[tip:perf/core] x86, nmi: Define a name for NMI control port
From: tip-bot for Cyrill Gorcunov
Date: Wed Mar 02 2011 - 13:46:31 EST
Commit-ID: 0f5dbad5ecab0921911966e857eab408ef32163c
Gitweb: http://git.kernel.org/tip/0f5dbad5ecab0921911966e857eab408ef32163c
Author: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
AuthorDate: Wed, 2 Mar 2011 18:32:30 +0300
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 2 Mar 2011 16:44:44 +0100
x86, nmi: Define a name for NMI control port
Also add a comment about why we need in/out operations.
Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
LKML-Reference: <4D6E630E.1070107@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/include/asm/mach_traps.h | 18 +++++++++++++-----
1 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/mach_traps.h b/arch/x86/include/asm/mach_traps.h
index 72a8b52..7775deb 100644
--- a/arch/x86/include/asm/mach_traps.h
+++ b/arch/x86/include/asm/mach_traps.h
@@ -8,6 +8,7 @@
#include <asm/mc146818rtc.h>
#define NMI_REASON_PORT 0x61
+#define NMI_ENABLE_PORT 0x70 /* Real-Time Clock Address Register as well */
#define NMI_REASON_SERR 0x80
#define NMI_REASON_IOCHK 0x40
@@ -30,12 +31,19 @@ static inline void reassert_nmi(void)
old_reg = current_lock_cmos_reg();
else
lock_cmos(0); /* register doesn't matter here */
- outb(0x8f, 0x70);
- inb(0x71); /* dummy */
- outb(0x0f, 0x70);
- inb(0x71); /* dummy */
+
+ /*
+ * This will cause the NMI output to transition low
+ * then high if there are any pending NMI sources. The
+ * CPU's NMI input logic will then register a new NMI.
+ */
+ outb(0x8f, NMI_ENABLE_PORT);
+ inb(0x71); /* dummy */
+ outb(0x0f, NMI_ENABLE_PORT);
+ inb(0x71); /* dummy */
+
if (old_reg >= 0)
- outb(old_reg, 0x70);
+ outb(old_reg, NMI_ENABLE_PORT);
else
unlock_cmos();
}
--
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