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From: sef@kithrup.COM (Sean Eric Fagan)
Newsgroups: comp.os.misc
Subject: Re: Call Gates vs. traps
Message-ID: <1991Apr05.083038.21124@kithrup.COM>
Date: 5 Apr 91 08:30:38 GMT
References: <1991Apr3.073617.1167@ibmpcug.co.uk>
Organization: Kithrup Enterprises, Ltd.
Lines: 18

In article <1991Apr3.073617.1167@ibmpcug.co.uk> dylan@ibmpcug.CO.UK (Matthew Farwell) writes:
>Multics and OS/2 use Call Gates to implement system calls, whereas the
>rest of the universe uses traps, yes?  What are the advantages/
>disadvantages of using Call Gates over traps?

Multics and OS/2 use call gates because the hardware is capable of doing
that.  For example, unix for the '386 also uses call gates (call 0x7,0; it's
a simple call gate, true, but it's a call gate nonetheless).

Most processors have a 'syscall' or 'trap' instruction to do that; *nix
tends to use that; *nix for the '386 doesn't use the INT instructions which
are the closest moral equivalent, but the call gates instead.

-- 
Sean Eric Fagan  | "I made the universe, but please don't blame me for it;
sef@kithrup.COM  |  I had a bellyache at the time."
-----------------+           -- The Turtle (Stephen King, _It_)
Any opinions expressed are my own, and generally unpopular with others.