From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20142 invoked by alias); 23 Sep 2005 13:33:17 -0000 Mailing-List: contact ecos-devel-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: ecos-devel-owner@ecos.sourceware.org Received: (qmail 20082 invoked by uid 22791); 23 Sep 2005 13:33:07 -0000 Received: from sta-204-188-98-138.rockynet.com (HELO hermes.chez-thomas.org) (204.188.98.138) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Fri, 23 Sep 2005 13:33:07 +0000 Received: by hermes.chez-thomas.org (Postfix, from userid 2000) id 057FC2C8855EC; Fri, 23 Sep 2005 07:32:45 -0600 (MDT) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by hermes.chez-thomas.org (Postfix) with ESMTP id 3F1002C885574; Fri, 23 Sep 2005 07:32:43 -0600 (MDT) Subject: Re: contributing filesystem and a failsafe update meachanism for FIS from within ecos applications From: Gary Thomas To: ml.ecos@ringle.org Cc: eCos development In-Reply-To: <200509230901.09267.ml.ecos@ringle.org> References: <5A8A17126B73AC4C83968F6C4505E3C502BE67C5@JO-EX01.JENOPTIK.NET> <200509230901.09267.ml.ecos@ringle.org> Content-Type: text/plain Organization: MLB Associates Date: Fri, 23 Sep 2005 13:33:00 -0000 Message-Id: <1127482362.26556.146.camel@hermes> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-3) Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 3.0.0 (2004-09-13) on hermes.chez-thomas.org X-Spam-Level: X-Spam-Status: No, score=-5.9 required=3.0 tests=ALL_TRUSTED,BAYES_00 autolearn=ham version=3.0.0 X-SW-Source: 2005-09/txt/msg00007.txt.bz2 On Fri, 2005-09-23 at 09:01 -0400, Jon Ringle wrote: > On Friday 23 September 2005 08:09 am, Neundorf, Alexander wrote: > > 5. after the image is written, set the valid_flag of the fis directory > > which will become active to 0xa5a5. In order to do this, the flash block > > doesn't have to be erased, since the transition from 0xfdfd to 0xa5a5 only > > sets some bits to 0. > > I didn't know this property of flash. Is this a universal property of NOR > flash? Yes. Erase operations reset all the bits to one. Programming can only change a one to a zero. This can be done on a bit by bit basis, thus you can update a block by changing some bits to zeroes without having to erase it. -- ------------------------------------------------------------ Gary Thomas | Consulting for the MLB Associates | Embedded world ------------------------------------------------------------