Inspiron 4100 system fans do not run without i8k.o, but i8k.o permanently disables keyboard

Binary package hint: i8kutils

Problem found on a Dell Inspiron 4100 laptop running xubuntu 9.04.

This laptop has two variable-speed cooling fans, one each on the CPU and the graphics chipset. On a default *ubuntu install, the cooling fans never run, causing the laptop to overheat. By adding the i8kutils package and loading the i8k kernel module, it is possible to gain control over the fans, either manually via i8kfan/i8kctl or automatically via i8kmon.

Unfortunately, when i8k.o is loaded, it immediately and permanently (until next reboot) disables the laptop's keyboard and pointing devices. An external USB keyboard will continue to work, but even if i8k.o is unloaded, the laptop keyboard and pointing devices cannot be re-enabled except by rebooting the laptop. The net result is that with i8k.o loaded, the laptop is usable only with an external keyboard; without i8k.o, it is usable only until it overheats.

I have WORKED AROUND this problem for now by the following measures:
1) Compile a custom kernel with APM instead of ACPI
2) In that custom kernel, modify i8k.c to never attempt to mess with the fn-keys
I don't know yet which if the two - never getting or setting the fn-keys, or using APM instead of ACPI - is the actual workaround. I'll test that more later. But with those two modifications, i8k can be loaded (and i8kctl and i8kmon used) without killing the keyboard.

Additional information:
I ALSO discovered, during the process, that the i8kmon documentation (i8kmon.1) is both incomplete and incorrect. The config file /etc/i8kmon is documented as being optional, and only the 'set config(n) ...' directive for it is described. It's true, the file IS optional, as long as you don't care whether i8kmon is started; /etc/init.d/i8kmon will start /usr/bin/i8kmon if and only if /etc/i8kmon exists AND contains the directive 'set config(daemon) 1'.