Resurrecting mkLinux

Geert Uytterhoeven Geert.Uytterhoeven at
Wed Apr 7 18:38:52 EST 1999

On Tue, 6 Apr 1999, Dave Weis wrote:
> We got around a lot of this in the linux-ma68k port. I think these series
> of powermacs are pretty similar to the top-of-the-line 68k's. I've put
> more comments below.
> > It's not a stupid idea, but there are a handful of issue sthat would have
> > to be resolved before drivers come into play.  The biggest one is the
> > physical RAM.  On the x100 PowerMacs, RAM is not (ever) contiguous.  I
> > have some info about it in a PDF file somewhere, but not with me.  Anyway,
> > there's a table you can read to get the addresses of the banks of memory.
> > That will produce a wrinkle, if I'm reading the LinuxPPC code right, since
> > it appears to only be willing to handle a single memory region.  Also, the
> > LinuxPPC booter would have to incorporate the code to read that table, and
> > pass it in as part of the kernel boot args or whatever.  Further, since
> > the machines don't have OpenFirmware and there are substantial differences
> > between them and PCI machines, it would be wise to pass in the machine ID
> > (gestalt) along with that.  There's no reason to fake an OF tree -- it
> > would clutter the booter unnecessarily, and in virtually every place where
> > you'd do an OF check for addresses or interrupts, you'd probably have to
> > have a switch statement with a PDM case anyway, so there's not much point.
> We passed along a structure that contained addresses of ram chunks to be
> mapped.

I'm not 100% sure, but I expect Linux/PPC on APUS to handle non-contiguous
memory. APUS is just a PPC expansion for Amigas.



Geert Uytterhoeven                     Geert.Uytterhoeven at
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium

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