[CentOS] Checking fan state
John R Pierce
pierce at hogranch.com
Tue Jan 6 01:49:25 UTC 2009
re: thermal sensors... I did a bit of googling. This NC2400 laptop is
based on the Intel 945GM chipset w/ the ICH7 southbridge. the 945GM
does -not- implement that ME (Management Engine) stuff I previously
described, instead, it has thermal sensors on a smbus, along with some
interesting heuristic logic that attempts to guess how hot the memory is
getting based on cycle rate, and tuned by some registers which can be
loaded either with BIOS presets or from memory DIMM SPD values... all
of this is used to trip 4 possible throttle states just for the GMCH
(northbridge)... the Northbridge apparently signals the host
{bios|os}via ACPI IRQ to manage the fans.
I found the stuff about memory throttling fascinating reading... Chapter
10.7 of http://www.intel.com/Assets/PDF/datasheet/309219.pdf (the 945GM
(G)MCH chip)
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