Re: [Qemu-ppc] MorphOS 4.x on QEMU

[Alexander Graf]

BALATON Zoltan wrote:
> On Tue, 25 Feb 2014, BALATON Zoltan wrote:
>> On Tue, 25 Feb 2014, BALATON Zoltan wrote:
>>> overwrites part of the exception_return code of openbios so the next
>>> time it gets a DSI exception and is trying to run this code it leads
>>> to an invalid opcode exception and that's it.
>>
>> Actually if I restore the overwritten word in memory it runs further
>> until it prints "console failed".
>
> Hmm... Does anyone actually reads this list or am I talking to myself
> here?

I'm fairly sure most people don't particularly have a good idea what's
going wrong for you :).

>
> Debugging it further shows that despite not finding a compatible
> Radeon graphics adapter it continues further and only stops after
> trying to identify/initialise the CPU.  I still have no fix for the
> zeroing the 0x80 address causes an exception problem.

That's probably a NULL pointer exception. Your bootloader is trying to
find something, doesn't find it, returns NULL, something else takes the
return value as granted and accesses that pointer + 0x80.

> Is is possible to use pci passthrough to make a graphics card
> available to the guest? Was it tested recently on ppc? Is there any
> documentation on how to do it? In case I can find a compatible card I
> might try to see if that would work.

So far PCI passthrough has only been done on IBM POWER (-M pseries) and
Freescale e500  (-M ppce500) systems. I doubt MorphOS runs on either of
them. Plus PCI passthrough is pretty hard to get right with TCG - so
this is something I don't think anyone attempted so far.

If you like to give it a go though, try to make something slightly more
simple work first though :). VGA adapters are hell.

>
> Also I've found that the MorphOS kernel looks for a device within /pci
> with a class-code == 0x0780 (other communication device) for a serial
> port where it may display some debug info. Unfortunately there is no
> such device on QEMU. Is there an easy way to add one? Can someone
> verify if this is present on Mac hardware or does it expect some third
> party serial card for debugging? Having some debug printout might help
> debugging this further.

There's a web page somewhere with lots of device tree dumps from systems
all over the place. I don't have the link right now, but I'm sure Google
knows more :).


Alex