linux-kernel - Re: [PATCH] Resurect proper handling of maxcpus= kernel option

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Date:	Wed, 06 Aug 2008 13:23:31 -0700
From:	Max Krasnyansky <maxk@...lcomm.com>
To:	unlisted-recipients:; (no To-header on input)
CC:	mingo@...e.hu, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, lizf@...fujitsu.com,
	jeff.chua.linux@...il.com
Subject: Re: [PATCH] Resurect proper handling of maxcpus= kernel option

> From: Max Krasnyansky <maxk@...lcomm.com>
> 
> For some reason we had redundant parsers registered for maxcpus=. 
> One in init/main.c and another in arch/x86/smpboot.c
> So I nuked the one in arch/x86.
> 
> Also 64-bit kernels used to handle maxcpus= as documented in
> Documentation/cpu-hotplug.txt. CPUs with 'id > maxcpus' are initialized
> but not booted. 32-bit version for some reason ignored them even though
> all the infrastructure for booting them later is there.
> 
> In the current mainline both 64 and 32 bit versions are broken. I'm
> too lazy to look through git history but I'm guessing it happened as
> part of the i386 and x86_64 unification.
> 
> This patch restores the correct behaviour. I've tested x86_64 version on
> 4- and 8- way Core2 and 2-way Opteron based machines. Various config
> combinations SMP, !SMP, CPU_HOTPLUG, !CPU_HOTPLUG.
> Booted with maxcpus=1 and maxcpus=4, etc. Everything is working as expected.
> 
> I cannot test 32-bit version (no 32-bit machines here).
> 
> Signed-off-by: Max Krasnyansky <maxk@...lcomm.com>
> Cc: lizf@...fujitsu.com
> Cc: jeff.chua.linux@...il.com

I just realized that I managed to screw up my From: email address in 
git-send-email command line. Please reply to maxk@...lcomm.com.

Max
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