[OpenBIOS] [Qemu-ppc] Running client with MMU off

[BALATON Zoltan]

On Wed, 25 Jun 2014, BALATON Zoltan wrote:
> ppc_store_sdr1: 0fe00000
> helper_store_sr: reg=0 20000400 00000000
[...]
> helper_store_sr: reg=0 00000000 20000400
> Raise exception at 0041cd00 => 00000003 (40000000)
>
> ^^^ This exception should not happen. It is trying to handle it but the 
> handlers are not working yet and gets in an infinite loop. It boots if MMU is 
> disabled while this part runs but MorphOS does not disable it yet and 
> according to my oftest results they are enabled on Apple too. How does it 
> work on real hardware and why does it fail on QEMU? (Note the the value of 
> sr0 is identical to the one set by OpenBIOS and SDR1 is unchanged so 
> translations via the page table should still work, shouldn't it?)

I was mistaken about the values being the same as it is zeroing sr0. So 
can this explain why translation via the page table fails after this and 
why an ISI is generated? Why are the sr registers set up with the values 
above by OpenBIOS? Could they be 0 instead?

Regards,
BALATON Zoltan