From owner-svn-src-head@FreeBSD.ORG Wed Nov 4 18:17:23 2009 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 999C11065672; Wed, 4 Nov 2009 18:17:23 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id 644E28FC15; Wed, 4 Nov 2009 18:17:23 +0000 (UTC) Received: from bigwig.baldwin.cx (66.111.2.69.static.nyinternet.net [66.111.2.69]) by cyrus.watson.org (Postfix) with ESMTPSA id E0C1746B1A; Wed, 4 Nov 2009 13:17:22 -0500 (EST) Received: from jhbbsd.hudson-trading.com (unknown [209.249.190.8]) by bigwig.baldwin.cx (Postfix) with ESMTPA id 0CAD18A01B; Wed, 4 Nov 2009 13:17:19 -0500 (EST) From: John Baldwin To: Attilio Rao Date: Wed, 4 Nov 2009 13:12:36 -0500 User-Agent: KMail/1.9.7 References: <200911040132.nA41WxtQ012750@svn.freebsd.org> <86y6mmff1a.fsf@ds4.des.no> <3bbf2fe10911040815u780ea5d5h8252b46ddf0c5de7@mail.gmail.com> In-Reply-To: <3bbf2fe10911040815u780ea5d5h8252b46ddf0c5de7@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Message-Id: <200911041312.37676.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.0.1 (bigwig.baldwin.cx); Wed, 04 Nov 2009 13:17:19 -0500 (EST) X-Virus-Scanned: clamav-milter 0.95.1 at bigwig.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-2.5 required=4.2 tests=AWL,BAYES_00,RDNS_NONE autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on bigwig.baldwin.cx Cc: svn-src-head@freebsd.org, Dag-Erling =?utf-8?q?Sm=C3=B8rgrav?= , svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r198868 - in head/sys: amd64/amd64 i386/i386 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Nov 2009 18:17:23 -0000 On Wednesday 04 November 2009 11:15:28 am Attilio Rao wrote: > 2009/11/4, Dag-Erling Sm=C3=B8rgrav : > > Attilio Rao writes: > > > Dag-Erling Sm=C3=B8rgrav writes: > > > > According to the reference you gave, OpenSolaris has a workaround f= or > > > > this issue. Perhaps we should adopt it? > > > IIRC, based on what I readed on-line, it could be still a WARNING msg, > > > but I didn't double-check for it. > > > > Uh, apparently, it can be worked around with an additional lfence > > instruction... See the first couple of comments on that bugzilla page > > you linked to. If the cost is too high, we could make it conditional on > > "options BROKEN_OPTERON_E" or something. >=20 > Yeah but the lfence is completely impratical from the overhead POV -- > and actually I don't like the idea to add a compile time option based > on family/model. > We could maybe do a mixed approach: printout the WARNING msg only if > the BROKEN_OPTERON_E is not used otherwise be ok. > I still don't like it because it is going to dirty the atomic.h code a > bit, but it can be an acceptable compromise. We have had family/model specific hacks with an associated #ifdef in the pa= st,=20 see NO_F00F_HACK (though that is probably less invasive). Also, if it=20 affects atomic.h then you may need to leave it always enabled in userland t= o=20 be truly safe. =2D-=20 John Baldwin