[OpenBIOS] [Qemu-ppc] FreeBSD powerpc issue

[Andreas Tobler]

Hi Alex!

On 26.08.12 06:24, Alexander Graf wrote:

>> get_bat: IBAT v fff025a4
>> get_bat: IBAT0 v fff025a4 BATu 00001ffe BATl 00000012
>> get_bat: IBAT1 v fff025a4 BATu 00000000 BATl 00000000
>> get_bat: IBAT2 v fff025a4 BATu 00000000 BATl 00000000
>> get_bat: IBAT3 v fff025a4 BATu 00000000 BATl 00000000
>> no BAT match for fff025a4:

And about this one I do not have to worry?

>> get_bat: IBAT0 v fff025a4 BATu 00001ffe BATl 00000012
>> 	00000000 00000000 0ffe0000
>> get_bat: IBAT1 v fff025a4 BATu 00000000 BATl 00000000
>> 	00000000 00000000 00000000
>> get_bat: IBAT2 v fff025a4 BATu 00000000 BATl 00000000
>> 	00000000 00000000 00000000
>> get_bat: IBAT3 v fff025a4 BATu 00000000 BATl 00000000
>> 	00000000 00000000 00000000
>> Raise exception at fff025a4 => 00000003 (40000000)
>
> This means that at address 0xfff025a4 we hit a
>
>      POWERPC_EXCP_ISI      = 3,  /* Instruction storage exception             */
>
> with flags
>
> 33
> Set to 1 if MSR.IR=1 and the translation for an attempted access is not found in the Page Table; otherwise set to 0.
>
> So something was trying to jump to code that is not mapped in the HTAB. The address is definitely an OpenBIOS address, so for some reason FreeBSD messed with the HTAB, didn't make sure that OpenBIOS is still mapped in and then jumped to it. I wonder why the code works on real hardware?

Aha, this gives me a challenge to find out what is happening.
It works on real hw, but from my observation it sometimes 'hangs' and to 
find out about this issue I started to play with qemu ;)

Thank you very much.

Now I have to find out about why the OpwnBIOS area is not mapped.
Is it the case that the 'of' code on Apple HW is located elsewhere, not 
on such high address like 0xfff00000? Or should that not matter?

Andreas