Comment 16 for bug 1203592

If you are using UEFI, do not remove the blacklist on samsung-laptop!

You are probably safe from the bricking bug with a recent kernel, but there are other UEFI problems with samsung-laptop that have never been resolved, like machine check exceptions.

I did find a way of setting the keyboard backlight without the samsung-laptop module, but I am still working on it.

The ACPI DSDT defines a variable KBLL (keyboard back-light level?) in the SNVS (system non-volatile storage). This is where the the backlight level can be stored, but it is highly non-trivial to set. I wrote a program for my own machine, but it has hard-coded memory addresses which probably make it very unwise to run on other systems.

A slightly safer way, which requires a reboot to work, is to set the keyboard backlight level in the UEFI variables.

On my system:

# cd /sys/firmware/efi/efivars
# ls *KeyboardBacklight*
SecKeyboardBacklightLevel-2f440835-38c4-44b6-b7e4-4f321c8b4189
# xxd -p SecKeyboardBacklightLevel-2f440835-38c4-44b6-b7e4-4f321c8b4189
0700000001
# echo 0700000005 | xxd -p -r > SecKeyboardBacklightLevel-2f440835-38c4-44b6-b7e4-4f321c8b4189
# reboot

You can change that last byte from 00 through 06 or so. Don't change the first or other bytes. At some stage during the next boot, it will be read into the KBLL value mentioned above.

I use '01' pretty well permanently. Now that recent kernels detect the ambient light properly, it comes on automatically when I need it.