From owner-freebsd-hackers Wed Nov 12 08:45:38 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id IAA16557 for hackers-outgoing; Wed, 12 Nov 1997 08:45:38 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from horst.bfd.com (horst.bfd.com [204.160.242.10]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id IAA16549 for ; Wed, 12 Nov 1997 08:45:29 -0800 (PST) (envelope-from ejs@bfd.com) Received: from harlie.bfd.com (bastion.bfd.com [204.160.242.14]) by horst.bfd.com (8.8.5/8.7.3) with SMTP id IAA05474; Wed, 12 Nov 1997 08:45:20 -0800 (PST) Date: Wed, 12 Nov 1997 08:45:20 -0800 (PST) From: "Eric J. Schwertfeger" To: gad@eclipse.its.rpi.edu cc: hackers@FreeBSD.ORG Subject: Re: Virtual Intel Machines? In-Reply-To: <9711120909.AA16549@mlor.its.rpi.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Wed, 12 Nov 1997, Garance A Drosehn wrote: > In the land of IBM mainframes, there's an operating system (of > sorts) called VM. This is an operating system which lets you run > multiple operating systems on a single machine, at the same time. > VM can allocate devices between the running systems, so that one > running OS sees a given hard disk (for example), but no other > operating systems can possibly get to that hard disk. > > What I was wondering is if something similar could be done with > Intel-ish chips? I realize this wouldn't be a trivial thing to > write, but it'd be mighty convenient to have in some circumstances > (at least in an academic setting). Not in the strictest sense, because Intel, in their infinite wisdom, decided that certain privledged instructions, if executed in an unprivledged state, would not trap, but rather reduce to a NOP. Hence, the VM equiv can't trap the OS's attempt to do this, and make it happen, given appropriate permissions.