Comment 11 for bug 178860

well sorry i don't have time to always have the latest-and-greatest ubuntu installed :ep

anyway.
restating the issue:
all special function keys work as expected, but they generate "unknown keycode" noise in dmesg. when attempting to fix the noise by including keys in a hotkey map, gnome brightness settings go haywire.

therefore, the troubleshooting steps don't really apply (as the keys do work)

from what i can tell, the problem is that the keys in question are sent both as an acpi event, seen by acpi_listen like this:
video DD04 00000087 00000000
video DD04 00000086 00000000
and as a key event, reported by kernel like this:
[ 1296.600041] atkbd.c: Unknown key pressed (translated set 2, code 0xf7 on isa0060/serio0).
[ 1296.600046] atkbd.c: Use 'setkeycodes e077 <keycode>' to make it known.
[ 1296.600962] atkbd.c: Unknown key released (translated set 2, code 0xf7 on isa0060/serio0).
[ 1296.600966] atkbd.c: Use 'setkeycodes e077 <keycode>' to make it known.
[ 1296.980697] atkbd.c: Unknown key pressed (translated set 2, code 0xf8 on isa0060/serio0).
[ 1296.980702] atkbd.c: Use 'setkeycodes e078 <keycode>' to make it known.
[ 1296.981615] atkbd.c: Unknown key released (translated set 2, code 0xf8 on isa0060/serio0).
[ 1296.981618] atkbd.c: Use 'setkeycodes e078 <keycode>' to make it known.

the keys register in xev output properly:
KeyPress event, serial 31, synthetic NO, window 0x2800001,
    root 0x10b, subw 0x0, time 1609238, (352,590), root:(359,643),
    state 0x0, keycode 232 (keysym 0x1008ff03, XF86MonBrightnessDown), same_screen YES,
    XLookupString gives 0 bytes:
    XmbLookupString gives 0 bytes:
    XFilterEvent returns: False

also, setting brightness works independent of gnome-power-manager (which is good and please don't "fix" this ;e) )

this is with the keys not in the keymap. i'll try to test what happens with a proper keymap