linux-kernel - [tip:x86/urgent] x86: more than 8 32-bit CPUs requires X86

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Date:	Wed, 22 Apr 2009 02:36:45 GMT
From:	"tip-bot for Michael K. Johnson" <johnsonm@...th.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	johnsonm@...th.com, tglx@...utronix.de
Subject: [tip:x86/urgent] x86: more than 8 32-bit CPUs requires X86_BIGSMP

Commit-ID:  2a3313f494c2f3f74a27d66f0f14b38558b7dba2
Gitweb:     http://git.kernel.org/tip/2a3313f494c2f3f74a27d66f0f14b38558b7dba2
Author:     Michael K. Johnson <johnsonm@...th.com>
AuthorDate: Tue, 21 Apr 2009 21:44:48 -0400
Committer:  H. Peter Anvin <hpa@...or.com>
CommitDate: Tue, 21 Apr 2009 19:34:54 -0700

x86: more than 8 32-bit CPUs requires X86_BIGSMP

$ cat x86-more-than-8-cpus-requires-bigsmp.patch

Enforce NR_CPUS <= 8 limitation if X86_BIGSMP not set

Configuring more than 8 logical CPUs on 32-bit x86 requires
X86_BIGSMP to be set in order to boot successfully, if more than 8
logical CPUs are actually found at boot time.  The X86_BIGSMP help
text describes that it is required to be set if more than 8 CPUs
are configured, but this was previously not enforced.

This configuration error has affected multiple distributions:
    https://bugzilla.redhat.com/show_bug.cgi?id=480844
    https://issues.rpath.com/browse/RPL-3022

Signed-off-by: Michael K Johnson <johnsonm@...th.com>
LKML-Reference: <20090422014448.GB32541@...o.rdu.rpath.com>
Signed-off-by: H. Peter Anvin <hpa@...or.com>


---
 arch/x86/Kconfig |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c9086e6..b5cda6c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -664,6 +664,7 @@ config MAXSMP
 
 config NR_CPUS
 	int "Maximum number of CPUs" if SMP && !MAXSMP
+	range 2 8 if SMP && X86_32 && !X86_BIGSMP
 	range 2 512 if SMP && !MAXSMP
 	default "1" if !SMP
 	default "4096" if MAXSMP
--
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