Messages in this thread | | | Date | Thu, 9 Jun 2022 16:05:20 +0530 | Subject | Re: [PATCH V5] arm64: perf: Make exporting of pmu events configurable | From | Srinivasarao Pathipati <> |
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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.
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. > > Will
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