Re: [hatari-devel] WinUAE CPU core MMU option and CPU accuracy?

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi Nicolas,

On 11/17/2016 07:28 PM, Nicolas Pomarède wrote:
> Le 17/11/2016 à 18:23, Laurent Sallafranque a écrit :
> > I second that.
> > The falcon is a machine with a MMU, it should be enabled.
> > But maybe the timings in MMU mode are worse than in cycle exact or
> > prefetch mode.
> >
> > We should be careful with that before enabling the MMU
>
> IIRC without looking at the sources now, cpu is indeed less
> cycle-accurate when MMU mode is set.

Ok, that explains then why some programs work only with MMU,
or by disabling cycle-exactness, or using oldUAE CPU core.

This happens with...

These games:
- Boom preview
- Lasers and Hommes (needs also my Videl fix)
- Tank Blaster

And these demos:
- Bound 2
- Echoes
- Escape's "_" & "Hmmm..." demos
- Most of Lazer's demos
- Cycedelic knockout
- RH positive
- Virtual City

If I remember correctly, problem with all of them happens
right at startup.  Could you take a look at some of them?

(Last two are smallest so I would start with them)

DHS Dream Dimension has also a weird issue.  It starts fine
with oldUAE CPU core, but with WinUAE CPU core it needs
MMU to detect memory amount correctly.


	- Eero

> I guess for now MMU mode is more about running unix like OSes under
> 680x0 cpu where memory protection and all are needed, than about being
> cycle accurate to run demos/games.
>
> Maybe it could be disabled by default for falcon, I don't think many
> games/demos are using it anyway, and TOS test for MMU can be bypassed
> during boot.

??? It is disabled by default, and tests are bypassed on boot.


	- Eero
> Nicolas
>
> > Le 16/11/2016 à 21:32, Eero Tamminen a écrit :
> > > Hi,
> > >
> > > Almost all of the games & demos currently listed
> > > in compatibility doc as needing MMU with WinUAE
> > > CPU core, work also if:
> > > - oldUAE CPU core is used instead, or
> > > - CPU exact & compatible options are enabled
> > >
> > > What enabling MMU for 030 does in regards to
> > > WinUAE CPU core emulation accuracy?
> > >
> > >
> > >     - Eero