Re: Catching NForce2 lockup with NMI watchdog

From: Mikael Pettersson
Date: Fri Dec 05 2003 - 02:42:10 EST

Jesse Allen writes:
> Hi,
> I have a NForce2 board and can easily reproduce a lockup with grep on an IDE
> hard disk at UDMA 100. The lockup occurs when both Local APIC + IO-APIC are
> enabled. It was suggested to me to use NMI watchdog to catch it. However, the
> NMI watchdog doesn't seem to work.
> When I set the kernel parameter "nmi_watchdog=1" I get this message in
> /var/log/syslog:
> Dec 4 20:10:30 tesore kernel: ..MP-BIOS bug: 8254 timer not connected to
> Dec 4 20:10:30 tesore kernel: timer doesn't work through the IO-APIC -
> disabling NMI Watchdog!
> "nmi_watchdog=2" seems to work at first, In /var/log/messages:
> Dec 4 20:13:11 tesore kernel: testing NMI watchdog ... OK.
> but it still locks up.

The NMI watchdog can only handle software lockups, since it relies on
the CPU, and for nmi_watchdog=1 the I/O-APIC + bus, still running.
Hardware lockups result in, well, hardware lockups :-(
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