Brigthness fix for Acer Aspire 5738z with Ubuntu 9.10

The brightness keys on this laptop (Fn + left/right arrow keys), do not work out of the box on Ubuntu. It does not work on 9.04 (Jaunty Jalopy) and continued to not work in 9.10 (Karmic Koala).

The work around for this is modifying your kernel command line to add "acpi_osi=Linux nomodeset acpi_backlight=vendor". One way to do this is to modify (or safer yet copy) a kernel entry in menu.1st file of the grub bootloader.

So for example if your boot directory is /boot/ then menu.1st is in /boot/grub/menu.1st.

I edited my latest kernel like so:
Old entry ->

title           Ubuntu 9.10, kernel 2.6.31-20-generic
uuid            some_id
kernel          /boot/vmlinuz-2.6.31-20-generic
root=UUID=some_id ro quiet splash
initrd          /boot/initrd.img-2.6.31-20-generic
quiet

New entry ->

title           *Brigthness fix* Ubuntu 9.10, kernel 2.6.31-20-generic
uuid            some_id
kernel          /boot/vmlinuz-2.6.31-20-generic root=UUID=some_id
ro quiet splash acpi_osi=Linux nomodeset acpi_backlight=vendor
initrd          /boot/initrd.img-2.6.31-20-generic
quiet

Taken from this thread:https://bugs.launchpad.net/ubuntu/+source/acpid/+bug/392948