From: "Charles Sandmann" <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Announce: CWSDPMI r5 public beta
Date: Sat, 21 Oct 2000 16:18:14
Organization: Aspen Technology, Inc.
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> How about a default that would leave enough DOS memory for some
> reasonable number of nested DJGPP programs (2? 3?), in addition to a
> CWSPARAM parameter that controls how much DOS memory can be used?

The current default "leave it alone" dos memory is around 64Kb, which should
be enough for 4 more nestings.  But the current page table request was
bypassing that.  I was then thinking about how many people need to use
more than 128Mb, versus how many people might want that memory for everything
from nesting programs to DMA buffers.  Somewhat arbitrarily I decided that
an initial allocation of 128Mb worth of pagetables (if you have more than
128Mb of memory) should be enough.  On a typical machine, this is still
going to leave probably 300Kb+ of DOS memory free.  And CWSDPMI will still
try to allocate that memory on demand if you touch more than 128Mb of 
memory.  (The later allocation should be avoided since it fragments DOS
memory and causes some alignment memory waste).  This is the "auto" choice,
and you still have the ability to override this with CWSPARAM if you don't
like it.

I could try to do something more complicated, but at this point I'm afraid
of breaking something this soon before a release.  Since there was a bug
in using physical memory more than 128Mb in r4, I'm pretty sure 128Mb is
an upper limit default which won't cause too many problems.  Since 256Mb
was the most you could see in r4, and I didn't hear about the out of
memory problem (256K of DOS memory in pagetables) - it seems that cutting 
that to 128K is a benefit even for those machines.

I'm going to do some internal testing on this and several other "minor"
changes and decide if I just release it or do a second beta.