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

From: Mark Cave-Ayland
Subject: Re: [Qemu-ppc] MorphOS 4.x on QEMU
Date: Thu, 27 Feb 2014 22:25:06 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130116 Icedove/10.0.12

On 26/02/14 02:43, 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?

Hi Zoltan,

Sorry I am around, just exceptionally busy at the moment. My efforts around QEMU/OpenBIOS are unsponsored and so get relegated into whatever spare time I have left :)

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.

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.

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.

Any ideas anyone?

When I last spoke with the MorphOS guys, I did manage to talk to someone on IRC who had the source code open on his machine and would give me pointers in the right direction as to roughly what the bootloader was doing. I suggest that you'll need to ask in the forums/mailing lists/IRC to see if someone is willing to help you at all.

FWIW there is a known issue with PPC's next-property iterator being implemented differently to the standard (see Olivier's tentative patch at http://www.openfirmware.info/pipermail/openbios/2014-February/008141.html). It's likely that a broken device tree iteration could be the cause of the MorphOS bootloader not being able to locate a suitable console mode which could be related to your issue.

Also on SPARC there were problems with the hardware flow control causing serial console output from the Solaris kernel to freeze; the eventual solution was to add properties to the serial port node which tell the kernel to ignore the hardware flow control lines.



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