linux-kernel - Re: Dual cores on Core2Duo not detected?

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Date:	Mon, 13 Nov 2006 15:00:39 +0100
From:	"Jesper Juhl" <jesper.juhl@...il.com>
To:	"Shaun Q" <shaun@...hink.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Dual cores on Core2Duo not detected?

On 13/11/06, Shaun Q <shaun@...hink.com> wrote:
> Hi there everyone --
>
> I'm trying to build a custom kernel for using both cores of my new
> Core2Duo E6600 processor...
>
> I thought this was simply a matter of enabling the SMP support in the
> kernel .config and recompiling, but when the kernel comes back up, still
> only one core is detected.
>
> With the default vanilla text-based SuSE 10.1 install, it does find both
> cores...
>
> Anyone have any pointers for me on what I might be missing?
>

This is probably not your problem, but it could be, so worth checking.
Are you booting with  maxcpus=1  on your kernel commandline?

Another thing could be that you need to set CONFIG_NR_CPUS to
something more than 2. at least in the past some people observed that
depending on hov CPUs/cores got numbered CONFIG_NR_CPUS needed to be
set at least as high as the highest numbered core. Try setting it to 8
and see if that makes a difference.

On a related note; you probably also want to enable CONFIG_SCHED_MC in
addition to just SMP support.

-- 
Jesper Juhl <jesper.juhl@...il.com>
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