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From:   Lei Wen <adrian.wenl@gmail.com>
Date:   Sat, 8 Dec 2018 20:04:50 +0800
Message-ID: <CALZhoSRaR-eMyr7HKUTDi5oRiJfRZ7x1NRRM49v-nn6U7e9sJg@mail.gmail.com>
Subject: Coresight etmv4 enable over 32bit kernel
To:     mathieu.poirier@linaro.org
Cc:     linux-kernel@vger.kernel.org,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        leiwen@outlook.com
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Hi Mathieu,

I am enabling etmv4 coresight over one Cortex-A7 soc, using 32bit kernel.
And I am following [1] to do experiment regarding the addr_range feature.
The default addr_range is set as _stext~_etext, and it works fine with
etb as sink,
and etm as source. I could see there are valid kernel addresses using OpenCSD.

But while I try to store one small range of address pair, which contain only one
kernel function. It doesn't behavior like what said in [1], the write
pointer would
grows rapidly with the read pointer. And I dump the etb buffer and parse it with
openCSD, finding that there is no I_ASYNC packet in the dump and is fulled with
I_NOT_SYNC.

So my question is why ETB continue to grow when there is no trigger at all?
Is it normal? I could provide more info if you need it.

[1]: https://wiki.linaro.org/WorklingGroups/Kernel/Coresight/traceDecodingWithDS5

Thanks,
Lei