[coreboot] PECI temperature in lm-sensors

Nico Huber nico.h at gmx.de
Mon Jan 23 21:41:54 CET 2017


On 23.01.2017 15:17, Аладышев Константин wrote:
> Does someone have any experience with enabling PECI monitoring on nuvoton
> SuperIOs ?
> 
> I'm trying to enable it on board with Haswell+Lynxpoint CPU and  NCT6776
> SuperIO.
> 
> But all I see in lm-sensors output for now is zero temperature for PECI
> Agent.

I'd first make sure, that the PECI interface is actually connected to a
PECI slave. Do you have evidence that this is the case? It's not unusual
to leave it unconnected.

> 
> Does coreboot have any SuperIO chips/Intel CPUs/motherboards, that have this
> functional enabled? What is usually need to be done to enable PECI
> monitoring?

FWIW (cf. superio/ite/it8772f and others), you have to program the PECI
slave address and the command used to retrieve the temperature readings.
What to program seems to be documented in a secret PECI specification (I
could only find a license agreement, WTF?). How to program it, is super
i/o specific (see datasheet of your chip).

I wonder though, what are you up to? You only need PECI if you want your
super i/o to to something automatically (like fan control) based on the
readings. If you only want to read out the temperature, you can also
directly ask the processor (MSR 0x19c, IIRC).

Nico



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