Re: [Qemu-devel] AmigaOS 4.x on QEMU

[BALATON Zoltan]

On Sun, 12 Jan 2014, Alpha Mule wrote:
> Hi. AmigaOS 4.x runs natively on some niche PowerPC boards. I was
> wondering about the viability of running AmigaOS 4.x on QEMU.
>
> Specifically, I was wondering if there has been any development on
> that and/or what needs to be done to get it fully working.
>
> Any information would be appreciated. Thanks.

Looks like not much info is available on this... I think that the first 
difficulty is that AmigaOS 4.x is not freely available (AFAIK) so it's 
hard to do any testing with it.

I've found that a demo version of MorphOS (which is not the same but runs 
on similar hardware) is available and runs on some Mac hardware that may 
be closer to what qemu already has support for so it may be an easier 
target to test.

I've tried to boot it on qemu but haven't got very far and I think qemu is 
missing some features MorphOS needs so it may not be easy to make it work. 
Here's what I've found:

1. The CPU type MorphOS seems to prefer is G4 7447A. This CPU type may not 
be fully supported by qemu yet and specifying it with -cpu makes the VM 
hang in the openbios firmware before it even gets to boot the OS. By using 
the default G4 CPU without any -cpu option it gets further and hangs later 
in the OS's boot loader.

2. None of the video cards MorphOS can work with is emulated by qemu and I 
think those qemu has do not work with MorphOS. So even if it was running 
otherwise there would be no display. Theoretically this may be got around 
(for testing at least) with the PCI pass-through of an appropriate card 
from the host but I don't have such a video card at hand and don't know if 
this would be possible in practice at all.

3. The farthest I got is with the 'boot cd:,\mac_ppc32\boot.img' command 
line from openbios which seems to at least start to boot but hangs without 
any messages (even on the serial console) quite early and I don't know 
enough to debug this further. All I got was some debug logs which seem to 
go astray around here:

IN:
0x00441b14:  dcbtst  r8,r10
0x00441b18:  stw     r5,4(r10)
0x00441b1c:  stw     r5,8(r10)
0x00441b20:  stw     r5,12(r10)
0x00441b24:  stw     r5,16(r10)
0x00441b28:  stw     r5,20(r10)
0x00441b2c:  stw     r5,24(r10)
0x00441b30:  stw     r5,28(r10)
0x00441b34:  stwu    r5,32(r10)
0x00441b38:  bdnz+   0x441b14

Raise exception at 00441b18 => 00000002 (00)
invalid/unsupported opcode: 00 - 00 - 00 (00000000) 00000080 0
IN:
0x00000034:  addi    r1,r1,16
0x00000038:  lwz     r0,52(r1)
0x0000003c:  mtlr    r0
0x00000040:  lwz     r0,56(r1)
0x00000044:  mtcr    r0