linux-kernel - Re: Linus' laptop and Num lock status

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Date:	Thu, 15 Feb 2007 06:25:00 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Dax Kelson <dax@...ulabs.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Jean Delvare <khali@...ux-fr.org>
Subject: Re: Linus' laptop and Num lock status

Linus Torvalds wrote:
> 
> On Wed, 14 Feb 2007, Dax Kelson wrote:
>> Are there any technical or political reasons why kernel can't change
>> from "force off" to "Follow BIOS"?
> 
> How would you query it? I'm not even 100% sure that you can on all 
> keyboards. We never query the leds, we always set them. I think. I don't 
> know of any AT kbd command to read the led state out of the keyboard.
> 

You can query the state of the keyboard according to BIOS by looking in 
byte 0x417 absolute, or by issuing int 0x16, ah = 0x02 (or ah = 0x12) 
from real mode.

	-hpa

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