From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Newsgroups: comp.os.msdos.programmer,comp.os.msdos.djgpp
Subject: Re: WARNING: DOS is about to die.
Date: Tue, 14 Sep 1999 10:57:40 +0200
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On 13 Sep 1999, Steve Mentzer wrote:

> >For example, did you know you cannot catch SIGINT and SIGFPE on NT?  If 
> >you do, your program crashes, and the DrWatson log file clearly shows 
> >that it's an NT bug.
> 
> And you shouldn't be able to... The only thing that should be handling 
> interrupts are kernel-mode device drivers, not user mode applications.

If that would be the reason, then I'd at least understand it.

But the reality doesn't fit into the above theory: NT *does* let you 
catch hardware interrupts.  What causes the crashes is that NT apparently 
uses the application's stack to perform some of its chores when an 
application triggers an exception (such as GPF), e.g. by accessing an 
invalid address.  And that's a no-no, since one of the reasons for a GPF 
is that the data/stack segment is invalid.

DJGPP supports signals by converting an interrupt into an exception, by 
invalidating the DS selector.  And this is why the program crashes on NT.