit
0b69f6f72ce), which we had because our compile-time facilities were
lacking.  I'd hate to bring this hack back.

What's easy is to have QMP commands that fail unless qtest_enabled() :)