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 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/751689 Title: Thinkpad x201* overheats due to slow fans when on 'auto' -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
