From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from majordomo by infradead.org with local (Exim 3.16 #2) id 13SIOx-0000hY-00 for mtd-list@infradead.org; Fri, 25 Aug 2000 13:16:03 +0100 Received: from dns.cygnus.co.uk ([194.130.39.3] helo=pasanda.cygnus.co.uk) by infradead.org with smtp (Exim 3.16 #2) id 13SIOw-0000hS-00 for mtd@infradead.org; Fri, 25 Aug 2000 13:16:02 +0100 From: David Woodhouse In-Reply-To: <000801c00e8b$9a649560$0800a8c0@win95.inteloop.se> References: <000801c00e8b$9a649560$0800a8c0@win95.inteloop.se> To: mdeans@algonet.se Cc: mtd@infradead.org, mark.langsdorf@amd.com Subject: Re: Anyone using mtd on NAND flash? (Was: The archives [looking for info on AM29LV640 flash]) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 25 Aug 2000 13:15:59 +0100 Message-ID: <15725.967205759@cygnus.co.uk> Sender: owner-mtd@infradead.org List-ID: bjorn@brannstrom.se said: > I've just been across the hall to strangle our hardware engineer (who > happens to also be my boss). He /intended/ to use the AM29LV640 part > but had problems finding a reliable source for them so we're using > Samsungs KM29U128 part instead. Don't strangle him. Have him hung, drawn and quartered. The KM29U128 is an _entirely_ different beast. NAND flash is quite different to NOR flash. With NOR flash, you can keep clearing bits individually until they're all zero. With NAND flash you can only do 10 write cycles in each 512-byte page before it becomes unreliable and you have to erase it again. JFFS currently exceeds that number. Also, NAND flash is permitted to ship with bad blocks and you're expected to work round them. JFFS doesn't, and JFFS-on-NAND should probably use an error correcting checksum rather than the simple checksum it currently uses. He's just replaced something you could use with the current code with something we're not going to support for some time, unless you care to do the necessary work yourself. You can't use NFTL, as we do on the DiskOnChip, because it's patented, and even if you were only going to distribute within the Free World, the NFTL code requires the built-in ECC support provided by the DiskOnChip ASIC. -- dwmw2 To unsubscribe, send "unsubscribe mtd" to majordomo@infradead.org