From owner-freebsd-arch  Sat Jan 26  0:52:12 2002
Delivered-To: freebsd-arch@freebsd.org
Received: from albatross.prod.itd.earthlink.net (albatross.mail.pas.earthlink.net [207.217.120.120])
	by hub.freebsd.org (Postfix) with ESMTP id 4C7C437B404
	for <arch@freebsd.org>; Sat, 26 Jan 2002 00:52:09 -0800 (PST)
Received: from pool0040.cvx40-bradley.dialup.earthlink.net ([216.244.42.40] helo=mindspring.com)
	by albatross.prod.itd.earthlink.net with esmtp (Exim 3.33 #1)
	id 16UOZ0-0006QM-00; Sat, 26 Jan 2002 00:51:54 -0800
Message-ID: <3C526E25.3B72F578@mindspring.com>
Date: Sat, 26 Jan 2002 00:51:49 -0800
From: Terry Lambert <tlambert2@mindspring.com>
X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony}  (Win98; U)
X-Accept-Language: en
MIME-Version: 1.0
To: Nate Williams <nate@yogotech.com>
Cc: Daniel Eischen <eischen@pcnet1.pcnet.com>,
	Dan Eischen <eischen@vigrid.com>, k Macy <kip_macy@yahoo.com>,
	Peter Wemm <peter@wemm.org>, Julian Elischer <julian@vicor-nb.com>,
	arch@FreeBSD.ORG
Subject: Re: KSE question
References: <3C51D0B6.F6E04EBC@mindspring.com>
		<Pine.SUN.3.91.1020125164325.24428A-100000@pcnet1.pcnet.com>
		<15441.56832.170618.611705@caddis.yogotech.com>
		<3C51E888.FD13A18D@mindspring.com>
		<15441.59691.361172.394760@caddis.yogotech.com>
		<3C51F18A.C0D8D6B1@mindspring.com>
		<15441.62092.864056.841853@caddis.yogotech.com>
		<3C51F492.CB0FB69E@mindspring.com>
		<15441.62830.180895.121111@caddis.yogotech.com>
		<3C51F89E.78DAD01D@mindspring.com>
		<15441.63876.271856.290838@caddis.yogotech.com>
		<3C51FF0A.9ACAC316@mindspring.com> <15442.16478.408033.680185@caddis.yogotech.com>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-arch.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-arch>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-arch>
X-Loop: FreeBSD.ORG

Nate Williams wrote:
> Again, the issue is that we can't determine *IF* the FPU has been used
> effeciently.  All solutions assume this solution, although Daniel's may
> have a way of short-circuiting this in the short term.

Disable it in the processor when context switching in code
that doesn't have it marked enabled (this can be lazy bound
as well: the default state will be disabled.

When the first access by a program occurs, it will get an
instruction fault.

Handle the fault by setting an "FPU used" flag, and then
enabling it and restarting the instruction.

-- Terry

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message