Re: beeping patch for debugging acpi sleep

Hi!

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@xxxxxxx>

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)


How does the beep get turned off again?

Typically, pcmcia beeps after resume, making it quiet. If not, echo ^G
does it.

Should the BEEP line be uncommented (in -mm at least)?

It's too gross a hack, I'd say. It is only ever useful if machine is
completely dead after s2ram.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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