Date: Tue, 23 Jan 1996 08:06:33 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: taupin AT lps DOT u-psud DOT fr
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: djgpp in windows 3.11 DOS window


On Mon, 22 Jan 1996 taupin AT lps DOT u-psud DOT fr wrote:

>  2.a Did somebody experience crashes when running any djgpp program (with
> GO32 included) inside the DOS window of Windows ?
> 
>  2.b I suspect this was due to a memory overlapping between windows memory
> management and GO32 memory requests. Am I right ? Subsidiary question:
> has windows 3.11 a memory protection preventing the DOS window writing
> outside its std allocated area ?

Win3.1 does run in protected mode, but its protection is only up to a 
point.  I've seen cases when commercial programs has crashed and brought 
down the entire system with them.  DOS boxes are protected less than 
native Windows programs (as far as I know) because they don't run in 
their private address space.

For DJGPP programs, the first place to look is where you call software
interrupts directly (through `int86', `intdos', `_go32_dpmi_simulate_int'
and the like.  You can thrash your disk easily with a wrong value in a 
wrong register.  I don't think the ``memory overlapping'' is an issue, 
because GO32 relies on Windows for memory management when you run your 
programs in DOS box.  Only outside Windows does GO32 manage the memory 
itself (and even then it uses services of memory managers like EMM or 
QEMM if present).