linux-kernel - [PATCH] x86: Don't use NOPL on 32-bit cpu's because not all systems support it.

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Date:	Tue, 16 Sep 2008 11:59:15 -0400
From:	David Sanders <linux@...dersweb.net>
To:	"the arch/x86 maintainers" <x86@...nel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] x86: Don't use NOPL on 32-bit cpu's because not all systems support it.

From: David Sanders <linux@...dersweb.net>

Currently in alternative.c NOPLs are introduced based on the synthetic
cpu feature X86_FEATURE_NOPL.  However, some systems (like Virtual PC 2007)
appear to support it but then will not boot 50% of the time because of
the NOPLs (when paravirtualization support is built into kernel).
This patch standardizes the treatment of NOPL to be like
include/asm-x86/nops.h which only uses NOPLs on 64-bit processors.

Applies to 2.6.27-rc6.

Signed-off-by: David Sanders <linux@...dersweb.net>
---
 arch/x86/kernel/alternative.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 65a0c1b..dceb843 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -160,8 +160,12 @@ const unsigned char *const *find_nop_table(void)
 		return k8_nops;
 	else if (boot_cpu_has(X86_FEATURE_K7))
 		return k7_nops;
-	else if (boot_cpu_has(X86_FEATURE_NOPL))
-		return p6_nops;
+	/*
+	 * Don't use NOPL in 32-bit mode because some Emulators
+	 * do not support it.
+	 */
+	/* else if (boot_cpu_has(X86_FEATURE_NOPL))
+		return p6_nops; */
 	else
 		return intel_nops;
 }
--
1.6.0.2.229.g1293c
--
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