From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out.bhp.t-online.de ([195.145.119.39]) by pentafluge.infradead.org with esmtp (Exim 4.14 #3 (Red Hat Linux)) id 191Nok-0005LG-KU for ; Fri, 04 Apr 2003 10:49:02 +0100 Received: from maria.bhp.t-online.de (maria.ada.t-online.de [172.30.8.41]) 21 2002)) with SMTP id <0HCT003MKCKW2R@smtp-out.bhp.t-online.de> for linux-mtd@lists.infradead.org; Fri, 04 Apr 2003 11:48:33 +0200 (MEST) Date: Fri, 04 Apr 2003 12:48:57 +0200 From: Thomas Gleixner In-reply-to: <20030404062136.7806.qmail@vip.sina.com> To: jimzeus@vip.sina.com, linux-mtd@lists.infradead.org Message-id: <200304041248.57751.tglx@linutronix.de> MIME-version: 1.0 References: <20030404062136.7806.qmail@vip.sina.com> Content-type: text/plain; charset=iso-8859-15 Content-transfer-encoding: 7BIT Subject: Re: [SPAM] FAT on NAND Reply-To: tglx@linutronix.de List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Friday 04 April 2003 08:21, jimzeus@vip.sina.com wrote: > What I am doing now is to build a filesystem which can be > recognized on _raw_ NAND flash. So, I think FAT will be the only > choice(though I know it's very unstable). And I have following question > now: For what ? Why don't you use JFFS2 or YAFFS, which handle NAND out of the box ? > 1.How unstable would it be? Does it support: > a.journaling (crash/power-off safe ,I mean) > b.bad block management > c.wear levelling > d.error correction > e.something else I dont know to make the FS reliable JFFS2 and YAFFS have all this, read the source and build a new one, if you have enough time. > 2.I have checked the NAND flash docoment (especially > the "Filesystems supporting NAND"chapter) and I found out that > it seems no way to build a FAT on a bare NAND flash but only on > the SmartMediaCards, am I right? Or the SM card and the bare NAND > are just the same thing when a FAT on it. SMCard and bare NAND is just the same, only packaging is different > 3.Maybe I misunderstood,but David Woodhouse had told me that I should apply > layers like FAT->NFTL->NAND if I wanna build a FAT on a NAND flash.But I > learned that the NFTL only support Doc from the NAND flash document, isnt > it? And what should I do to support the > FAT ? Hack NTFL :) > 4.Everybody tells me that the Fat on a NAND is not reliable,but I > think USB mass storage are based on NAND and got a FAT (or some > filesystem which windows can recognize) on it, so ,how comes it > happen? Yes, this is Smart-Media-FAT, which is not exactly the same as DOS-FAT. SmartMedia-FAT is used on SmartMedia cards for MP3-Players, Digicams ... There exist various adapters (USB, serial, LPT) to access it via a PC. SmartMedia-FAT is designed for NAND-FLASH and handles bad block management and error correction. If you want compability to this, you have to write a fs-driver, which is compatible to the SMART-Media-FAT definition, which is available from Toshiba under a non disclosure aggreement. -- Thomas ________________________________________________________________________ linutronix - competence in embedded & realtime linux http://www.linutronix.de mail: tglx@linutronix.de