linux-kernel - [PATCH] fix maxcpus=N parsing

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Message-ID: <Pine.LNX.4.64.0708271554570.21853@blonde.wat.veritas.com>
Date:	Mon, 27 Aug 2007 16:02:12 +0100 (BST)
From:	Hugh Dickins <hugh@...itas.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Len Brown <len.brown@...el.com>, Andi Kleen <ak@...e.de>,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] fix maxcpus=N parsing

Fix 61ec7567db103d537329b0db9a887db570431ff4: maxcpus=N is now having no
effect on x86_64, and freezing bootup on i386 (because of inconsistency
with the separate maxcpus parsing down in arch/i386, I guess).  That's
because early_param parsing is a little different from __setup parsing,
and needs the "=" omitted: then it seems to work as the original commit
intended (no mention of IO-APIC in /proc/interrupts when maxcpus=0).

Signed-off-by: Hugh Dickins <hugh@...itas.com>
---
Sorry, I noticed this back in -mm, but got diverted by deeper mysteries.
Cc'ed Rusty: I presume there's a good reason why early_param parsing is
confusingly different, but he may know better and want to change it.

It's odd that i386 treats maxcpus=N differently from other architectures:
on i386 it limits cpu_possible_map, on others it just limits what boots
(then powersaved is liable to bring up the others on x86_64 - hmmm).

--- 2.6.23-rc3-git10/init/main.c	2007-08-26 18:10:20.000000000 +0100
+++ linux/init/main.c	2007-08-26 18:59:16.000000000 +0100
@@ -168,7 +168,7 @@ static int __init maxcpus(char *str)
 	return 0;
 }

-early_param("maxcpus=", maxcpus);
+early_param("maxcpus", maxcpus);
 #else
 #define max_cpus NR_CPUS
 #endif
-
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