Re: [hatari-devel] VME access

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

This is a multi-part message in MIME format.

Hi,

Attached is new patch.

On 1/3/21 3:16 PM, Thomas Huth wrote:
> On 03/01/2021 12.24, Eero Tamminen wrote:
> > On 1/3/21 12:33 PM, Thorsten Otto wrote:
> > > On Sonntag, 3. Januar 2021 10:02:19 CET Thomas Huth wrote:
> > > >   Couldn't you please try to come
> > > > up with enough VME emulation instead to fix Linux on the TT?
> >
> > Thomas, it's about interrupt handling and based on
> > comments seems to e.g. redirect FDC interrupts:
> > https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/tree/arch/m68k/atari/config.c#n394 
> >
> > VME interrupts are set here:
> > https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/tree/arch/m68k/atari/ataints.c 
> >
> > And up to 16 VME interrupts are supported:
> > https://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/tree/arch/m68k/include/asm/atariints.h#n24 
>>
> > I could add some pre-liminary code to setup
> > suitable SCU mask etc variables when corresponding
> > regs are written...
> >
> > But I'm unfamiliar how the whole Hatari interrupt
> > handling works, and with need to reroute existing
> > interrupts to go through SCU that's something
> > I'll leave to you or Nicolas.
>
> At least I also don't have any clue about SCU interrupts either, so it's 
> learning by doing - if you never try, you'll never get into it :-)

Well, there's pretty little documentation about that. I've found some 
notes from "Atari TT030
Hardware Reference Manual", but I think one
should really understand interrupt handling
for it to be enough (which I don't).

Weirdly, TOS v2 & v3 seem to crash unless SCU general purpose reg has 
value (1) on boot,
although docs say that SCU regs are cleared
on boot.


> > "--vme <x>", where <x> is:
> >    "none" - VME reg access causes errors
> >    "dummy" - what's currently done, errors disabled
> >
> > And in future:
> >    "empty" -- VME interrupts working, no VME card
> >    "net" -- VME network card emulation
> >
> > Thomas, does that sound any better?
>
> Ok, yes, still not my favorite solution, but looks certainly a little 
> bit nicer, so I guess I could live with it. I'd maybe also omit the 
> config file saving/loading as long as there is no entry for this in the 
> GUI yet (otherwise people might end up with a wrong setting in their 
> config file at one point in time and then wonder why things are not 
> working anymore as expected when they later run without the --vme 
> parameter).

Attached patch does this and adds dummy functions
for all the regs with new VME trace output.


	- Eero