Errata ROSA Desktop R3
From Rosalab Wiki
The keys to control brightness do not work on Samsung N100 laptop
This may affect other laptops as well.
Solution: add 'acpi_backlight=vendor' kernel parameter at boot time (without quotes).
To make it persistent, edit /etc/default/grub: specify that parameter in the GRUB_CMDLINE_LINUX_DEFAULT variable. Then, execute update-grub2
.