Enable PID_IN_CONTEXTIDR by default when Arm SPE is enabled. This flag is required to get PID data in the SPE trace. Without it the perf tool will report 0 for PID which isn't very useful, especially when doing system wide profiling or profiling applications that fork.
There is a small performance overhead when enabling PID_IN_CONTEXTIDR, but SPE itself is optional and not enabled by default so the impact is minimised. Cc: Will Deacon <w...@kernel.org> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Al Grant <al.gr...@arm.com> Cc: Leo Yan <leo....@linaro.org> Cc: John Garry <john.ga...@huawei.com> Cc: Suzuki K Poulose <suzuki.poul...@arm.com> Cc: Mathieu Poirier <mathieu.poir...@linaro.org> Cc: Catalin Marinas <catalin.mari...@arm.com> Signed-off-by: James Clark <james.cl...@arm.com> --- arch/arm64/Kconfig.debug | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 265c4461031f..b030bb21a0bb 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -2,6 +2,7 @@ config PID_IN_CONTEXTIDR bool "Write the current PID to the CONTEXTIDR register" + default y if ARM_SPE_PMU help Enabling this option causes the kernel to write the current PID to the CONTEXTIDR register, at the expense of some additional -- 2.28.0