Re: [hatari-devel] SCU/VME register access?

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 04/04/2020 à 16:42, Eero Tamminen a écrit :
> Hi,
>
> Currently Hatari allows emulated code to access MegaSTE & TT SCU/VME 
> registers without exceptions,
> although Hatari doesn't actually emulate those
> registers.
>
> Based on code comment, this is done for TOS
> (2.x I assume) to be able to recognize MegaSTE.
> But there's no comment on why it's allowed for TT.
>
> Linux tries to use those registers if they're
> accessible, and will fail to boot under MegaSTE
> and TT emulation because of that.
>
> I've added patch to Hatari which can be used to
> make this register access build-time configurable:
> https://git.tuxfamily.org/hatari/hatari.git/tree/tools/linux/hatari-vme-access.patch 
>
>
> (With them being accessible by default.)
>
> Would it be OK to commit that change to Hatari,
> instead of just having it as a separate patch?
>
>
>      - Eero
>
> PS. SCC registers were earlier also a problem, but
> not anymore as Hatari emulates them now.  However,
> I don't see SCU/VME register getting emulated any
> time soon.

Hi

instead of making these registers configurable at build-time, I'd rather 
we go through the specs of the megaste / tt and see which registers 
exactly should be emulated on both machine and whether they cause a bus 
error or not.
I'm not very fond of having different build options that require the 
user to know how the HW behave. HW behaviour should be known in Hatari code.

Nicolas