Re: [hatari-devel] Disk driver memory access checks

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 13/10/2018 à 18:53, Uwe Seimet a écrit :
> > if transfer is made using DMA, does DMA generate bus error when trying
> > to write to TOS ROM or is this not handled at all and "ignored"
> > (contrary to what would happen if the cpu try to write to ROM)
> >
> > One could test this on real HW by just using xbios to read a floppy
> > sector into ROM.
>
> Assuming that the DMA chip generates a bus error in such a case, what's
> the most similar approach in the case of nf_scsidrv? Just returning an
> error code as a result of the ST memory check probably not.
> Of course, I'm aware that this is a rather esoteric problem.

I would need to check in the code how to raise a bus error from outside 
the cpu emulation ; in the meantime, the safest is just to ignore writes 
to ROM (ie : considerer all the data were transfered but ignore the writes)
A you say, it's a corner case and we wouyld need to check on real HW 
first the behaviour for DMA FDC and for other DMA in TT/Falcon

Nicolas