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SubjectRe: [PATCH v1 3/3] perf cs-etm: Remove callback cs_etm_find_snapshot()
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On 28/05/2021 17:15, Leo Yan wrote:
> The callback cs_etm_find_snapshot() is invoked for snapshot mode, its
> main purpose is to find the correct AUX trace data and returns "head"
> and "old" (we can call "old" as "old head") to the caller, the caller
> __auxtrace_mmap__read() uses these two pointers to decide the AUX trace
> data size.
>
> cs_etm_find_snapshot() should be removed with below reasons:

Hi Leo,

I came across this other comment in coresight-tmc-etr.c that should probably
be fixed up if we remove cs_etm_find_snapshot(). The same is duplicated in a
few other files:

/*
* In snapshot mode we simply increment the head by the number of byte
* that were written. User space function cs_etm_find_snapshot() will
* figure out how many bytes to get from the AUX buffer based on the
* position of the head.
*/
if (etr_perf->snapshot)
handle->head += size;

I'm still reviewing patch 1 and 2 as well.

James

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