Re: [hatari-devel] Adding cache support for the MegaSTE -> DONE

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 04/09/2024 à 14:26, Cyprian Konador a écrit :
> On Tue, 3 Sept 2024 at 23:12, Nicolas Pomarède wrote:
>
>     Hi
>
>     as a summer job, I worked on supporting the MegaSTE external 16 KB
>     cache
>     in Hatari :)
>
>
> great news. Many thanks
>
>
>
>     Note that the cache needs to be flushed on every transfer when using
>     Gemdos HD emulation, or normal FDC / HDC. Else this would transfer data
>     to RAM without invalidating the cache (which has no means to know RAM
>     has been modified), thus creating crashes in the emulated program
>     sooner
>     or later.
>
>
> I heard that the Mega STE cache is automatically flushed by the BLiTTER 
> activity. I wonder if  FDD/HDD DMA behaves the same (as both are on the 
> same the CPU BUS)

I don't have a MegaSTE to check it myself, but according to chistian the 
cache is flushed on :
 - reset
 - bus error
 - blitter and more generally changing bus ownership (so fdc/hdc dma too)

Hatari handles these cases

Nicolas