recent FreeBSD 13.0-CURRENT has fans screaming again on PowerMac quad

[Mark Millard]

On 2020-Jun-19, at 09:10, Justin Hibbits <chmeeedalf at gmail.com> wrote:

> On Fri, 19 Jun 2020 15:57:43 +0000
> Dennis Clarke <dclarke at blastwave.org> wrote:
> 
>> . . .
>> 
>> Now then, how do I get you the details you need about hardware?
>> 
>> . . .
> 
> Providing the output of 'ofwdump -ap' will suffice.

Last I knew this command crashes modern, official powerpc64
FreeBSD on PowerMacs (without usefdt mode in use). Back when
I could boot official 32-bit powerpc FreeBSD on the 64-bit
hardware, that would let me run the ofwdump -ap command.
(I've not tried 32-bit in some time but last I tried it did
not work.)

The crash was for a kernel DSI read trap and was tied to the
dmap addressing changes mixed with executing openfirmware code
when a page ended up not mapped and openfirmware tried to
handle it. (This is from memory.) Details are listed in:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237590

The bugzilla comments report that the failure was during
"OFIOCGET for the fairly large log property". If I remember
right the example was a PowerMac11,2 Quad but the
Powermac7,2 also failed.

> The 'model'
> property listed at the top will tell you what the type is.  The rest
> will help for figuring out what is needed.  However, I know already
> that since you have a Quad, it's a PowerMac11,2 so I don't need more
> details.
> 
> All I gleaned so far from the Linux source was that PowerMac11,2 and
> PowerMac (G4 family) use GPIOs for timebase enable, while PowerMac7,3
> uses i2c twiddling, which looks more complicated.  Given the age of
> that hardware, I'm inclined to punt on that one, and get the
> low-hanging fruit, which should satisfy most users.
> 

FYI: I sometimes have access to a PowerMac7,2 (dual socket, 1 core each)
and should be able to test there --if 7,2 is relevant.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)