So, I couldn’t figure out how to get my Macbook function keys to default to function keys under Linux, rather than media keys such as brightness, volume control, etc. I searched all over the net for information on this feature, and could only find stuff about pb_fnmode (which doesn’t appear in the latest kernels). So, I finally resorted to grepping “fnmode” out of the sources, and found the location that sets this. Then, I noticed that the kernel module that handles Mac key mappings had a parameter that could be changed, called “fnmode”. Well, that gave me a clue that it may be in /sys/ somehwere. So, I searched, and sure enough, it was there. The following command will set the function keys to be the default action, rather than media keys.
echo 2 > /sys/module/hid_apple/parameters/fnmode
The valid values are (0 = disabled,  = fkeyslast, 2 = fkeysfirst)
This effectively reverses the function key/media key mappings.