It looks like thinkpads have a non standard ACPI device that handles the fan control, among other things. That is where /proc/acpi/ibm comes from. It is implemented in the kernel in drivers/platform/x86/thinkpad_acpi.c, and has some comments pointing to:
It looks like thinkpads have a non standard ACPI device that handles the fan control, among other things. That is where /proc/acpi/ibm comes from. It is implemented in the kernel in drivers/ platform/ x86/thinkpad_ acpi.c, and has some comments pointing to:
http:// thinkwiki. org/wiki/ Embedded_ Controller_ Firmware# Firmware_ Issues