My laptop is a toshiba qosmio x770 with ubuntu 12.04 64-bit and backlit keyboard doesn't work when I select ubuntu in boot. When I click in "Fn+z" to enable-disable backlit keyboard (in windows works perfectly) appear a popup, like volume control, with a full grey bar, but they never worked in ubuntu.
I already tried "acpi=off" and ubuntu doesn't boot.

Any ideas?
Thanks