From owner-svn-src-head@FreeBSD.ORG Wed Nov 4 16:06:38 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 BBB2910656A9; Wed, 4 Nov 2009 16:06:38 +0000 (UTC) (envelope-from asmrookie@gmail.com) Received: from mail-bw0-f213.google.com (mail-bw0-f213.google.com [209.85.218.213]) by mx1.freebsd.org (Postfix) with ESMTP id D849B8FC30; Wed, 4 Nov 2009 16:06:37 +0000 (UTC) Received: by bwz5 with SMTP id 5so9260169bwz.3 for ; Wed, 04 Nov 2009 08:06:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type; bh=zj1iyIXz2AWPAdorvE2ogt1ZSYMhLEALHRSHYmCUmko=; b=qWtIYdYRkQCzXEK6co4d9kFMnN678KnisWRUHOMoaRy0zlFCPb4IH4U8vZOr+ROSiu hP/uKUEWTM9yXVDCLi7eTncJoIwrd5PuYzR9rid254efmClrtyWuEsmwjeELMS7JN6JW E82Bc8ysFeOHp+x1MnpUIqllipR3pCLBdBnFI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=bN+i5alEOREHhhvpvUyEPvOo7hjRAtUz11Y3Qss+MWeul/WTsGK8x/ISUlFSP98F6D Kcoeum2CPbGVBlFPx8s2/ghugHYxu+cfEF4zazsP0XDZzAcvo3p/o0kS6IqM+SH1Atey FsVfESM1ZIUp2+8bePL+Ghg2FewxhQdp9tjtI= MIME-Version: 1.0 Sender: asmrookie@gmail.com Received: by 10.223.161.215 with SMTP id s23mr234223fax.44.1257350796479; Wed, 04 Nov 2009 08:06:36 -0800 (PST) In-Reply-To: <20091104144315.GH2331@deviant.kiev.zoral.com.ua> References: <200911040132.nA41WxtQ012750@svn.freebsd.org> <20091104055811.GY1293@hoeg.nl> <3bbf2fe10911040449j5938ca7eqca5829ceced66f48@mail.gmail.com> <20091104144315.GH2331@deviant.kiev.zoral.com.ua> Date: Wed, 4 Nov 2009 17:06:36 +0100 X-Google-Sender-Auth: 36394d47c77d16f5 Message-ID: <3bbf2fe10911040806r37f00a8dq2aa3ccd1e5c7b241@mail.gmail.com> From: Attilio Rao To: Kostik Belousov Content-Type: text/plain; charset=UTF-8 Cc: svn-src-head@freebsd.org, Ed Schouten , 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 16:06:38 -0000 2009/11/4, Kostik Belousov : > On Wed, Nov 04, 2009 at 01:49:41PM +0100, Attilio Rao wrote: > > 2009/11/4 Ed Schouten : > > > Hi Attilio, > > > > > > * Attilio Rao wrote: > > >> Opteron rev E family of processor expose a bug where, in very rare > > >> ocassions, memory barriers semantic is not honoured by the hardware > > >> itself. As a result, some random breakage can happen in uninvestigable > > >> ways (for further explanation see at the content of the commit itself). > > > > > > Ooh. Sounds like an interesting bug. > > > > > > The bug doesn't manifest itself on UP, right? If so, maybe we should add > > > some very short instructions to the warning on how to disable SMP. > > > > Due to the semantic of the bug, I think that it can manifest itself on > > UP and a memory barrier failing on UP means that PREEMPTION can blow > > up. Considering this I wouldn't suggest anything different between the > > UP vs SMP case. > > CPU is always self-consistent, isn't it ? > > Also, I very much dislike idea of making our kernel a collection of > references to the man pages and URLs, esp. when URL point to the > resource not controlled by the project. Ok, as long as you are in favor of stripping the URL, I'm fine with it. Attilio -- Peace can only be achieved by understanding - A. Einstein