When compiling a kernel on my system with
ACPI_VIDEO on, it compiles and boots fine, but will not
accept any keyboard input.

Disabling ACPI_VIDEO produces a perfectly functional kernel (without brightness control). This is true for a large number of different graphics configurations
(disable/enable framebuffer etc.)


Note that this has nothing to do with X. X was disabled completely
under my tests.

Adding if [[ ! -e /root/dmesg ]]; then dmesg > /root/dmesg ; fi
to my /etc/conf.d/local.start file (the last init script)
produces an empty /root/dmesg file (!!!). Therefore, I have
not attached dmesg output.


Hypothesis: Pressing Fn+f4 and Fn+f5 (for brightness control)
sends a keycode (from /var/log/messages):
Fn+f4:
  (empty)
Fn+f5:
Jul  3 22:28:50 localhost atkbd.c: Unknown key pressed (translated set 2, code 0xf8 on isa0060/serio0).
Jul  3 22:28:50 localhost atkbd.c: Use 'setkeycodes e078 <keycode>' to make it known.
Jul  3 22:28:50 localhost atkbd.c: Unknown key released (translated set 2, code 0xf8 on isa0060/serio0).
Jul  3 22:28:50 localhost atkbd.c: Use 'setkeycodes e078 <keycode>' to make it known.

For the ACPI system to receive the keycodes, it has to at least modify the
keyboard handler code. Somewhy, on my system, this breaks the handler.

For lspci, .config, cpuinfo, see my initial post on the Gentoo forums:
http://forums.gentoo.org/viewtopic-t-776516.html

Anders Søndergaard