Xref:	news-dnh.mv.net comp.os.msdos.djgpp:3229
Path:	news-dnh.mv.net!mv!news.sprintlink.net!newsfeed.internetmci.com!news.sesqui.net!rice!news!sandmann
From:	Charles Sandmann <sandmann AT clio DOT rice DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: __djgpp_ds_alias - Why?
Date:	Tue, 14 Nov 1995 09:11:52 CST
Organization:	Rice University, Houston, Texas
Lines:	17
References:	<488hkt$cri AT solnews DOT solsource DOT net>
Reply-To:	sandmann AT clio DOT rice DOT edu
Nntp-Posting-Host:	clio.rice.edu
To:	djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway:	from newsgroup comp.os.msdos.djgpp

> 1.  What is its purpose?

The hardware interrupt to exception algorithm in V2 twiddles with the 
limits on DS to re-schedule hardware interrupt signals to a time when
they can be handled in an appropriate manner.  But some uses of DS must
not trigger exceptions, especially inside a DPMI host.  Very complicated,
send me email if you want ugly details.

> 2.  Why is it different from ds?

It should be identical in all cases except when we want to cause the 
executing program to raise a signal.

> 3.  Why does it seem to be required in the handlers for some interrupts
> (timer) but not others (keyboard)?

If you see a seeming inconsistency, send me a note, it may be an oversight.

- Raw text -