Re: [hatari-devel] Valid memory amount?

[Eero Tamminen <oak@xxxxxxxxxxxxxx>]

Hi,

On 11/19/20 10:48 AM, Nicolas Pomarède wrote:
> Le 18/11/2020 à 23:49, Eero Tamminen a écrit :
> > > > Btw. 10MB is supported on MegaSTE & TT, but
> > > > not on Falcon.  Specific memory amounts are
> > > > enforced (with a warning) only for Falcon though.
> > > > I wonder should they be enforced also for others?
> > >
> > > I assume you are talking about the STMemory_CorrectSTRamSize()
> > > function? ... I guess yes, maybe it should be enforced for these
> > > machines, too, but that's certainly a change that should rather wait
> > > until the release has been done.
> >
> > Would the attached patch be acceptable before release?
>
> no please, not so close to release, I don't consider this a regression ; 
> RAM amount might not be correct for all possible machine (or not ?), but 
> we're not sure and it's not the time to change it again.

It only changes memory handling for Falcon, by
rounding up also smaller memory amounts to
something that is actually supported.  Rest is
just making the memory limit code more readable /
documented.

Falcon changes prevent following errors with TOS4:

* 128KB: freeze
* 256KB: thousands of address + double bus errors

(EmuTOS boots with 256KB, but doesn't work
otherwise.)

And because 640KB is recognized by TOS as 512KB,
it's kind of redundant to support as-is for
Falcon, so that's rounded up to 1024KB.


2176KB & 2560KB amounts are already with current Hatari code rounded up 
to 4MB on Falcon boot.


> Let's write a doc that summarizes everything (not just in the .c files) 
> and tells for each machine which amount of RAM was possible (natively or 
> with more or less complex HW addons).
>
> Once we have such a doc, we can do the needed changes, if any (after 
> release)


	- Eero