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From: amos@instable.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: copyin
Message-ID: <713@instable.UUCP>
Date: Wed, 11-Mar-87 09:12:33 EST
Article-I.D.: instable.713
Posted: Wed Mar 11 09:12:33 1987
Date-Received: Fri, 13-Mar-87 00:13:12 EST
References: <4838@brl-adm.ARPA>
Reply-To: amos%nsta@nsc.com (Amos Shapir)
Distribution: world
Organization: National Semiconductor (Israel) Ltd.
Lines: 12

When in kernel mode on a VAX, you have both kernel and user spaces mapped,
since they do not overlap virtually. Copyin/copyout do not use special
instructions, but they do sanity checks without which a mistake by a user
might crash the system.

(A side effect of this is that the u struct is accessible from user mode,
although read-only).
-- 
	Amos Shapir
National Semiconductor (Israel)
6 Maskit st. P.O.B. 3007, Herzlia 46104, Israel
(011-972) 52-522261  amos%nsta@nsc.com 34.48'E 32.10'N