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From: Markus Armbruster <armbru@redhat.com>
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Date: Thu, 21 Aug 2014 09:14:47 +0200
In-Reply-To: <87fvgrj6zo.fsf@fimbulvetr.bsc.es> (=?utf-8?Q?=22Llu=C3=ADs?=
	Vilanova"'s message of "Wed, 20 Aug 2014 21:28:27 +0200")
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Subject: Re: [Qemu-devel] [PATCH v2] trace: [qmp] Add QAPI/QMP commands to
	query and control event tracing state
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To: qemu-devel@nongnu.org
Cc: Stefan Hajnoczi <stefanha@redhat.com>, Luiz Capitulino <lcapitulino@redhat.com>

Llu=C3=ADs Vilanova <vilanova@ac.upc.edu> writes:

> Markus Armbruster writes:
>
>> Llu=C3=ADs Vilanova <vilanova@ac.upc.edu> writes:
>>> Markus Armbruster writes:
>>>=20
>>>> Llu=C3=ADs Vilanova <vilanova@ac.upc.edu> writes:
>>>>> Also removes old "trace-event", "trace-file" and "info trace-events" =
HMP
>>>>> commands.
>>>=20
>>>> We gain the ability to control trace via QMP, but lose the ability to
>>>> control it via HMP, correct?
>>>=20
>>> 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", w=
e can
> either keep the current HMP implementation, or add new QMP commands to su=
pport
> 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.