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Failed to access PMCCNTR_EL0 on RK3399 Board

lsy2025

https://github.com/jerinjacobk/armv8_pmu_cycle_counter_el0

I got that  application in user-space can not access "PMCCNTR_EL0" commonly. So, I cross-compiled kernel-space code in github project above and insmod gennerated ko file on my rk3399 board.

However, I still could not access PMCCNTR_EL0 regsiter after that. I wonder that how could I fix it?

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  • 0 in reply to Stephen Theobald

    Thanks for your reply ! When I disable all core couidle like below

    for X in $(seq 0 3); do for Y in $(seq 1 6); do echo 1 > /sys/devices/system/cpu/cpu$X/cpuidle/state$Y/disable ; done ; done

    "asm volatile("mrs %0, pmccntr_el0" : "=r"(time_start))" will not lead to illegal instruction

    What I want to know is does PMCCNTR_EL0 register being shared with each cpu core and will increment it self if any cpu core active? If that, how should I use PMCCNTR_EL0 ?

Reply
  • 0 in reply to Stephen Theobald

    Thanks for your reply ! When I disable all core couidle like below

    for X in $(seq 0 3); do for Y in $(seq 1 6); do echo 1 > /sys/devices/system/cpu/cpu$X/cpuidle/state$Y/disable ; done ; done

    "asm volatile("mrs %0, pmccntr_el0" : "=r"(time_start))" will not lead to illegal instruction

    What I want to know is does PMCCNTR_EL0 register being shared with each cpu core and will increment it self if any cpu core active? If that, how should I use PMCCNTR_EL0 ?

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