Re: nmi_watchdog default setting on i386 and x86_64

[Andi Kleen]

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.

-Andi

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