From owner-freebsd-alpha@FreeBSD.ORG Thu Feb 7 22:06:26 2008 Return-Path: Delivered-To: freebsd-alpha@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 64EBB16A418 for ; Thu, 7 Feb 2008 22:06:26 +0000 (UTC) (envelope-from ticso@cicely12.cicely.de) Received: from raven.bwct.de (raven.bwct.de [85.159.14.73]) by mx1.freebsd.org (Postfix) with ESMTP id D165F13C447 for ; Thu, 7 Feb 2008 22:06:25 +0000 (UTC) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de ([10.1.1.7]) by raven.bwct.de (8.13.4/8.13.4) with ESMTP id m17M6N2d017198; Thu, 7 Feb 2008 23:06:23 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [10.1.1.14]) by cicely5.cicely.de (8.13.4/8.13.4) with ESMTP id m17M6Hjh005480 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 7 Feb 2008 23:06:18 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.13.4/8.13.3) with ESMTP id m17M6Hnt033193; Thu, 7 Feb 2008 23:06:17 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.13.4/8.13.3/Submit) id m17M6Hg9033192; Thu, 7 Feb 2008 23:06:17 +0100 (CET) (envelope-from ticso) Date: Thu, 7 Feb 2008 23:06:16 +0100 From: Bernd Walter To: Dieter Message-ID: <20080207220616.GJ24583@cicely12.cicely.de> References: <20080207162120.GG24583@cicely12.cicely.de> <200802071752.RAA13888@sopwith.solgatos.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200802071752.RAA13888@sopwith.solgatos.com> X-Operating-System: FreeBSD cicely12.cicely.de 5.4-STABLE alpha User-Agent: Mutt/1.5.9i X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED=-1.8, BAYES_00=-2.599 autolearn=ham version=3.2.3 X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on cicely12.cicely.de Cc: freebsd-alpha@freebsd.org Subject: Re: DS10L - "processor correctable error" X-BeenThere: freebsd-alpha@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: ticso@cicely.de List-Id: Porting FreeBSD to the Alpha List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Feb 2008 22:06:26 -0000 On Thu, Feb 07, 2008 at 09:52:54AM +0000, Dieter wrote: > > > > > "Warning: received processor correctable error." > > > > > This is an ECC memory correction. > > > > Can I know which DIMM (DS10L has 2 DIMMs) is faulty? > > > > The message appears approx. once every other pass. > > > The address is always the same. > > If you decide to replace one, you could pick one at random and > see if the error goes away. Since your error is repeatable > you can run the test to see if you guessed right. Since there > are only 2 DIMMs you have a 50% chance of guessing right the 1st > time and 100% the 2nd time. > > > Alphas are using the memory in pairs and can correct multiple faulty > > bits in a single dataword. > > Really? I've always assumed that it was the standard single error > correction double error detection. It uses at least 128bit words - some alphas even uses 256 bit words. so there are 16 or even 32 bits for ECC and this allows correcting more than just a single bit. (some?) Alphas use a multi stage correction mechanism. The first stage is done in hardware and if the hardware fails to handle it, it is done in software by a palcode handler. Maybe even some non alpha systems do multi bit correction, since a modern i386/amd64 has at least 8bit for ECC, but I only know it for sure with alphas. -- B.Walter http://www.bwct.de http://www.fizon.de bernd@bwct.de info@bwct.de support@fizon.de