Cannot change FN lock behavior on XPS 9560

Question

I got my new XPS 15 9560 about a week ago and I am currently dual booting Ubuntu 16.04 LTS and Windows 10, with the latest BIOS update (1.3.4). The laptop has secondary functions for the f1-f12 keys like changing screen brightness and speaker volume. By default, when you press the f-keys, these secondary functions are activated and you must hold the Fn key to have the keys work like regular function keys. It is possible to switch them to have regular f-key input as their normal operation (so that you have to hold Fn for the secondary functions) by pressing Fn + Esc, however I have little use for the secondary functions and would much rather have the regular function key behavior as the default without having to press Fn + Esc on every boot.

There is of course a setting for this in the UEFI BIOS (called Fn Lock) and I attempted to change this setting to have the function keys work normally by default rather than as media keys. However, when I boot the laptop into both Windows and Ubuntu, the behavior does not change - I must still press Fn + Esc to have normal function key behavior. When I shut the machine down and go back into the BIOS, the setting for Fn Lock has magically reverted to its original state (Fn keys act as media keys). All the research I have done on this issue simply says to change this setting in the BIOS, but I have no idea how both operating systems seem to be overriding this value. I would appreciate some insight on how to stop this from changing.

Answer 1

I have come to the realization that the BIOS options are very confusingly labeled. It turns out that setting the Fn Lock behavior to "Disabled/Standard" does not lock the f-keys to their normal, f1-f12 input but rather to their media key functions. If you want to access the normal input, you must set the BIOS to "Enabled/Secondary". It appears that Dell defines secondary functions the normal behavior of f-keys and standard functions as media keys. I also realized that pressing Fn + Esc persists aross reboots, and it is what actually changes the BIOS setting.