From: Mike Leach <mike.leach@linaro.org>
To: James Clark <James.Clark@arm.com>
Cc: suzuki.poulose@arm.com, mathieu.poirier@linaro.org,
coresight@lists.linaro.org, leo.yan@linaro.com,
Leo Yan <leo.yan@linaro.org>, John Garry <john.garry@huawei.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v2 6/6] Documentation: coresight: Expand branch broadcast documentation
Date: Fri, 21 Jan 2022 12:50:34 +0000 [thread overview]
Message-ID: <CAJ9a7VihnvK6uwYri0kh_pwQu893+FrdcUNg0Y5iW7Euh3YwuA@mail.gmail.com> (raw)
In-Reply-To: <20220113091056.1297982-7-james.clark@arm.com>
On Thu, 13 Jan 2022 at 09:11, James Clark <james.clark@arm.com> wrote:
>
> Now that there is a way of enabling branch broadcast via perf, mention
> the possible use cases and known limitations.
>
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
> .../trace/coresight/coresight-etm4x-reference.rst | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/trace/coresight/coresight-etm4x-reference.rst b/Documentation/trace/coresight/coresight-etm4x-reference.rst
> index 0439b4006227..ec336575919c 100644
> --- a/Documentation/trace/coresight/coresight-etm4x-reference.rst
> +++ b/Documentation/trace/coresight/coresight-etm4x-reference.rst
> @@ -656,7 +656,15 @@ Bit assignments shown below:-
> ETM_MODE_BB
>
> **description:**
> - Set to enable branch broadcast if supported in hardware [IDR0].
> + Set to enable branch broadcast if supported in hardware [IDR0]. The primary use for this feature
> + is when code is patched dynamically at run time and the full program flow may not be able to be
> + reconstructed using only conditional branches.
> +
> + Choosing this option will result in a significant increase in the amount of trace generated -
> + possible danger of overflows, or fewer instructions covered. Note, that this option also
> + overrides any setting of :ref:`ETM_MODE_RETURNSTACK <coresight-return-stack>`, so where a branch
> + broadcast range overlaps a return stack range, return stacks will not be available for that
> + range.
>
> .. _coresight-cycle-accurate:
>
> --
> 2.28.0
>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK
next prev parent reply other threads:[~2022-01-21 12:50 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 9:10 [PATCH v2 0/6] coresight: Add config flag to enable branch broadcast James Clark
2022-01-13 9:10 ` [PATCH v2 1/6] " James Clark
2022-01-21 12:43 ` Mike Leach
2022-01-28 11:19 ` Suzuki K Poulose
2022-02-02 20:25 ` Mike Leach
2022-03-11 14:58 ` James Clark
2022-03-11 15:56 ` Mike Leach
2022-04-22 10:18 ` James Clark
2022-05-04 9:46 ` Suzuki K Poulose
2022-01-13 9:10 ` [PATCH v2 2/6] coresight: Fail to open with return stacks if they are unavailable James Clark
2022-01-21 12:42 ` Mike Leach
2022-01-28 11:24 ` Suzuki K Poulose
2022-03-11 14:52 ` James Clark
2022-03-11 15:53 ` Mike Leach
2022-04-22 10:09 ` James Clark
2022-01-13 9:10 ` [PATCH v2 3/6] perf cs-etm: Update deduction of TRCCONFIGR register for branch broadcast James Clark
2022-01-21 12:44 ` Mike Leach
2022-01-28 11:25 ` Suzuki K Poulose
2022-02-15 14:52 ` Arnaldo Carvalho de Melo
2022-01-13 9:10 ` [PATCH v2 4/6] Documentation: coresight: Turn numbered subsections into real subsections James Clark
2022-01-21 12:47 ` Mike Leach
2022-01-28 11:26 ` Suzuki K Poulose
2022-01-13 9:10 ` [PATCH v2 5/6] Documentation: coresight: Link config options to existing documentation James Clark
2022-01-21 12:49 ` Mike Leach
2022-01-13 9:10 ` [PATCH v2 6/6] Documentation: coresight: Expand branch broadcast documentation James Clark
2022-01-21 12:50 ` Mike Leach [this message]
2022-01-27 20:26 ` [PATCH v2 0/6] coresight: Add config flag to enable branch broadcast Mathieu Poirier
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