Naive question on brightness keys

[Radu-Cristian FOTESCU]

--- Hans-Werner Hilse <hilse at web.de> wrote:
>
> Yes, provided by software and specialized daemons. Linux has hardware
> support for a lot of those special interfaces that have to be used for
> controlling such things like backlight. Other OSs might also bring such
> support. Usually, these kernel interfaces have to be controlled from
> userland. Daemons sitting there and reacting on keystrokes (which
> themselves might only be readable by specialized interfaces) issue
> commands to the kernel to take appropriate actions. Having APM enabled
> often keeps some of the BIOS functions alive and kicking. There's no
> guarantee, though. I guess in case of the other systems some bring the
> proper drivers and some don't (e.g. Gentoo: You're the one to configure
> the kernel!). Some bring an initial desktop environment that has
> configured support for those things (e.g. have khotkeys configured and
> running), some don't. Some might even skip ACPI and bring rudiments of
> the BIOS provided functionality. Most of the systems are configurable
> w/ regard to all this. My basic point is: There's actually some effort
> needed to support this explicitly. It's not about some efforts that
> lead to have those things dysfunctional.

Wee, thank you very much! I assume that the said differences were because
different distros compiled the kernel with different ACPI options. As for the
BSDs, they're different (DragonFly different from 2 others).

I can have now a place to digg, in various OSes. I might eventually need to
learn where to digg, as on this bloody Acer (a new motherboard design, 2007),
I can't get the wireless enabling button to do anything, so regardless of the
ndiswrapper loading the correct driver, it simply can't be activated. (I hate
buttons that enable things, as long as they're not real on/off buttons!)

> 
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/thinkpad-acpi.txt;hb=HEAD

Very interesting. A good pointer indeed, even if I don't have a Thinkpad.

Minor note: it seems there are/were some buttons "handled purely in
hardware". To quote the document:

"Internal mixer volume up. This key is always handled by the firmware, even
when unmasked."

"Mute internal mixer. This key is always handled by the firmware, even when
unmasked."

It is not the case with Acer, but it's good to know that handling through
hardware could (should!) have been an option.

Thanks again,
R-C



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