Re: [hatari-devel] EKO system regression

[Laurent <laurent.sallafranque@xxxxxxx>]

Could another approach be to add an "advanced" section in the Hatari GUI 
parameters ?

Something like "use the cardridge port" if checked and "use the gemdos 
HD" if not or something like that.


I second Nicolas : many people will use hatari to look at demos, games 
and/or use old tools.

And a demo like EKO System is a master piece of code for the falcon.

It would be bad to loose it for a new option, any good and useful it is.


It's only my 5 cents to the question.

Regards
Laurent



Le 06/10/2019 à 10:59, Nicolas Pomarède a écrit :
> Le 06/10/2019 à 10:06, Thorsten Otto a écrit :
> > On Sonntag, 6. Oktober 2019 09:47:08 CEST Thomas Huth wrote:
> > > Opinions?
> >
> > I would do the chaining again as before. Demos are certainly not the 
> > only
> > programs that redirect the gemdos vector, and you'll never know whats 
> > they are
> > trying to achieve. The safest way should be to catch only the calls 
> > that would
> > otherwise go to the ROM, by putting your routine at the end of the 
> > chain.
> >
> > If you don't want to put the code in the cartridge again: another 
> > option would
> > be to insert your illegal opcode directly in the ROM, at the start of 
> > the
> > gemdos dispatcher there. The addresses of all tos versions should be 
> > known,
> > only problem is that they not only depend on the TOS version, but 
> > also on the
> > TOS language.
>
> Hi
>
> I'm not sure it's required to add some illegal opcode or patch the 
> ROM. Maybe another solution could be to add code in the exception() 
> generic handler :
> when an exception occurs, check its number to see if it's the number 
> for trap 1, 13 or 14 for example. Then check if the resulting 
> exception vector is located in rom or not.
> if it's located in rom, call the C code to intercept HD emulation, 
> else don't do know anything special.
>
> of course, one problem happens if a program change trap 1 vector to 
> point to another location in ROM instead of the "official" trap 1 
> vector ; in that case this would call the HD emulation, which would be 
> wrong.
>
> All that put together, maybe the safest way would be build a list of 
> all known tos and for each tos to store in that list the address in 
> rom of the handler for trap 1, 13, 14 or any other handler we could 
> want to patch (line A ?).
> This list could also contain an MD5 of each ROM so that Hatari could 
> confirm a ROM is genuine or not.
> There're several language varations for each version, but in the end 
> maybe it's only 30-40 ROM, which is not that much and the list if 
> finite (this is for atari's tos, emutos can certainly be handled in 
> some ways)
>
> what do you think ?
>
> In the end, I think it would be really important if the HD code could 
> become "stealth" and no game or demo refuse to start when HD emulation 
> is ON (which is the case for several protections)
>
> Nicolas