From: Chase Venters <chase.venters@clientec.com>
To: Rene Herman <rene.herman@keyaccess.nl>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.17-rc3 -- SMP alternatives: switching to UP code
Date: Tue, 9 May 2006 20:55:01 -0500 [thread overview]
Message-ID: <200605092055.23265.chase.venters@clientec.com> (raw)
In-Reply-To: <4461341B.7050602@keyaccess.nl>
On Tuesday 09 May 2006 19:29, Rene Herman wrote:
> Hi list.
>
> I just noticed this in the 2.6.17-rc3 dmesg:
>
> ===
> Checking 'hlt' instruction... OK.
> SMP alternatives: switching to UP code
> Freeing SMP alternatives: 0k freed
> ACPI: setting ELCR to 0400 (from 1608)
> ===
>
> Should I be seeing this "SMP alternatives" thing on a !CONFIG_SMP
> kernel? It does say 0k, but something is apparently being done at
> runtime still. Why?
This is part of a recent patch by Gerd Hoffmann:
>> Implement SMP alternatives, i.e. switching at runtime between different
>> code versions for UP and SMP. The code can patch both SMP->UP and UP->SMP.
>> The UP->SMP case is useful for CPU hotplug.
An explicit test of the smp variable (not CONFIG_SMP macro) exists in this
code. I missed the discussion about this patch, but it appears from reading
the patch notes that the behavior is intentional. More information can be
found in the git and lkml archives.
> Rene.
Thanks,
Chase
next prev parent reply other threads:[~2006-05-10 1:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-10 0:30 2.6.17-rc3 -- SMP alternatives: switching to UP code Rene Herman
2006-05-10 1:55 ` Chase Venters [this message]
2006-05-10 9:28 ` Gerd Hoffmann
2006-05-10 11:41 ` Rene Herman
2006-05-11 12:13 ` [patch] SMP alternatives: skip with UP kernels Gerd Hoffmann
2006-05-11 21:07 ` Rene Herman
2006-05-12 11:41 ` Gerd Hoffmann
2006-05-15 21:41 ` Rene Herman
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