acpi=off disables Fn key combinations on ThinkPad

[Chris Leith]

Configuration: FC3T2 with kernel 2.6.8-1.584

Using acpi=off in the kernel command line (to disable acpi and use apm
instead) causes the Fn key (and any combinations) on my ThinkPad T41 to
not respond. Even things like tpb package (can be used in conjunction
with xosd to show an on screen volume level, for example) no longer work
when acpi=off is used. Without acpi=off tpb works fine and some of the
Fn key combinations are registered. I prefer to use apm, however.
Previously, using acpi=off worked flawlessly (suspend to ram using apm,
all Fn key combos working) with a 2.6.6 kernel in FC2.

Can anyone shed some light on this change in behaviour?

Thanks in advance,

-Chris