On Tue, 2016-04-26 at 12:42 +0000, Vineet Gupta wrote: On Friday 22 April 2016 06:56 PM, Lada Trimasova wrote: I think what we have now is sufficient - but u seem to want a prettier failure output. Anyhow, this print is coming from util/evsel.c: perf_evsel__open_strerror() At the very least you want another entry in switch case for ENOTSUPP and then check if event was sampling one ( evsel->attr.sample_period) - use that as a hint for saying sampling events not supported. ENOTSUPP is not visible for user programs. So it's impossible to add this entry to mentioned switch. I think that there is no good way to make error message more understandable without breaking existing api. But this will print the same even if CONFIG_PERF_EVENTS=n. To really fix this you would want to change the error code returned by SYSCALL_DEFINE5(perf_event_open for PERF_PMU_CAP_NO_INTERRUPT to say -EOPNOTSUPP and use the sample_period to say this was for samplign events! However this is an ABI change and might not be acceptable as some existing scripts etc might break. /bin/dmesg may provide additional information. No CONFIG_PERF_EVENTS=y kernel support configured? --------------------------------->8----------------------------------- As you can see the root cause of this error message is not obvious. CONFIG_PERF_EVENTS is selected but still there's a problem while existing suggestion barely makes any sense. So probably there could be a way to determine if CONFIG_PERF_EVENTS was selected or not. I am not sure about the correct way of solving this problem. Maybe I should add some checks of syscalls return values and give user a warning when not PMU interrupts are available. Any suggestions are appreciated. Regards, Lada Trimasova. _______________________________________________ linux-snps-arc mailing list linux-snps-arc at lists.infradead.org<mailto:linux-snps-arc at lists.infradead.org> http://lists.infradead.org/mailman/listinfo/linux-snps-arc Regards, Lada.
