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From: "H. Peter Anvin" <>
To: Samuel Thibault <>,,
Subject: Re: [PATCH] Default keyboard LEDs
Date: Sun, 13 Jan 2008 19:50:34 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20080114005219.GA4296@implementation>

Samuel Thibault wrote:
> In many cases, one prefers to have e.g. the NumLock on by default.  In
> many cases, one doesn't want to have it by default, e.g. on laptops.
> Distributions actually have a very hard time trying to set this
> correctly after the kernel boot, and that doesn't work for new consoles
> that are created via the openvt(1) command anyway. This hence adds a
> keyboard.default_leds boot parameter that permits to configure the
> default keyboard LEDs.
> Signed-off-by: Samuel Thibault <>
> Actually, what would be perfect would be to use the configuration that
> the BIOS sets at boot by default.  That is device-dependent, however.

It is, but it can be read out either by INT calls at initialization 
time, or by reading out the byte at physical address 0x417:

Size:   BYTE
SeeAlso: MEM 0040h:0018h,INT 16/AH=02h,MEM 0040h:0096h

Bitfields for keyboard status flags 1:
Bit(s)  Description     (Table M0010)
  7      INSert active
  6      Caps Lock active
  5      Num Lock active
  4      Scroll Lock active
  3      either Alt pressed
  2      either Ctrl pressed
  1      Left Shift pressed
  0      Right Shift pressed
SeeAlso: #M0011,#00587

The same information is available through INT 16h, AH=02h.


  parent reply	other threads:[~2008-01-14  3:51 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-14  0:52 Samuel Thibault
2008-01-14  1:40 ` Jan Engelhardt
2008-01-14 10:24   ` Samuel Thibault
2008-01-14  3:50 ` H. Peter Anvin [this message]
2008-01-14 10:27   ` Samuel Thibault

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