Re: [hatari-devel] Hatari hangs with NVDI when MMU is enabled

[Uwe Seimet <Uwe.Seimet@xxxxxxxxx>]

Hi,

I'm sorry, I missed something. NVDI works now with only the PMMU option
enabled, but ROMSPEED does not, it crashes with a bus error.

Best regards

Uwe

> Hi,
> 
> > I reproduced the issue seen by christian, after some debugging / 
> > tracing, the problem is that cache state was not consistent in the case 
> > of 68030 + mmu with more_compatible=off and cycle_exact=off.
> > Some functions were accessing memory through the data cache, other were 
> > not, so in the end the value written to change trap's vector was not 
> > seen by the exception handler :(
> > 
> > After discussing with Toni, this options' combination is in fact not 
> > valid : data cache emulation requires either more_compatible or 
> > cycle_exact, so if none are set, data cache emulation should be disabled
> > 
> > The problem would the same with 68030 and no mmu, but in that case the 
> > code path is different and data cache is not used by cpu emulation even 
> > if it was enabled, which explain why there was no crash.
> > 
> > Change was committed to disable cache when necesary, with or without MMU.
> > 
> > Please, test if NVDI works better now.
> 
> I'm afraid there is no change. When I switch on PMMU support only (no
> prefetch, no cycyle exact) NVDI still hangs. Maybe I misunderstand what
> you wrote above, but just PMMU only should work now, shouldn't it?
> 
> I have to admit, I do not understand why these options are not
> independent, and why enabling the PMMU and *either* cycle exact *or*
> prefetch changes the behavior. This sounds like an intransparent
> side-effect to me
> 
> Best regards
> 
> Uwe
> 
>