"acpitool -l" fails because /proc/acpi/ibm/brightness is missing

[Alex Rolfe]

After upgrading from Gutsy to Hardy, "acpitool -l" fails to change the screen brightness because /proc/acpi/ibm/brightness no longer exists. That path is hardcoded into the acpitool (0.4.7-1ubuntu1) source, so I'm not sure whether to blame this on acpitool on the acpi drivers. /proc/acpi/video/VID/LCD0/brightness can be used to change the brightness, though the values it accepts (30 40 50 60 70 80 90 100) are different than what /proc/acpi/ibm/brightness took (0 through 7).

The hardware is a Thinkpad T60.
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu hardy (development branch)"
$ uname -r
2.6.24-10-generic