Date: Tue, 5 Oct 93 16:57:56 -0400
From: DJ Delorie <dj AT ctron DOT com>
To: rri!potter AT vtserf DOT cc DOT vt DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: _harderr replacement

In 1.11, you could trap the critical error handlers with a DPMI
real-mode callback.  The trick is that you can't do much other than
set a flag from the handler because of the way DPMI handles the stack.

Note that this is more lenient in non-DPMI environments, but it's
still dangerous to do system calls from an interrupt handler.  You
might be able to get away with BIOS calls, but I don't know if I can
guarantee it just yet.

In no case can you longjmp out of an interrupt handler.