Re: Antwort: Re: blizzppc.device and NetBSD 1.3.2

[Alexander Pokahr <alex%reftools.de@localhost>]

Hi there,

as noone has answered this yet, i'll make a try, but please note, that
i'm not that much into the PowerUp internals, so i may be wrong
in some of this. If anyone knows it better please correct me.

>How different is a PPC Amiga from a normal one? Is it just an Amiga with a
>totally different CPU (I know how the PPC instruction set looks like, I once
>read the 601 reference manual briefly when I saw it in a library) or is it
>to be considered a completely new machine? 

Yes, it is a new machine, housing in your Amiga, but it's far from being
complete ;).
The PowerUp-board is just a PPC-processor, some RAM, and the PowerUp-kernel-
software, which is the PowerUp-OS, and is different from the AmigaOS.
The PowerPC is not able to access the DMA-RAM (Chip-RAM), so it is not
possible to adress the custom-chips. It might even be impossible for
the PowerPC to adress the Zorro-bus, but i'm not sure of this.
For input/output things, the PowerUp-kernel messages a task, that runs
on the 680x0, to do the necessary things. These are handled by the
ppc.library, that runs on the AmigaOS.

So, if you want to port NetBSD to PowerUp, you will have to write
two kernels! One, that runs on the PowerPC, and one, that runs on
the 680x0.

Maybe it is possible to use the ppc.library, and only to write a
PowerPC-kernel. This would mean NetBSD to take over the PowerPC
(and disabling the PowerUp-kernel), but still having the AmigaOS
running on the 680x0, and doing the input/output for NetBSD.
But this may be even worse to implement.

AFAIK there is a beta-state linux-ppc kernel for PowerUp, but i havent
tested it, and dont know, how it works. But if anyone is interested
in doing a PowerUp port of NetBSD, he should have a look at it.

CU,

Alex

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| Alexander Pokahr |        (o o)
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