2002-09-25 23:47:53

by Richard Drummond

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Subject: Kernel and Open Firmware problems with my G3 upgrade card


Not sure whether this is the right place to ask these question, but I've been
searching for some answers for a while, and - because part of the problem is
kernel-related - I'm gonna ask here anyway.

I upgraded my Old Word Mac recently (a Starmax Tanzania-based machine) with a
[email protected] G3 card. This is the type of expansion that plugs into the cache RAM
socket. It seems to be stable under Linux, but there are a few nagging

1. The machine will no longer boot with Quik. It fails with one of those nasty
DEFAULT CLAIM messages, and the usual OF hack to wait for disk spin-up makes
no difference. To use Linux, I now have to boot MacOS and start Linux via
BootX - which is a pain.

2. The Kernel doesn't recognize this G3 processor properly. It claims the
clock speed is 80MHz, when actually it's 260MHz; and it claims that the L2
cache's size is 256K, when actually it is 512K. (Output from /proc/cpuinfo on
kernel 2.4.19 attached.)

I suspect these problems are related and are due to the fact that the version
of Open Firmware in this machine was never designed to handle a G3 processor
and so the L2 cache doesn't get set up properly. Interestingly, OF reports
the CPU as a PowerPC,608 and there's no L2CR property present at all. I'm
guessing the Quik booting problem is due to the improperly set-up cache
interfering with disk access. The reason Linux boots from MacOS is that the
MacOS extension for this card sets up the L2 cache correctly, and so lets
BootX load the kernel.

My questions are:

Is there some way to set the L2CR from OF - bearing in mind there's no l2cr
property in OF's CPU node? (BTW, the cache control utility under MacOS, whose
name escapes me, reports the L2CR's contents as 0xA910000.)

Would be it feasible to modify the kernel to properly recognize the processor
on this card? (I suppose setting up the L2CR properly would at least get it
to report the cache size correctly. But what about the clock speed?)

Any suggestions, anybody?


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