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To: smp@freebsd.org
Cc: yokota@zodiac.mech.utsunomiya-u.ac.jp
Subject: Re: How to distinguish the SMP kernel and the UP kernel 
In-reply-to: Your message of "Wed, 03 Oct 2001 12:30:31 MST."
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References: <200110030310.MAA13836@zodiac.mech.utsunomiya-u.ac.jp>  <3BBB6757.9A668E99@mindspring.com> 
Date: Thu, 04 Oct 2001 21:11:30 +0900
From: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp>
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# moved to smp ML, to which this thread should have been posted
# in the first place :-)

>Kazutaka YOKOTA wrote:
>> 
>> Is there any way for the loadable module to detect if
>> the kernel is configured for SMP or UP?
>
>There is a global variable, "ncpu".  Its name may have changed
>recently, so you will want to look at the SYSCTL() stuff in
>/sys/i386/i386 to be sure.
>
>-- Terry

The sysctl variable hw.ncpu returns 1 in the UP kernel,
and returns the number of active CPUs in the SMP kernel.

When hw.ncpu == 1, it doesn't necessarily signifies the kernel
is configured for UP. Because it is perfectly permissible
to run the SMP kernel on the multi-CPU motherboard with only one
CPU installed...

Am I wrong?

Kazu

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