Re: [Qemu-devel] [PATCH v2] trace: [qmp] Add QAPI/QMP commands to query and control event tracing state

[Markus Armbruster]

Lluís Vilanova <address@hidden> writes:

> Markus Armbruster writes:
>
>> Lluís Vilanova <address@hidden> writes:
>>> Markus Armbruster writes:
>>> 
>>>> Lluís Vilanova <address@hidden> writes:
>>>>> Also removes old "trace-event", "trace-file" and "info trace-events" HMP
>>>>> commands.
>>> 
>>>> We gain the ability to control trace via QMP, but lose the ability to
>>>> control it via HMP, correct?
>>> 
>>> Right. I can keep the HMP commands, but doing so requires exposing
>>> the internal
>>> trace event identifier number in the QMP interface. Also,
>>> "trace-file" cannot be
>>> implemented on top of the current QMP commands, and is specific to
>>> the "simple"
>>> tracing backend.
>
>> Would rough feature-parity with QMP be feasible with new HMP commands on
>> top of the QMP interfaces, completely ignoring HMP backward
>> compatibility?
>
> Except for "trace-file", it would be quite easy, yes.

Yes, please!

>                                                       For "trace-file", we can
> either keep the current HMP implementation, or add new QMP commands to support
> it (I'd rather devote my time to something else, though).

trace-file is only available with CONFIG_TRACE_SIMPLE.  Losing it would
be tolerable, I guess.  But I'd keep it as is until its maintenance
becomes a burden.