Re: NMI problems with Dell SMP Xeons

[Andi Kleen]

On Wednesday 07 June 2006 13:47, Keith Owens wrote:
> Andi Kleen (on Wed, 7 Jun 2006 10:01:40 +0200) wrote:
> >
> >>
> >> Two ways:
> >>
> >> (1) Boot with a kernel with CONFIG_ACPI=n, so the OS only finds 2 cpus
> >>     in the MPT instead of the 4 listed by ACPI.
> >>
> >> (2) The kernel has ACPI=y, but is booted with maxcpus=2.
> >>
> >> In both cases, send_IPI_allbutself() with IPI 2 or an NMI will result
> >> in a hard reset.
> >
> >Sounds both like a "Don't do that when it hurts" . I know some people
> >have religious issues with ACPI, but it's simple a fact that many
> >modern boxes don't work correctly in obvious or subtle ways without it. 
> 
> Building a kernel without ACPI is silly nowadays.  But even with ACPI,
> booting with a restricted maxcpus and sending IPI 2 or NMI as broadcast
> will kill these boxes.  maxcpus is a valid option.

Yes, I'm not opposed to using *_sequence on cpu_online_map here. Please send a patch.

-Andi
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