Hi, On Sat, Jan 09, 2016 at 04:13:48PM -0800, Mario Smarduch wrote: > I'm trying to get HARDLOCKUP detector to work on arm (on foundation > model and Juno, but armv7 should have the same issue). Turns out there is no > PERF NMI support (HAVE_PERF_EVENTS_NMI), which I guess would be PMU NMI - I > tested overflow on cycle counter and PMU interrupts can be masked. HARDLOCKUP > assumes perf interrupts are non-maskable and uses the PMU to program an NMI to > detect hard lockup and that in turn drives softlockup detection. > > Is there something, someplace in ARM manuals that addresses this, searched the > manuals but couldn't find anything? > > Or other approaches that I'm not aware off or have floated on the mailing list. Russell and Daniel did some work [1,2] to use FIQs as NMIs on arm, for backtracing and PMU overflow. For arm64 the kernel always runs on the non-secure side, so we don't expect to have access to FIQ. It's possible to implement NMIs using priorities (which it looks like Daniel was looking into [3]). Thanks, Mark. [1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/353795/ [2] http://www.linaro.org/blog/core-dump/debugging-arm-kernels-using-nmifiq/ [3] https://git.linaro.org/people/daniel.thompson/linux.git/shortlog/refs/heads/dev/arm64_nmi-v5 -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
