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From: jss@sjuvax.UUCP (J. Shapiro)
Newsgroups: net.micro.16k
Subject: Query about interrupt/trap handling
Message-ID: <1179@sjuvax.UUCP>
Date: Sat, 22-Jun-85 22:40:19 EDT
Article-I.D.: sjuvax.1179
Posted: Sat Jun 22 22:40:19 1985
Date-Received: Mon, 24-Jun-85 06:19:51 EDT
Distribution: net
Organization: Haverford College, Haverford, Pa.
Lines: 20

This may have come up before, and I suspect that I already know the answer,
but maybe someone out there who has seen it in their hands can tell me for
sure.

In the manuals, I see no indication as to whether traps/interrupts are
processed in user mode or supervisor mode. This is important, as if such
things are handled in supervisor mode and one is clever about using traps
(which one has to be for some security), then one can remove all of the
worries about interrupt routines from the user address space in a  system
using an MMU by placing these routines in the system space and using the
A24 bit that the MMU gives as one of the decoding lines for handling
things.

What's the verdict? My guess is that these things are handled in supervisor
mode. If I missed the reference, would someone be kind enough to point it out to me?

Thank you,


Jonathan S. Shapiro