Re: [PATCH v1 1/2] perf auxtrace: Add 'T' itrace option for timestamp trace

[Leo Yan <leo.yan@linaro.org>]

Hi Adrian,

On Tue, Nov 07, 2023 at 09:19:10AM +0200, Adrian Hunter wrote:
> On 6/11/23 23:52, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Oct 19, 2023 at 01:47:15PM +0300, Adrian Hunter escreveu:
> >> On 14/10/23 10:45, Leo Yan wrote:
> >>> An AUX trace can contain timestamp, but in some situations, the hardware
> >>> trace module (e.g. Arm CoreSight) cannot decide the traced timestamp is
> >>> the same source with CPU's time, thus the decoder can not use the
> >>> timestamp trace for samples.
> >>>
> >>> This patch introduces 'T' itrace option. If users know the platforms
> >>
> >> "If users know" <- how would users know?  Could the kernel
> >> or tools also figure it out?
> > 
> > Adrian, I'm trying to go all the outstanding patches, do you still have
> > any issues with this series?
> 
> No, although the question wasn't actually answered.  I presume users
> just have to try the 'T' option and see if it helps.

Sometimes, users are software developers in SoC companies, they can
know well for the hardware design but are confused why current
implementation cannot use timestamp trace.  This is the main reason
I sent this patch set.

An example hardware platform is DB410c [1], we know its CoreSight can
support timestamp trace, but if without this adding option 'T', we
have no chance to use it due to it its CPU arch is prior to Armv8.4.

@Arnaldo, since James gave comments in his replying, I will respin new
patch set and send out.  Thanks for popping up this patch set!

Leo

[1] https://developer.qualcomm.com/hardware/dragonboard-410c