This bug was originally reported in Ubuntu at Launchpad https://bugs.launchpad.net/ubuntu/+source/linux/+bug/173366 " None of hotkeys of the sony vaio VGN-BX296XP seem to work apart from the mute button (which seems to be hw implemented). I contacted the developer of the sony_laptop module and he replied that my laptop seems to be using the GHKE method. The dmesg output shows the same scan code for ALL keys: Use 'setkeycodes e075 <keycode>' to make it known. [Unknown key released (translated set 2, code 0xf5 on isa0060/serio0)." The problem is that every non-working FN-hotkey gives the same scancode, which suggests it could be kernel related. Thank you.
There is a userspace utility fsfn which somehow captures the FN keypresses. http://developer.berlios.de/bugs/?group_id=4604 Source code is browsable at: http://svn.berlios.de/wsvn/fsfn/trunk/fsfn/src/#_trunk_fsfn_src_ The GHKE ACPI method used (>2 years ago) to work for the FN-keys in the vanilla kernel. If I read http://www.mail-archive.com/linux-acpi@vger.kernel.org/msg04257.html it seems this was the case when sony_acpi.c was still in use.