Adding PMU support for Apple PPC-based computers

[Bruce Cran]

Philip Schulz wrote:
> Hi,
>
> Am 31.10.2007 13:30, bruce at cran.org.uk schrieb:
>> I recently installed FreeBSD 7.0-BETA1 on my 1GHz G4 iBook.  I got it
>> installed without too many problems, but noticed that it's only running
>> at 356MHz - from reading previous posts I gather it's because FreeBSD
>> doesn't support the PMU, which needs programmed to take the CPU up to 
>> its
>> full speed.  Is anyone already working on this, or is it something I
>> could take a look at to see what would need done to support it?
>>
>
> NetBSD has a new, polished driver for the PMU that is in my 12" 
> PowerBook G4. I don't know if it touches the CPU divider, though (*) 
> What certainly works on my PowerBook is using the "set-dfs-high" word 
> in the CPU node of Open Firmware:
>
> > dev /path/to/cpu
> > set-dfs-high
>
> I don't know if your laptop has that word, but you can easily find out 
> by typing "words" once you've navigated to the CPU node.
>
> HTH,
>
> Phil.
>
> (*) I've done a quick and dirty port of that driver to FreeBSD for a 
> project I'm working on, but the code is not nearly in shape to be 
> released to the public. I haven't been able to work it for a while 
> now, but I might be able to polish it up a bit and file a PR.
>

Thanks - my iBook does have the set-dfs-high word; I spent some time 
learning OpenFirmware a few months ago and found that after using 
set-dfs-high the system booted at around 550MHz.  I've just installed 
7.0-RC1 and found that it boots at 550MHz without using set-dfs-high: if 
I do use it the system now boots at the top speed of 1GHz.

--
Bruce