[hatari-devel] A few more issues before v1.5

[Nicolas Pomarède]

Le 13/04/2011 22:23, Laurent Sallafranque a écrit :
> Hi,
>
> Same for me :
>
> M68000 Bus Error reading at address $ff8e21.
> M68000 Bus Error writing at address $ff8e21.
> Bus error lput at 4e7340e3
> Bus error wput at 4e7340e1
> Bus error wput at 4e7340d9
> Bus error lput at 4e7340db
> Bus error wput at 4e7340df
> Bus error lput at 4e7340e3
> Bus error lput at 4e7340d5
> Bus error wput at 4e7340d3
> Bus error wput at 4e7340cb
> Bus error lput at 4e7340cd
> Bus error wput at 4e7340d1
> Detected double bus error at address $4e7340d5, PC=$3e00ca2 => CPU halted!
>
>
> Laurent

The problem is that this program is trying to save/restore the content 
of $ff8e21. This register is only available on mega ste and control the 
mega ste's cpu cache/freq.

MOVE.B $ffff8e21,$000354f8

Reading this address on a non mega ste will return a bus error, which is 
normal (and is handled by the program). But in the case of Hatari we 
still write $ff into $ff8e21, but I don't know what is the good behaviour :

  - write nothing into $354f8, since the intruction is interrupted by 
the bus error (in that case $354f8 remains 0, which is good)

  - write something into $354f8 (as we do now), but this would mean that 
reading in unused IO region would return something different from $ff 
(which is usually the case)

I would think the first case need to be applied, motorola docs are 
saying the current instruction is immediatly stopped, so the write 
access should not occur (I would need to check this on a real ST, but 
this is also what Steem is doing).

I will try to fix this with some other things I'm working on, could take 
1 or 2 weeks as I will be away for a few days.

Nicolas


>
> Le 13/04/2011 21:42, Eero Tamminen a écrit :
>> Hi,
>>
>> Does tymewarp work for somebody:
>> http://www.pouet.net/prod.php?which=15943
>> ?
>>
>> It crashes to double bus error before I get to songs.
>>
>>
>> - Eero