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From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Greg KH <gregkh@linuxfoundation.org>, a.p.zijlstra@chello.nl,
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Subject: Re: [RFC PATCH 01/20] coresight: etm3x: splitting 'etm_enable_hw()' operations
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Date: Fri, 02 Oct 2015 07:40:39 +0300
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Mathieu Poirier <mathieu.poirier@linaro.org> writes:

> On 30 September 2015 at 03:58, Alexander Shishkin
> <alexander.shishkin@linux.intel.com> wrote:
>> Most of these things can also be bypassed, as at least initially perf
>> events won't be using trigger/sequencer configurations, so we could
>> simply clear all these things out when a first perf event is created
>> (which would also disallow any sysfs poking around the etm/etb) and not
>> worry about them in the pmu callbacks.
>
> I don't want to restrain configuration options to what is available
> through Perf's cmd line.  The sysFS interface is there to complement
> what is currently not available.

In practice this means that part of your trace configuration will be
global and part -- per event, which can indeed work if you only have one
event at a time, but again, makes using perf infrastructure redundant
for this driver. For multiple events this doesn't make much sense.

Regards,
--
Alex