I FreeBSD 11.0-RC3, I can change screen brightness with sysctl: root@bsd-esalgado:/usr/home/esalgado # sysctl hw.acpi.video.lcd0.brightness=60 hw.acpi.video.lcd0.brightness: 70 -> 60 When pushing screen brightness control buttons, nothing happens. Using xev, I can see that no event is triggered when pushing those buttons: KeyPress event, serial 36, synthetic NO, window 0x2000001, root 0xb6, subw 0x0, time 613282, (166,-15), root:(427,234), state 0x0, keycode 146 (keysym 0x0, NoSymbol), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x2000001, root 0xb6, subw 0x0, time 613383, (166,-15), root:(427,234), state 0x0, keycode 146 (keysym 0x0, NoSymbol), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 36, synthetic NO, window 0x2000001, root 0xb6, subw 0x0, time 613858, (166,-15), root:(427,234), state 0x0, keycode 151 (keysym 0x0, NoSymbol), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x2000001, root 0xb6, subw 0x0, time 613941, (166,-15), root:(427,234), state 0x0, keycode 151 (keysym 0x0, NoSymbol), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False