Mail Archives: djgpp/1995/05/18/12:08:35
Charles Sandmann (sandmann AT praline DOT no DOT neosoft DOT com) writes:
> Joel Hunter wrote:
> > I realize that starting with 2.0, DJGPP-compiled programs will operate
> > only under a DPMI environment, and as such many hardware-interrupt issues
> > will be more easily resolved. However, sometimes your need for speed is so
> > great that you want NO mode-switching when the interrupt occurs. In these
> > cases, you need a real-mode handler for when the interrupt occurs in
> > real-mode. Will we be able to do this in version 2? (Even if it has to be
> > pure assembly I think it would still be very useful.)
>
> Here you are at the mercy of the DPMI provider you are using. If you hook
> both RM and PM interrupts, you should hook the PM interrupt first (since it
> modifieds the RM interrupt to reflect). If the PM interrupt does an IRET
> and does not chain, then you would not need the extra mode switches, if the
> DPMI provider allows this (I think it would work under CWSDPMI).
Can you clarify this? Under GO32 v1.x I believe that it was necessary
to install both a protected-mode handler AND a real-mode handler, to
ensure that interrupts weren't missed when GO32 switched to real-mode
to call DOS/BIOS.
Is it true that a program using GO32 v2 (or any other "real" DPMI
provider) runs totally in protected mode, using V86 mode to access
DOS/BIOS functions, and that a real-mode handler is no longer
absolutely required.
Regards
Nigel
--
_________________________________________________________________________
Nigel Stephens, Algorithmics Ltd, 3 Drayton Park, London, N5 1NU, England
mailto:nigel AT algor DOT co DOT uk http://www.algor.co.uk
phone:+44 171 700 3301 fax:+44 171 700 3400
- Raw text -