Re: [hatari-devel] Hatari/TT VME adress space behavior

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 08/07/2025 à 10:14, Nicolas Pomarède a écrit :
> Le 08/07/2025 à 10:12, Uwe Seimet a écrit :
> > Hi,
> >
> > > although some changes for SCU support can be seen as related to the VME
> > > bus and its registers, Hatari does in fact very little regarding VME
> > > itself, so it's quite possible it doesn't behave similarly to a real TT
> > > as you describe.
> > >
> > > But using reports as yours comparing real TT to emulation, it should be
> > > possible to improve this, especially returning bus error should not be
> > > too difficult (as Hatari doesn't support VME card emulation)
> >
> > Any chance to get this implemented/fixed? After looking at the sources I
> > do not know how to do this, but maybe for somebody who has more 
> > insight it
> > is just a minor effort?
>
> Hi
>
> it seems I lost track of this mail after the discussion went on DKIM / 
> mails problem.
> I will add this to my todo list

Hi

can you try the attached patch on top of the current git devel version 
of hatari ?

it should return bus error when accessing $FExxxxxx regions in MegaSTE 
and TT mode.

Nicolas

diff --git a/src/cpu/memory.c b/src/cpu/memory.c
index c60d8bdb..2cbd8590 100644
--- a/src/cpu/memory.c
+++ b/src/cpu/memory.c
@@ -47,6 +47,8 @@ static uae_u32 TTmem_mask;
 #define IOmem_start  0x00FF0000
 #define TTmem_start  0x01000000			/* TOS 3 and TOS 4 always expect extra RAM at this address */
 #define TTmem_end    0x80000000			/* Max value for end of TT ram, which gives 2047 MB */
+#define VMEmem_start 0xFE000000			/* MegaSTE and TT support a VME bus. This returns a bus error */
+#define VMEmem_end   0xFF000000			/* when no board is plugged */
 
 #define IdeMem_size  65536
 #define IOmem_size  65536
@@ -1813,6 +1815,13 @@ void memory_init(uae_u32 NewSTMemSize, uae_u32 NewTTMemSize, uae_u32 NewRomMemSt
 		map_banks_ce(&BusErrMem_bank, IdeMem_start >> 16, 0x1, 0, CE_MEMBANK_CHIP16, CE_MEMBANK_NOT_CACHABLE);
 	}
 
+	/* VME region on MegaSTE and TT : 0xFE000000 - 0xFEFFFFFF */
+	/* Hatari doesn't emulate VME board for now, so this region should return bus errors */
+	if ( Config_IsMachineMegaSTE() || Config_IsMachineTT() )
+	{
+		map_banks_ce(&BusErrMem_bank, VMEmem_start >> 16, ( VMEmem_end - VMEmem_start ) >> 16 , 0, CE_MEMBANK_CHIP16, CE_MEMBANK_NOT_CACHABLE);
+	}
+
 	/* Illegal memory regions cause a bus error on the ST: */
 	map_banks_ce(&BusErrMem_bank, 0xF10000 >> 16, 0x9, 0, CE_MEMBANK_CHIP16, CE_MEMBANK_NOT_CACHABLE);