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    SubjectRe: [PATCH 13/17] coresight etr: Do not clean ETR trace buffer
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    On 03/11/17 20:17, Mathieu Poirier wrote:
    > On 3 November 2017 at 04:10, Suzuki K Poulose <Suzuki.Poulose@arm.com> wrote:
    >> On 02/11/17 20:36, Mathieu Poirier wrote:
    >>>
    >>> On Thu, Oct 19, 2017 at 06:15:49PM +0100, Suzuki K Poulose wrote:
    >>>>
    >>>> We zero out the entire trace buffer used for ETR before it
    >>>> is enabled, for helping with debugging. Since we could be
    >>>> restoring a session in perf mode, this could destroy the data.
    >>>
    >>>
    >>> I'm not sure to follow you with "... restoring a session in perf mode
    >>> ...".
    >>> When operating from the perf interface all the memory allocated for a
    >>> session is
    >>> cleanup after, there is no re-using of memory as in sysFS.
    >>
    >>
    >> We could directly use the perf ring buffer for the ETR. In that case, the
    >> perf
    >> ring buffer could contain trace data collected from the previous "schedule"
    >> which the userspace hasn't collected yet. So, doing a memset here would
    >> destroy that data.
    >
    > I originally thought your comment was about re-using the memory from a
    > previous trace session, hence the confusion. Please rework your
    > changelog to include this clarification as I am sure other people can
    > be mislead.

    Sure, will do.

    Thanks
    Suzuki

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