[OpenBIOS] [Qemu-ppc] FreeBSD powerpc issue

[Alexander Graf]

On 26.08.2012, at 12:09, Segher Boessenkool <segher at kernel.crashing.org> wrote:

>>>> Phew. I honestly have no idea how this would work at all even on
>>>> Apple HW. Linux simply handles everything from real mode (disable
>>>> paging) when going into anything firmware related. I have no idea
>>>> what OpenBSD does. If you could try to find out and summarize it, I
>>>> might be able to reconstruct how it could work :).
>>> 
>>> Perhaps the OpenBSD code did not flush the TLB yet?  Or does QEMU
>>> emulate the TLB properly?  I seriously doubt that :-)
>> 
>> Hm, s/OpenBSD/FreeBSD. :)
> 
> I have no idea :-)
> 
>> How do I flush the TLB?
> 
> tlbie, and perhaps tlbsync.

The QEMU TLB only caches existing translations, never misses.

Alex

> 
>> Then I can look up in the code and see where it is done. I guess we do that but the place/time might be the question.
>> (Otherwise it wouldn't work on real HW, right?)
> 
> That is my theory, yes.
> 
>>> The logs do not show whether segment x'f is still mapped in the
>>> SRs (or I missed it).  Is it?
>> 
>> How can I enable this log or make it visible?
> 
> I have no idea.
> 
> 
> Segher
> 
>