Date:	Sun, 12 Sep 93 18:43:34 -0400
From:	DJ Delorie <dj AT ctron DOT com>
To:	pynq AT midway DOT uchicago DOT edu
Cc:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Re: DJGPP & OS/2 - fact or myth?

> 	Since DJGPP can now use DPMI memory, it can now, theoretically,
> 	be used in a DOS box under OS/2.  However, since the DPMI usage
> 	requires a minimum of 5M of memory on startup and since,
> 	IMHO&LE, one rarely has that much free (physical) memory available
> 	on an OS/2 machine, the net result is that you cannot use DJGPP
> 	under OS/2.

> Regarding the memory, it seems that somehow, the OS manages to suck
> most of it up for one reason or another.  One of my home machines has
> 16M of memory and only a few small windows open, yet when I run a DJGPP
> compiled app in a DOS box, it still barfs out, viz:

The problem with DPMI memory is that the linker is still producing
a.out binaries, in which data starts at the 4M boundary.  Since DPMI
0.9 can't do linear page mapping, go32 must allocate at least 4M of
*available* memory (that's a big segment) to run the program in.

As of 1.11, the default linker produces COFF binaries, which take up
much less memory.

Note that the problem isn't OS/2 related, it's related to whether or
not your DPMI server virtualizes memory enough to not require physical
memory for the gap between end of code and start of data.

DJ

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