Messages in this thread | | | Date | Thu, 9 Jun 2022 18:37:34 +0530 | Subject | Re: [PATCH V5] arm64: perf: Make exporting of pmu events configurable | From | Srinivasarao Pathipati <> |
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On 6/9/2022 5:02 PM, Will Deacon wrote: > [Please don't top-post] > > On Thu, Jun 09, 2022 at 04:05:20PM +0530, Srinivasarao Pathipati wrote: >> On 6/9/2022 3:32 PM, Will Deacon wrote: >>> On Mon, May 23, 2022 at 05:19:34PM +0530, Srinivasarao Pathipati wrote: >>>> The PMU export bit (PMCR_EL0.X) is getting reset during pmu reset, >>>> Make is configurable using sysctls to enable/disable at runtime. >>>> It can also be enabled at early bootup with kernel arguments. >>>> >>>> Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com> >>>> --- >>>> Changes since V4: >>>> - Registering sysctls dynamically for only arm64 as suggested by Will >>>> - Not removed the code to configure with kernel parameters >>>> as the sysctl's kernel parameter(sysctl.kernel.export_pmu_events) >>>> is not working at early bootup. pmu_reset() getting called before >>>> sysctl's kernel parameter is set. >>> Why do you need this during early bootup? Perf won't program any events >>> until much later and if somebody else is configuring the PMU before >>> entering Linux then they can also set that X bit in the PMCR. >> On our Qualcomm platforms, The X bit is getting set by firmware at early >> bootup for Qualcomm use cases >> and non-secure world is resetting it, that causing issue. > What "Qualcomm use cases" and why should we care about them upstream?
Thanks Will & Robin for your inputs .
Understood your point , pushed next version [V6] after removing kernel parameters code.
> > Will
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