[OpenBIOS] [Qemu-ppc] Debug logs for USB on MorphOS

BALATON Zoltan balaton at eik.bme.hu
Mon Nov 21 01:01:16 CET 2016

On Fri, 11 Nov 2016, BALATON Zoltan wrote:
> For those interested in more details it seems that the pciusb.device driver 
> finds the OHCI chip in QEMU but does not like it and does not claim or try to 
> initialise it for some reason.

It wasn't too easy to find it but it turned out to be caused by a mismatch 
between what's emulated in QEMU and what OpenBIOS put in the device tree 
so when trying to access the config registers of PCI bus 1 MorphOS ended 
up using PCI bus 0 which of course returned an error. After this was fixed 
the USB controller is found but patches from BenH to fix the interrupt 
was also needed for it to work. Patches submitted to OpenBIOS and QEMU.

> The usefulness of this activity may not be direct as MorphOS may not ever run 
> on) but the bugs found and fixed during this do help making the device models 
> in QEMU more accurate and help running other OSes. I think some of the bugs 
> fixed this way in OpenBIOS and QEMU also helped to get MacOS running so I 
> like to believe there are at least some indirect usefulness of this.

MorphOS now has input but still lacks some way to output video (this still 
needs some work). But if other OSes had the same problem fixed here then 
this may fix the enabling of the bus master bit for some network cards so 
the patch added for that in OpenBIOS may not be needed now and fixing the 
interrupt may improve mouse or sound behaviour on MacOS. I haven't tested 
these, just verified that MacOS 9 and Linux still boots with these patches.


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