linux-kernel - [PATCH] x86: limit mwait

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Date:	Thu, 5 Apr 2007 16:00:45 +0200
From:	"Andreas Herrmann" <andreas.herrmann3@....com>
To:	linux-kernel@...r.kernel.org, "Andi Kleen" <ak@...e.de>
Subject: [PATCH] x86: limit mwait_idle to Intel CPUs


Commit 991528d7348667924176f3e29addea0675298944
introduced mwait_idle which is supposed to work
for Intel CPUs starting with Core Duo.

AMD Fam10 processors won't enter C1 on mwait.
This patch will enable default_idle for non-Intel
CPUs even if mwait is supported.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com>
---
 arch/i386/kernel/process.c   |    4 +++-
 arch/x86_64/kernel/process.c |    3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 393a67d..e3067e4 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -259,7 +259,9 @@ static void mwait_idle(void)
 
 void __devinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
-	if (cpu_has(c, X86_FEATURE_MWAIT)) {
+	if (cpu_has(c, X86_FEATURE_MWAIT) &&
+	    (c->x86_vendor == X86_VENDOR_INTEL)) {
+
 		printk("monitor/mwait feature present.\n");
 		/*
 		 * Skip, if setup has overridden idle.
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index d8d5ccc..fed830c 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -271,7 +271,8 @@ static void mwait_idle(void)
 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
 {
 	static int printed;
-	if (cpu_has(c, X86_FEATURE_MWAIT)) {
+	if (cpu_has(c, X86_FEATURE_MWAIT) &&
+	    (c->x86_vendor == X86_VENDOR_INTEL)) {
 		/*
 		 * Skip, if setup has overridden idle.
 		 * One CPU supports mwait => All CPUs supports mwait
-- 
1.5.0.6




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