linux-kernel - Re: beeping patch for debugging acpi sleep

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Message-ID: <20070611085652.GA4032@suse.de>
Date:	Mon, 11 Jun 2007 10:56:52 +0200
From:	Stefan Seyfried <seife@...e.de>
To:	Pavel Machek <pavel@....cz>
Cc:	Christian Leber <christian@...er.de>,
	Andrew Morton <akpm@...l.org>,
	kernel list <linux-kernel@...r.kernel.org>
Subject: Re: beeping patch for debugging acpi sleep

On Sat, Jun 09, 2007 at 03:08:17PM +0200, Pavel Machek wrote:

How about (WARNING! I never have written i386 assembly, my last assembly
experience was 20 years ago on Z80, so this is basically just copy'n paste,
but i hope you get the idea):

> --- a/arch/i386/kernel/acpi/wakeup.S
> +++ b/arch/i386/kernel/acpi/wakeup.S

> @@ -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.

        testl   $4, video_flags - wakeup_code
        jz      1f
> +	BEEP
   1:
>   	movw	$0xb800, %ax
>  	movw	%ax,%fs
>  	movw	$0x0e00 + 'L', %fs:(0x10)

IIUC, then this should make "echo 4 > /proc/sys/kernel/acpi_video_flags"
enable the beep at run-time.

Yes, i know, it is not a video flag. And not ACPI. Just add another
sysctl if you care.
-- 
Stefan Seyfried
QA / R&D Team Mobile Devices        |              "Any ideas, John?"
SUSE LINUX Products GmbH, Nürnberg  | "Well, surrounding them's out." 

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