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Subject: Re: [PATCH 3/4] tracing: Allow mmio tracer to display
 trace_printk() and other events
From: Steven Rostedt <rostedt@goodmis.org>
Reply-To: rostedt@goodmis.org
To: Pekka Paalanen <pq@iki.fi>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Larry Finger <Larry.Finger@lwfinger.net>
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Date: Thu, 13 May 2010 15:42:41 -0400
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On Thu, 2010-05-13 at 11:11 -0400, Steven Rostedt wrote:

> > > How does that sound?
> > 
> > That would be fine. Is it not redundant with what you said in
> > your first sentence?
> > 
> 
> Right now with this patch as is. When you enable the mmiotracer it
> clears the ring buffer. But if someone previously enabled an event (like
> sched_switch for example) then that event will appear in the output of
> the tracer.
> 
> The user will need to disable that event and restart the mmiotracer so
> the output will not break the userspace tools. Is this OK?
> 
> If not, then my suggestion is to have an mmiotracer option that keeps it
> from printing out any event except for the ones it knows about.
> 
> The reason I added this patch in the first place was because Larry
> Finger was using the mmiotrace with trace_printk() and the current code
> does not print out the trace_printk() when mmiotracer is active.

Pekka,

Are you OK with this version of the patch or do you want me to add the
option as described above?

-- Steve