From: "Charles Sandmann" <sandmann AT clio DOT rice DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: DPMI and CALDERA-DOS
Date: Sun,  4 Jul 1999 16:12:01
Organization: Aspen Technology, Inc.
Lines: 56
Message-ID: <377f87d1.sandmann@clio.rice.edu>
References: <7lfr7s$dpm$1 AT nnrp1 DOT deja DOT com>
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

> Here the effects:
> 1) I'm running DOS with Caldera-Emm386 as DPMI-
>    server.
>    1.1. no TaskManager:
>      - everything is fine. I get errormessges
>        when compiling programs with systax errors
>    1.2. TaskManager enabled, running 1 Task:
>      - I get no errormessges when compiling
>        programs with systax errors

This sounds like a problem with STDERR being messed up?
Do writes to STDERR work? From nested programs?  I suspect
a bug which nested DPMI programs close STDERR so future
nested programs can't write to it?

>    1.3. TaskManager enabled, running 2 Tasks
>         with programms needing DPMI (Hello world)
>      - normally it works, sometimes the system
>        crashes or hangs.

Try rebuilding the libc routines which hook hardware interrupts
for CTRL-C handling and floating point errors and disable this
feature and try multiple images and see if that helps.  That's the
only feature which should potentially have cross virtual machine
effects.  If it still crashes after disabling the hardware 
interrupt hooking, it's just a TaskManager/Caldera EMM bug.

> 2) I'm running DOS with cwsdpmi instead of DR-DOS-EMM386
>    with DPMI enabled.
>    1.2. TaskManager enabled, running 1 Task:
>      - everything is fine. I get errormessges
>        when compiling programs with systax errors
>    1.3. TaskManager enabled, running 2 Tasks
>         with programms needing DPMI (Hello world)
>      - I get the error mesage:
>        "Warning: cannot open swap file C:\cwsdpmi.swp"
>      - or the system crashes.

The warning is just a warning - that both processes can't use
virtual memory.  You could run one process specifying -s on the
command line with CWSDPMI as a TSR to specify a different swap
file - but that would just get rid of the warning message.

It shouldn't crash.  Early CWSDPMI versions were tested with Quarterdeck's
Deskview and it worked fine there.  It should appear as just two VCPI
clients running at the same time.  I would also recommend removing the
hardware interrupt handling code in each image (see above) and see if
that helps.  It may be a multiple machine interrupt virtualization 
issue.

> So my problems are:
> - I can't compile when the Taskmanager ist enabled (when
>   using EMM386 of DR-DOS as dpmi-server)
> - I can't run two programms build with djgpp without crash.

Try the above and see if anything helps