linux-kernel - beeping patch for debugging acpi sleep

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Date:	Sat, 9 Jun 2007 15:08:17 +0200
From:	Pavel Machek <pavel@....cz>
To:	Christian Leber <christian@...er.de>,
	Andrew Morton <akpm@...l.org>,
	kernel list <linux-kernel@...r.kernel.org>
Subject: beeping patch for debugging acpi sleep


Starting beeper as soon as ACPI sleep returns is very useful in
debugging "apparently dead" machines. If it beeps at all, it makes
sense to start playing with CMOS tracer.

Signed-off-by: Pavel Machek <pavel@...e.cz>

diff --git a/arch/i386/kernel/acpi/wakeup.S b/arch/i386/kernel/acpi/wakeup.S
index b781b38..cbf136e 100644
--- a/arch/i386/kernel/acpi/wakeup.S
+++ b/arch/i386/kernel/acpi/wakeup.S
@@ -11,7 +11,22 @@ # Do we need to deal with A20? It is oka
 #
 # If physical address of wakeup_code is 0x12345, BIOS should call us with
 # cs = 0x1234, eip = 0x05
-# 
+#
+
+#define BEEP \
+	inb	$97, %al; 	\
+	outb	%al, $0x80; 	\
+	movb	$3, %al; 	\
+	outb	%al, $97; 	\
+	outb	%al, $0x80; 	\
+	movb	$-74, %al; 	\
+	outb	%al, $67; 	\
+	outb	%al, $0x80; 	\
+	movb	$-119, %al; 	\
+	outb	%al, $66; 	\
+	outb	%al, $0x80; 	\
+	movb	$15, %al; 	\
+	outb	%al, $66;
 
 ALIGN
 	.align	4096
@@ -20,6 +35,9 @@ wakeup_code:
 	wakeup_code_start = .
 	.code16
 
+# Uncomment this to make your computer start producing ugly noise as soon
+# as BIOS returns to this real-mode entry point.
+#	BEEP
  	movw	$0xb800, %ax
 	movw	%ax,%fs
 	movw	$0x0e00 + 'L', %fs:(0x10)

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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