.
I've seen the light with uefi, but it's too bright for me.

I have two Dell Inspiron laptops: One is a Win7 Model 1545 with Legacy boot,
the other a Win8 Model 3520 with uefi boot.

A Knoppix 7.4.2 LiveUSB with reiserfs persistence developed on the 1545 works
as well on the 3520 with one peculiar exception. The backlight on the 3520 is
uncomfortably bright.

My first attempt to correct this situation was to add a line in /etc/rc.local
commanding 'sudo /usr/bin/xbacklight 60' which works at a command line. But
it doesn't work at rc.local. Apparently /etc/rc.local does not apply after
all other init processes are done, after all.

I recall that it was convenient to use /etc/X11/Xsession.d/45knoppix as a
vehicle to remedy other things that rc.local no longer cured. So I've located
my xbacklight command in 45knoppix as well, and it serves the purpose.

So, I offer this Knoppix work-around if Win8 illumination is just too bright
to accept.