Hello,

> > There's a note in powerpc/oea/cpu_subr.c
> > 
> > #if NSYSMON_ENVSYS > 0
> > /*
> >  * Attach MPC750 temperature sensor to the envsys subsystem.
> >  * XXX the 74xx series also has this sensor, but it is not
> >  * XXX supported by Motorola and may return values that are off by
> >  * XXX 35-55 degrees C.
> >  */
> > if (vers == MPC750 || vers == IBM750FX)
> >       cpu_tau_setup(ci);
> > #endif
> 
> That's my doing. The 74xx series manuals are pretty clear that the
> temperature sensor on the chip is not supported or even expected to
> work.
Hmm, I found conflicting information about that, apparently the TAU works in /some/ G4s ( or at least some people say so ).
On the other hand - I'd rather believe the manuals and sure enough, my 7455 thinks it's 4C cold - not really believable ;)

> That said, Apple laptops have more thermal sensors than the one on the
> CPU, so finding them (probably i2c devices with OFW entries somewhere)
> and adding them to envsys would be a nice little project.
I added a quick hack to ki2c.c to scan for devices but either I'm doing something wrong, the code doesn't really work for some reason or there are no devices connected. ( 12" iBook G4 )
The first one seems to be the most probable though :)

have fun
Michael