Re: More than 8 CPUs detected and CONFIG_X86_PC cannot handle it on2.6.16-rc6

From: Krzysztof Oledzki
Date: Sun Mar 12 2006 - 08:07:21 EST




On Sun, 12 Mar 2006, Andrew Morton wrote:

Krzysztof Oledzki <olel@xxxxxx> wrote:

On Sat, 11 Mar 2006, Andrew Morton wrote:

> Krzysztof Oledzki <olel@xxxxxx> wrote:
>>
>> After upgrading to 2.6.16-rc6 I noticed this strange message:
>>
>> More than 8 CPUs detected and CONFIG_X86_PC cannot handle it.
>> Use CONFIG_X86_GENERICARCH or CONFIG_X86_BIGSMP.
>>
>> This is a Dell PowerEdge SC1425 with two P4 Xeons with HT enabled (so with
>> totoal of 4 logical CPUs).
>
> Please send full dmesg output for the failing kernel, thanks.
Attached.

> Which is the most-recently-tested kernel which behaved correctly?
2.6.15.6

OK, thanks. I assume the machine's working OK?

Yes. So far no problems, only this warning.

From my reading, you have CONFIG_HOTPLUG_CPU enabled and the machine has an
APIC.
That is correct.

I'd expect that lots of people would hit that warning but for some
reason they don't - possibly because most APICs don't have sufficiently
high version numbers?

Anyway, various people cc'ed. I _think_ it's harmless, although the way in
which def_to_bigsmp propagates into the DMI and APIC code might be a
problem, depending upon config options.

Certainly the warning is incorrect, but I'm not sure what is the best thing
to do about it?

OK. Thank you.

Best regards,

Krzysztof Olędzki