Messages in this thread |  | | Subject | Re: Linus' laptop and Num lock status | From | Dax Kelson <> | Date | Wed, 14 Feb 2007 14:34:00 -0700 |
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On Wed, 2007-02-14 at 11:32 -0800, Linus Torvalds wrote: > > On Wed, 14 Feb 2007, Jean Delvare wrote: > > > > On x86, the BIOS led state can be read from byte 0x97 the BIOS RAM. The > > BIOS RAM is mapped at 0x400 so all we need to do is to one byte from > > RAM (offset 0x497). This is how Suse's hwinfo does. > > Heh. Shows just how much I ever used DOS and BIOS. > > > But maybe the first question to ask is: why is the BIOS setting lost in > > the first place? Why is the kernel resetting the led state? > > Ehh. Silly question. "Those flags, they do nothing." > > The kernel needs to know what they are in order to react correctly to > them. And since you can't read them from hardware, the only way to know > what they are (if you don't know about BIOS magic areas) is to SET THEM. > > Which is what the kernel has traditionally always done.
Going forward can the kernel peek at 0x497 and follow the BIOS setting?
I checked, and looking at offset 0x497 seems to work fine on a couple of systems with USB keyboards.
People have long grumbled and complained about the current kernel behavior (1).
Dax Kelson
(1) http://lkml.org/lkml/1999/2/27/6 http://www.google.com/search?q=linux+num+lock https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=115909
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