On Mon, Feb 13, 2012 at 10:16:00AM -0800, Yinghai Lu wrote: > On Mon, Feb 13, 2012 at 8:51 AM, Yinghai Lu <yinghai at kernel.org> wrote: > >> So I suspect we have a bug in our apic initialization somewhere, but > >> apic initialization should happen after printk are enabled. ?Or at least > >> after early printks so the reset YH is reporting doesn't make much sense. > > > > will try Don's first version patch that only removing disable_IO_APIC. > > first version patch (only removing disable_IO_APIC) is working. So I think I figured it out. I went through and commented out code in disable_local_APIC until I narrowed it down to the piece of code that needs to be disabled for it to work. Surprise, surprise... its LVTPC or perf! :-) Actually it is the nmi_watchdog which uses perf. My theory is NMIs are not disabled and one is generated by the local apic during decompression (just bad timing) and *splat*. Yinghai, you can probably prove this by echo 0 > /proc/sys/kernel/nmi_watchdog then do your kdump crash test. At least that test worked for me. So either we explicitly shutdown perf or just mask off LVTPC in a modified disable_local_APIC? Eric, thoughts, preferences? Cheers, Don
