From owner-freebsd-hackers Thu Nov 19 16:53:19 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id QAA18614 for freebsd-hackers-outgoing; Thu, 19 Nov 1998 16:53:19 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from smtp03.primenet.com (smtp03.primenet.com [206.165.6.133]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id QAA18604 for ; Thu, 19 Nov 1998 16:53:17 -0800 (PST) (envelope-from tlambert@usr09.primenet.com) Received: (from daemon@localhost) by smtp03.primenet.com (8.8.8/8.8.8) id RAA22087; Thu, 19 Nov 1998 17:52:43 -0700 (MST) Received: from usr09.primenet.com(206.165.6.209) via SMTP by smtp03.primenet.com, id smtpd022025; Thu Nov 19 17:52:38 1998 Received: (from tlambert@localhost) by usr09.primenet.com (8.8.5/8.8.5) id RAA21672; Thu, 19 Nov 1998 17:52:37 -0700 (MST) From: Terry Lambert Message-Id: <199811200052.RAA21672@usr09.primenet.com> Subject: Re: FreeBSD on i386 memory model To: dillon@apollo.backplane.com (Matthew Dillon) Date: Fri, 20 Nov 1998 00:52:36 +0000 (GMT) Cc: Marius.Bendiksen@scancall.no, tlambert@primenet.com, rnordier@nordier.com, freebsd-hackers@FreeBSD.ORG In-Reply-To: <199811181842.KAA06180@apollo.backplane.com> from "Matthew Dillon" at Nov 18, 98 10:42:50 am X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > On the 386 and 486, call gates are faster. On the pentium, pentium-PRO, > and pentium-II, interrupts are faster. > > Argument copying is wasteful and has limited use on systems where the > supervisor has access to the user mode memory map. FreeBSD (and virtually > all other operating systems) uses a two-layer design, not a multi-layer > ring design. About the only thing you might see different between OS's > is that some processors have a separate 'interrupt stack'. On Intel cpu's, > however, the abstraction is useless due to the completely broken ring > design because many supervisor instructions only work in ring 0. ring 1 > and ring 2 are almost completely useless. It is useful for the utilization of Windows VxD's in whatever kernel that whatever kernel support putting the Windows VxD's in a seperate VM space. This is also useful for NetWare NLM's. Not that anyone would want to leverage billions of dollars of commercial developement to save a few decades of driver writing... Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message