[OpenBIOS] [Qemu-ppc] Running client with MMU off
BALATON Zoltan
balaton at eik.bme.hu
Thu Jun 26 13:36:57 CEST 2014
On Thu, 26 Jun 2014, Alexander Graf wrote:
> On 26.06.14 13:20, BALATON Zoltan wrote:
>> On Thu, 26 Jun 2014, Alexander Graf wrote:
>>> You could enable write protection on the first page before you enter the
>>> payload. Then you could unprotect it and disable interrupts as soon as
>>> someone wrote to it. I guess that'd be a pretty solid hack.
>>
>> Good idea, I'll look into this. But 0x00-0xff is reserved for operating
>> system use and MorphOS does write to 0x80 before touching the vectors
>> (that's why I can't just check from the DSI handler). Can I selectively
>> enable writes on a write protected page? (I'll need to read about it some
>> more.)
>
> Not easily. You could emulate the 0x80 write maybe. Is it too early if you
> just disable DR/IR on the 0x80 touch?
Definitely too early as this is the first thing it does.
> I don't think any other OS really accesses these ranges, but only time
> will tell ;).
Don't know, according to previous replies they may. Then how about always
clearing the translation for page zero the next time our handler is called
so I always get a new exception when it's accessed? (I have to add it for
the access to succeed but I may remove it at the next possible occasion.)
In the lack of a better idea I'll try this.
Regards,
BALATON Zoltan
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