From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [212.18.0.9] (helo=mail-out.m-online.net) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NNYwi-0003sk-Qm for linux-mtd@lists.infradead.org; Wed, 23 Dec 2009 21:40:45 +0000 To: "Darwin Rambo" From: Wolfgang Denk Subject: Re: UBI - exclude bootloader blocks from wear levelling MIME-Version: 1.0 Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 8bit In-reply-to: References: <4B2FA658.6010407@wyplay.com> <20091223063242.B63923F6EF@gemini.denx.de> Date: Wed, 23 Dec 2009 22:40:01 +0100 Message-Id: <20091223214001.815CD3F6EF@gemini.denx.de> Cc: "linux-mtd@lists.infradead.org" , Lauren Del Giudice List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Dear "Darwin Rambo", please do not top-post / full qoute. See http://www.netmeister.org/news/learn2quote.html In message you wrote: > I think Lauren must have been referring to a bootloader that lives > outside the kernel and file system context. For example, a small, > standalone bootloader downloaded from a serial port to it's own > partition, would not be known to the kernel, as it is used to launch > the kernel or later stage bootloaders. In this case it runs > standalone and can't sit on UBI or be launched by a linux app. If Of course it can, assuming it is UBI-aware by itself. For example, U-Boot is such a boot loader that can load the U-Boot image itself from a UBI partition in NAND. > this small bootloader was only a block or two in size, and since it > is typically burned once for production and then becomes read-only > for each bootup after that, wear levelling is not required or > possible. Noite that "read-only" is not sufficient. NAND flash will develop errors even if you just read it often enough. See for example this Micron Application Note: http://download.micron.com/pdf/technotes/nand/tn2917.pdf > Flash data retention periods are usually specified in years, and I am not talking about "data retention" here. See section "NAND Flash is Not a Hard Drive" in the above Application Note to understand what I mean. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de Defaults are wonderful, just like fire. - Larry Wall in <1996Mar6.004121.27890@netlabs.com>