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List:       linux-msdos
Subject:    Re: Hoo boy!  This is going to be interesting.
From:       Steve Cohen <stevecoh1 () comcast ! net>
Date:       2010-10-18 17:44:10
Message-ID: 4CBC876A.90204 () comcast ! net
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On 10/08/2010 03:22 PM, Frank Cox wrote:
> 
> On Fri, 2010-10-08 at 14:25 -0500, Steve Cohen wrote:
> > Can someone tell me what this error message indicates and
> > where I might possibly go to figure out how to fix it?
> 
> What version of dosemu are you trying to use?
> 
> Is the problem with dosemu or with freedos?  Have you tried running your
> application under "native" freedos?  Have you tried running your
> application under dosemu with ms-dos (or whatever dos version you run it
> under now)?
> 
> What language is your application written in?  Do you have the source
> code and a suitable compiler?  If so, are you sufficiently familiar with
> the programming that you can play with the source code for your
> application and find out exactly what's causing it to blow up?
> 
> What kind of application are you using?  Process control?  Database?
> Custom hardware driver?  Something else?
> 

Sorry for the lapse.  I was on vacation.  Thanks for your help.

It's 1.4, the version you get with apt-get from Ubuntu 10.04 and the 
latest stable version, I believe.

This error happens under freedos.  I have not yet tried running it under 
MS-DOS, which is what it runs under normally.

The application is a legacy app written about 20 years ago in C.  We 
have source code for all the code that was written by our organization 
and for some of the third party libraries that were used.  These include 
CScape (for which we do have source) and the Greenleaf Communications 
Library, for which, thus far, we don't.  The application also uses some 
version of the PharLap DOS Extender, which currently is at the top of my 
suspect list for this problem.  I've read the EMUfailure page, which 
mentions that

> Older versions of the Pharlap Extender (run286) need ring-0 access under DOSEMU to \
> install their own DPMI server. The use of proprietary undocumented extensions to \
> the DPMI protocol makes DOSEMU's DPMI server unsuitable for this extender.

I don't see run286 as something we're loading and the version of PharLap 
we are using includes the binaries phar2_ir.dll and phar2_ir.lib.  Can 
someone confirm that this IS or ISN'T the version of PharLap that won't 
work with DOSemu?  It appears to be the Greenleaf library that needs the 
PharLap and they include a header called phar286.h to support it.

The application is an operator console for a telephony-based system.  It 
uses the serial port to communicate with a phone-dialing device.  It 
also has a network interface to the back-end part of this system which 
handles switching, billing, and other interfaces.

Although we have source code and suitable compilers, tweaking it much is 
probably not an option for business reasons.  We are on a 2-week 
fish-or-cut-bait time frame for evaluating DOSEMU for this purpose.  If 
we can't get this to work, we will look at rewriting instead, which is 
our preferred long-term solution.  DOSEMU, if it proves out in the two 
weeks allotted, would be the short term solution.  The reason for this 
whole effort is hardware exhaustion - we haven't figured out a workable 
way to replace the old hardware, and are running out of suitable 
replacements, which are no longer available.

Steve Cohen
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