From owner-svn-src-all@FreeBSD.ORG  Wed Mar 16 20:34:23 2011
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@FreeBSD.org
Received: from [127.0.0.1] (freefall.freebsd.org [IPv6:2001:4f8:fff6::28])
	by hub.freebsd.org (Postfix) with ESMTP id 73134106566B;
	Wed, 16 Mar 2011 20:34:20 +0000 (UTC)
	(envelope-from jkim@FreeBSD.org)
From: Jung-uk Kim <jkim@FreeBSD.org>
To: Roman Divacky <rdivacky@FreeBSD.org>,
 Bruce Evans <brde@optusnet.com.au>
Date: Wed, 16 Mar 2011 16:34:04 -0400
User-Agent: KMail/1.6.2
References: <201103152145.p2FLjAlt060256@svn.freebsd.org>
	<201103161233.16347.jkim@FreeBSD.org>
	<20110316174553.GA6367@freebsd.org>
In-Reply-To: <20110316174553.GA6367@freebsd.org>
MIME-Version: 1.0
Content-Disposition: inline
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Message-Id: <201103161634.08104.jkim@FreeBSD.org>
Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org, Maxim Dounin <mdounin@mdounin.ru>
Subject: Re: svn commit: r219679 - head/sys/i386/include
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 16 Mar 2011 20:34:23 -0000

On Wednesday 16 March 2011 01:45 pm, Roman Divacky wrote:
> On Wed, Mar 16, 2011 at 12:32:56PM -0400, Jung-uk Kim wrote:
> > On Tuesday 15 March 2011 08:45 pm, Maxim Dounin wrote:
> > > This isn't really different as long as GENERIC kernel used, as
> > > GENERIC defines I486_CPU.
> >
> > Fixed in r219698, sorry.
> >
> > Actually, I think we should remove i486 from GENERIC at some
> > point. It has too many limitations.  For example, I really love
> > to implement atomic 64-bit mem read/write using cmpxchg8b (no
> > 0xf00f joke, please) but I cannot do that cleanly without
> > removing I486 support or checking cpu_class at run-time. :-(
>
> if we drop i486 I think it makes sense to require something that
> has at least SSE2, thus we can have the same expectations as on
> amd64.
>
> and we can use sse2 unconditionally (str*, mem* etc.)

This is a proof-of-concept patch for sys/x86/isa/clock.c:

http://people.freebsd.org/~jkim/clock.diff

You see the complexity, just because I wanted to load 64-bit value 
atomically... :-(

Jung-uk Kim