Re: [PATCH 4/8] ARM: etm: Allow range selection

From: Arve Hjønnevåg
Date: Tue Feb 15 2011 - 18:04:40 EST


On Tue, Feb 15, 2011 at 5:50 AM, Alexander Shishkin <virtuoso@xxxxxxxxx> wrote:
> On Mon, Feb 14, 2011 at 10:11:12PM -0800, Arve Hjønnevåg wrote:
>> Trace kernel text segment by default as before, allow tracing of other
>> ranges by writing a range to /sys/devices/etm/trace_range, or to trace
>> everything by writing 0 0.
>
> Since you're adding this, I think it might make sense to add a 3rd optional
> ctx id field, so that userspace tracing is also possible, especially when
> on-chip ETB sizes increase to something more sensible than what they are
> these days.
>

That might be useful, but I think it can be added later. My main
motivation for adding this is so we can turn off the filtering. We
want to use tracing in combination with a hardware watchdog to debug
hard lockups and we don't want any filtering in this case.

--
Arve Hjønnevåg
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