From: Daniel Schroeder <Daniel DOT Schroeder AT rsd DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: Need help - CWSDPMI "can't allocate page table mem" error
Date: Wed, 08 Oct 1997 11:44:17 +0200
Organization: Interserv News Service
Lines: 54
Message-ID: <343B55F1.26C09B75@rsd.de>
NNTP-Posting-Host: 206.175.1.194
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

Hi!

I am writing a program for a PC-based system that needs to handle very
large amounts of dynamically allocated memory (definitely more than the
available physical memory). So I tried the following combination:

- Watcom 11.0 compiler with target system set to Pmode/W on the
development machine
- Pmode/W 1.33
- CWSDPMI V0.90+ (r3)
- Caldera OpenDOS 7.01 on the target system, with *no* HIMEM.SYS or
EMM386 or any other memory manager loaded apart from CWSDPMI. Also,
there are no other TSRs or drivers loaded.

The CWSDPMI is obviously only needed for the virtual memory support. But
I definitely need that virtual memory - physical memory is just too
expensive if you have to multiply it by 2000 (that's the number of
systems we are going to build).

Now, whenever I try to run a 32-bit test program as simple as "Hello
world!" on the target machine, CWSDPMI gives me the error message
"Error: could not allocate page table memory" when starting the program.
The same program works correctly if CWSDPMI is *not* loaded (but of
course then there's no virtual memory).

The docs mention that error message, so I tried the suggestions there: I
set the "number of page tables to initially allocate" to 20 (is that a
reasonable value?), so to avoid dynamic allocation, but this didn't
help. Next I tried to increase free conventional memory - using
PMWSETUP, I set "Low Memory to Reserve (in Paragraphs)" to 0x2000
paragraphs (again, a reasonable value?), but that didn't help either.
DOS/4GW seems to work here, but for several reasons I'd rather use
Pmode/W instead.

Now I'm sort of stuck... can anybody help me by answering some of these
questions?

- First of all: does the combination of programs I chose make sense at
all, or are there other, better solutions?

- What exactly is going on to make that error appear? Is it really
conventional memory that is lacking, or is CWSDPMI running out of some
other resource?

- Are there any other configuration options I need to change to make it
work?

Any help appreciated!

---

  Daniel Schroeder
  Rohde & Schwarz Germany
  email: Daniel DOT Schroeder AT rsd DOT de