Re: [hatari-devel] Tests of Falcon games

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

Games using MMU to remap memory areas is a possibility, but how Capy 
could then have
worked with earlier Hatari version when MMU
is *disabled*, unless Falcon bus mode was also
broken with previous Hatari release?

Nicolas, what's the best way to debug whether and
what kind of MMU operations a program does?


	- Eero

On 10/6/20 11:26 PM, Laurent Sallafranque wrote:
> Would it be possible
>
> Le 06/10/2020 à 00:48, Eero Tamminen a écrit :
> > Hi,
> >
> > On 10/5/20 11:20 PM, Nicolas Pomarède wrote:
> > > Le 04/10/2020 à 18:59, Eero Tamminen a écrit :
> > > > > capy : not tested
> > > >
> > > > Dies now to:
> > > > WARN : Bus Error reading at address $ff9c00, PC=$3dfe2 addr_e3=3dfe2 
> > > > op_e3=4cd8
> > > >
> > > > This is *regression* from Hatari v2.2.1.
> > > >
> > > > (FF9C00 is just after normal VIDEL regs.)
> > >
> > > > > Sokoban by FUN : game freeze (black screen) after Bus Error writing 
> > > > > at address $ff97fe, PC=$e12bce addr_e3=e12bce op_e3=4ad5
> > > >
> > > > same.
> > >
> > > according to our test results for bus errors in falcon mode, we can 
> > > see that we have different results depending on compatibility mode 
> > > with ste (bit 5 at ff8007).
> > >
> > > in falcon mode :
> > >   $FF9C00 - $FFA200 : gives bus error
> > >   $FF9224 - $FF9800 : gives bus error
> > >   -> access to ff9c00 and ff97fe should give bus error
> > >
> > > in compatible mode :
> > >   $FF9000 - $FFA000 : no bus error
> > >   -> access ff9c00 and ff97fe should not give bus error
> > >
> > > So, are those games really supposed to run in plain falcon mode or 
> > > should compatible mode be used ?
> > > I don't see why the games would access these 2 addresses that don't 
> > > seem to be used for anything.
> >
> > When tracing the compat bit:
> > b (0xff8007).b & 0x20 ! (0xff8007).b & 0x20 :trace
> >
> > It seems to be set (= Falcon mode) at boot, before
> > TOS memory test.
> >
> > Neither of these games clears that bit to STE bus
> > mode.
> >
> >
> > With current Hatari, Capy works if MMU is enabled [1], fails if MMU is 
> > disabled. With earlier Hatari
> > version, it worked regardless of whether MMU was
> > enabled or not.
> >
> > (Which is confusing... Didn't the Falcon bus mode
> > work properly earlier?  If it now works correctly,
> > how this game ever worked on real Falcon them?)
>
> Isn't it possible that the game remaps some falcon memory areas with the 
> MMU to avoid the bus adressses ?
>
> After all, we've done all our previous tests with MMU off, but as it 
> improved a lot these months, I've decided to test with MMU = ON (as it 
> is in the real Falcon).
>
> Laurent