[K42-discussion] G5 thermal management patches for kitchsrc and linux-029

[Michal Ostrowski]

> >
> >Unless Michal has objections, I will go through this patch tomorrow and
> >commit it if I don't see anything wrong.  Have you stress tested it
> >(hopefully sitting in front of the machine with the ability to yank the
> >power)?  I'd hate to melt your or somebody else's procesor ...
> >  
> >
> I've tested it some and initial tests seemed ok but you should probably
> do more before a commit is made since I haven't put it under as much
> stress as it deserves. I am probably too trusting of the fact that that
> the therm code is a direct copy of the linux code.  And since it isn't
> really running under a full linux kernel, this trust may be unfounded.
> 
> >  

I'm fairly certain that I've fried 2 CPUs in the past (go try explaining
that to Apple service techs).  Things get fun when the K42 debugger
kicks in: it results in interrupts not being processed for a long time,
not to mention some serious potential "time warp" effects observed by
Linux code.

If you're not running the debugger then the fan control code behaves
really closely to what happens in Linux.

When you turn the debugger on:

- at least one CPU ends up spinning tightly in a loop reading of the
serial port (higher temp?)

- fan control code may not get kicked (if you're debugging on the CPU
that is to get that interrupt).

- you better hope that the fan control HW will take over and rev up the
fans.


Michal