From:	"Damian Yerrick" <web DOT poison AT pineight DOT 8m DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: DPMI Crash Program
Date:	Mon, 27 Sep 1999 23:15:51 -0500
Organization:	Rose-Hulman Institute of Technology
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References:	<7spe65$du7$1 AT nnrp1 DOT deja DOT com>
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<hank_heng AT hotmail DOT com> wrote in message news:7spe65$du7$1 AT nnrp1 DOT deja DOT com...
> Hi,
>
>   I compile my source with DJGPP, then when I try to run it under true
> DOS mode, even with the CWSDPMI installed, it will not run the program
> but saying something like :
>
>      Exiting due to signal SIGSEGV
>      Page fault ........

A page fault means that either the virtual memory screwed up
(you need to ScanDisk your hard drive), or you accessed the
Forbidden First Four Kilobytes.

Windows 9x's DPMI manager does not trap accesses to the
first 4K, but CWSDPMI does. Your program is most likely
dereferencing a NULL pointer.

>      (some more lines of numbers)

Run symify on your program. It should add function names to
those numbers, to help you trace where the bug is coming from.
If you still don't understand, post what is asked for on the
MFAQ List:
http://www.rose-hulman.edu/~yerricde/mini-faq.txt

>   But the problem doesn't exist when I run the program in Windows95's
> DOS box, so I think it might cause by the DPMI manager, I try it on
> diffrent PC with diffrent configuration, but my program still does'n
> run under TRUE DOS MODE.
>
>   So... How do I fix the problem so that my program will work in TRUE
> DOS MODE and Windows95's DOS box ? Do I need to use some other DPMI
> manager other then CWSDPMI ?

Are you even using CWSDPMI? QEMM's QDPMI is notorious
for bugginess.

>   Oh, one more thing, how do you link DPMI into my program in order it
> to run without need to shiping the DPMI manager every time I pass up my
> assignment ?

Copy CWSDPMI.exe onto the user's PATH. And, if you UPX
it, CWSDPMI.exe is only 20 kilobytes.

Damian Yerrick
http://come.to/yerrick

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