From owner-freebsd-hackers Thu Apr 23 08:39:51 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id IAA19435 for freebsd-hackers-outgoing; Thu, 23 Apr 1998 08:39:51 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from sumatra.americantv.com (sumatra.americantv.com [207.170.17.37]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id IAA19400 for ; Thu, 23 Apr 1998 08:39:27 -0700 (PDT) (envelope-from jlemon@americantv.com) Received: from right.PCS (right.PCS [148.105.10.31]) by sumatra.americantv.com (8.8.5/8.8.5) with ESMTP id KAA16797; Thu, 23 Apr 1998 10:39:09 -0500 (CDT) Received: (from jlemon@localhost) by right.PCS (8.6.13/8.6.4) id KAA04582; Thu, 23 Apr 1998 10:38:37 -0500 Message-ID: <19980423103837.32719@right.PCS> Date: Thu, 23 Apr 1998 10:38:37 -0500 From: Jonathan Lemon To: "David E. Cross" Cc: Alfred Perlstein , freebsd-hackers@FreeBSD.ORG Subject: Re: Protected mode instructions which reduce to noop. References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.61.1 In-Reply-To: ; from David E. Cross on Apr 04, 1998 at 11:25:05AM -0400 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Apr 04, 1998 at 11:25:05AM -0400, David E. Cross wrote: > On Thu, 23 Apr 1998, Alfred Perlstein wrote: > > > i'm seriously doubtful of this. i think intels throw instr fault > > exceptions when stuff like that is executed. > > > > -Alfred > > > > On Thu, 23 Apr 1998, David E. Cross wrote: > > > > > Awhile ago it was discussed about implimenting a VM type architecture on > > > intel, and it was agreed that this would be very difficult because intel > > > had decided that instead of throwing an illegal instruction exception for > > > protected mode instructions that were not run as supervisor, it would > > > simply reduce the instriction to NOOP. What are these instructions. > > > > > Heh, I just read my own post... it was not *all* protected mode > instructions, but *some* of them. AFAIK, all privileged instructions, when executed in a non-supervisor context, generate an exception of some sort. This applies to the sti, cli, popfl, I/O family of instructions, as well as those insns which diddle with the control registers. What VM type architecture were you referring to? -- Jonathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message