From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: linux-kernel@vger.kernel.org, hpa@zytor.com
Subject: Re: [regression 2.6.27.10 & 2.6.28] \"nolapic\" option causes \"nosmp\"?
Date: Mon, 5 Jan 2009 22:07:25 +0000 (GMT) [thread overview]
Message-ID: <alpine.LFD.1.10.0901052156460.10676@ftp.linux-mips.org> (raw)
In-Reply-To: <200901050318.n053Iu0L068557@www262.sakura.ne.jp>
On Mon, 5 Jan 2009, Tetsuo Handa wrote:
> Adding "nolapic" option to kernel command line causes /proc/cpuinfo to show
> only 1 CPU, while the machine has 2 CPUs and the kernel was compiled with
> CONFIG_SMP=y.
>
> Something is wrong with CPU recognition/initialization code?
This is correct behaviour. The hardware uses the local APIC to
communicate between CPUs. With the subsystem disabled there is no way to
reach secondary CPUs on a standard x86 system.
> This topic is continued from http://lkml.org/lkml/2008/12/30/104 .
> I confirmed that this problem occurs on native Ubuntu 8.04 (i386) and
> native CentOS 5.2 (x86_64) on ThinkPad X60 (Core 2 Duo).
>
> Kernel 2.6.26.8 seems to be OK.
If this is the case, then "nolapic" must have been dysfunctional in that
version of the kernel.
Maciej
next prev parent reply other threads:[~2009-01-05 22:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-05 3:18 Tetsuo Handa
2009-01-05 22:07 ` Maciej W. Rozycki [this message]
2009-01-06 2:06 ` Tetsuo Handa
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