Re: Lockups - lost interrupt

Andrea Arcangeli (andrea@suse.de)
Mon, 13 Sep 1999 22:23:05 +0200 (CEST)


On Mon, 13 Sep 1999, Wade Hampton wrote:

>I tried twice on IRQ 0, but never got the OOPS. I tried on IRQ 3

While you are running with the IRQ zero as NMI source, try a `cat
/proc/interrupts`, you should get NMI irqs and you should also get timer
interrupt _only_ on the CPU0 marked as XT (8259) source of irqs. If you
get both NMI and the timer irqs then the NMI-watchdog should work
correctly on your hardware.

If it's working correctly and you get no-oops on the screen, then probably
the local-apic irq is still running on the CPUs. NOTE: the NMI oopser can
help _only_ if at least one CPU is lockedup with irq _disabled_. If the
irqs are enabled in both CPU then the NMI won't do nothing. In such case
you don't need the NMI patch but you only need to enable the SYSRQ keys in
the kernel configuration and then press SYSRQ+P at lockup time to get the
interesting debugging information out of the kernel. You should write on
paper the EIP addresses you'll get from SYSRQ+P. I am not sure if you just
tried the SYSRQ+P approch (I supposed so because you was just using the
NMI code).

Andrea

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