Decoding the PTM traces

[Arun KS]

Hello Punit,

On Wed, Nov 14, 2012 at 8:28 PM, Punit Agrawal <punit.agrawal at arm.com> wrote:
> Hi Arun,
>
> You can think of the trace in the ETB as the raw stream resulting from
> the multiplexing of different trace streams. So to get to the PTM trace
> you'll first have to de-multiplex the stream, and then decode the stream
> based on the source - in this case PTM.
>
> The format of the data stored in the ETB is described in the ETM TRM
> Section 9.6
> (http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0314h/Bgbhhidd.html).
> The decoding should give you a trace stream for each active trace
> source. The ATBID can be used to de-multiplex multiple sources, e.g.,
> the two PTMs associated with the two A9s.
>
> The PTM stream can then be decoded using the Program Flow Trace Protocol
> described in Program Flow Trace Architecture Specification Section 4
> (http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ihi0035b/Chddbbdf.html).

So do you mean that there is no open source tool which decodes this as
of now and I have to write one?

>
> Out of curiosity, may I ask what are you trying to do?

The main intention is to debug freeze issues using PTM traces.
When a device is in freeze, my intention is to  collect PTM traces
from ETB and decode.
So that I ll get traces of last few branches and exceptions.

Thanks,
Arun

>
> Hope this helps. Feel free to ask for clarification.
>
> Cheers,
> Punit
>
>
>
>
> On 14/11/12 14:04, Arun KS wrote:
>>
>> Hello,
>>
>> I m trying to capture and decode PTM trace from Cortex A9 dual core.
>>
>> I m successful  in configuring the driver(arch/arm/kernel/etm.c) and
>> setting the funnel to get data in ETB.
>> But I don't know how to decode these traces.
>>
>> Anyone has any pointers?
>>
>> Thanks,
>> Arun
>>
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>>
>
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