Re: nmi_watchdog default setting on i386 and x86_64

From: Andi Kleen
Date: Tue May 23 2006 - 10:37:30 EST

Mikael Pettersson <mikpe@xxxxxxxxx> writes:

> Mike Mason writes:
> > Does anybody know the reasoning behind having nmi_watchdog turned off by
> > default on i386 and on by default on x86_64. I've heard that i386 had
> > problems with false positives in the past, but that local apic watchdog
> > may make that concern obsolete.
> On i386 the problems are mainly hardware and BIOS. In particular,
> lots of Dell laptops have capable hardware but broken BIOSen that
> hang the machines if we try to enable anything sending performance
> counter interrupts via the local APIC.

AFAIK that trouble was mostly when you forced the local APIC on against
the wishes of the BIOS. That was always a dumb idea and gladly
Linux doesn't try that by default anymore.


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