From: Sengan DOT Short AT durham DOT ac DOT uk
Message-Id: <22000.9608031330@ws-ai5.dur.ac.uk>
Subject: Your int question
To: snarfy AT goodnet DOT com
Date: Sat, 3 Aug 1996 14:30:26 +0100 (BST)
Cc: djgpp AT delorie DOT com
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Hi Josh,

Not too much is needed: save all registers you use, make sure you do the sti
before the iret. If you want to use code/dataspace from your code,
you must set up the selectors right:  Set ds = [__djgpp_ds_alias].
You ought to check if you are already in the handler, if your code is
non-rentrant and uses the stack (DPMI stack for interrupts has a limited size).

DPMI switches stack for you, and the int saves EFLAGS. 

The code to read is in djpsrc200/src/libc/go32/gopint.c
It's also in my variant of lwp on my web page in sengan/gopint.

Sengan