Thread (5 messages) 5 messages, 3 authors, 2008-01-14

Re: [PATCH] Default keyboard LEDs

From: "H. Peter Anvin" <hpa@zytor.com>
Date: 2008-01-14 03:51:05
Also in: lkml

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 <samuel.thibault@ens-lyon.org>

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:

--------K-M00400017--------------------------
MEM 0040h:0017h - KEYBOARD - STATUS FLAGS 1
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.

	-hpa
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