NAP mode on powerpc 970

Benjamin Herrenschmidt benh at
Tue Jan 20 08:50:39 EST 2004

> On the G5, how does the OS have knowledge if it needs to go into NAP
> mode or not?  From my understanding, going in and out of NAP mode causes
> power spikes and there are some unknown thermal implications on the
> CPU.

I just do it on idle loop like with any previous G4 or G3 CPU, it
appears to work fine. Do you have some documentation about the possible
issues ? I didn't catch anything special in the Darwin code regarding
use on NAP mode neither, it seem to be used normally there as well.

> When I talked to the HV team, they do not want to do this solution.
> They are leaning towards another alternative, or having it done in FW so
> the change does not need to be done in multiple places (e.g. Different
> linux distros, and AIX).

No comment...


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