Re: NMI problems with Dell SMP Xeons

[Keith Owens]

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.

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