Re: SMU support for PowerMac G5 11,2

[Phileas Fogg <phileas-fogg%mail.ru@localhost>]

On 04/15/2013 08:26 PM, David Brownlee wrote:
> On 10 July 2013 13:06, Phileas Fogg <phileas-fogg%mail.ru@localhost> wrote:
> >
>
> > Quastion:
> > ----------
> > I'm not very familiar with envsys but is it possible to
> > make it control fan speed automatically depending on the current temperature
> > ? Or is it better to control fan speed in the kernel space, like
> > Linux or FreeBSD kernels do it. I would appreciate any pointers here.
> > Currently i'm doing it with a shell script which runs periodically.
> > One odd thing i noticed is that if i set e.g. all fan speeds to 1500
> > but then do not read fan rpm back for a while, SMU automatically increases
> > all fan speeds. If i read fan rpms periodically then it remains
> > at the speed which i configured last. Very odd.
>
> Could this be a watchdog like feature - so if the OS hangs and stops
> reading the fan speeds it will automatically fail over to running them
> at full speed? Sounds like quite a nice safely feature if it is....

Probably. I tested Linux and FreeBSD on the same machine and
if get a panic there or the system just lockups (which happens very
often on FreeBSD ;)) then the fans get very loud after some time.
The same behaviour can be seen on NetBSD now, so i guess it's a
hardware feature.

it's really useful i think. If my system hangs for some reason, then i 
can be sure it won't get damaged because of CPU overheating.

regards