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[anthill]

I got tired of watching Teapot's Ubuntu boot up in full backlight brightness mode, so I figured out how to turn the backlight down (or off) at startup.  Not for the cautious, though, as you will be editing a critical startup file and a saved typo could stop your laptop booting.

You  need to add some FORTH code to be run by the laptop's Open Firmware.  Basically the code is:

Code:

screen-ih iselect
1 bright!

where the number can range from 0 to 9, plus the hexadecimal A-F.  0 is no backlight, F is full brightness (the default).  To get a pretty fading effect, you can edit your /boot/olpc.fth file and add:

Code:

\ Dim screen from full to 1/15th brightness with 2.5ms delay between steps
screen-ih iselect
1 F do i bright! 2500 us -1 +loop

to the last lines, just before boot is called.

Be careful!  If you want to test that this command is correct, reboot and tap the Escape (circle-X) key until you get an 'ok' prompt.  Type the screen dimming command and verify that it works.

Good luck!