> From: Dave Hansen [mailto:d...@sr71.net] > Sent: Wednesday, June 03, 2015 12:55 PM > To: LKML; Yu, Fenghua; John Stultz; the arch/x86 maintainers > Subject: hangs in verify_pmtmr_rate() > > I'm seeing boot hangs when trying to boot a 32-bit 4.1.0-rc5 kernel on some > 64-bit CPUs (I'm not sure if it is a regression). The NMI watchdog shows > init_acpi_pm_clocksource() as the last thing in the backtrace, specifically > verify_pmtmr_rate()'s I/O instructions. It appears to be mach_countup()'s > while loop that gets stuck. > > Booting with "pmtmr=0" works around this for me, as would unsetting > CONFIG_X86_PM_TIMER I'd imagine. > > The hardware I'm doing this on is a bit wonky and I think the hpet is broken > on it. > > Does this look like *really* broken hardware, or something that we should > be detecting and able to recover from?
Latest 4.1.0-rc5 defconfig boots fine without "pmtmr=0" on my machine which is same kind as Dave's. I always give "hpet=disable" on this machine to w/a a known hw issue. Thanks. -Fenghua
