Re: [MiNT] update:WRITE_BOOT,ALLOW_TRP_CHG

["Helmut Karlowski" <helmut.karlowski@ish.de>]

Peter Persson, 04.10.2012 12:35:48:

> 2012/10/4 Helmut Karlowski <helmut.karlowski@ish.de>:
> > It is Setexc, not Ssystem (been too long when I implemented this).  
> > Ssystem
> > is used to change the behaviour of Setexc.
>
> Hmm... could you elaborate this a bit? Ssystem() offers stuff like
> S_SETLVAL/S_GETLVAL to read the supervisor protected area, and so does

Right - did not know about these. But it only allows to change addresses  
between 0x420 and 0xfffc. I guess the traps are below 0x420, so either  
this needs another treatment or could be handled by ALLOW_TRP_CHG? Not  
sure.

> So how does Ssystem() change the behavior of Setexc()? Is this something  
> new?

Ssystem(S_ALLOW_TRP_CHG, arg, 0);

will change the behaviour of Setexc (allow or not, depending on arg).

> > There will be another patch for XaAES where it can be activated by  
> > XaAES so
> > any dirty prgs run before XaAES won't be affected.
>
> Probably a good idea, since "dirty" is often "the cleanest possible
> way to do it" on this platform, since we lack APIs & proper mechanisms

I cannot imagine a situation where it is possible to change the traps in  
serious usage.

> for... well... most stuff. Still I think it's a good idea to make it
> possible to restrict these things, as long as it is optional for the
> user.

Stabilize it!

--
Helmut Karlowski