From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17615 invoked by alias); 16 May 2009 12:50:18 -0000 Received: (qmail 17607 invoked by uid 22791); 16 May 2009 12:50:17 -0000 X-SWARE-Spam-Status: No, hits=-1.3 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Received: from hagrid.ecoscentric.com (HELO mail.ecoscentric.com) (212.13.207.197) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 16 May 2009 12:50:08 +0000 Received: from localhost (hagrid.ecoscentric.com [127.0.0.1]) by mail.ecoscentric.com (Postfix) with ESMTP id C045A3B40054; Sat, 16 May 2009 13:50:05 +0100 (BST) Received: from mail.ecoscentric.com ([127.0.0.1]) by localhost (hagrid.ecoscentric.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bMtqHFQtKONT; Sat, 16 May 2009 13:50:03 +0100 (BST) Received: from alabaster.local (60.66.187.81.in-addr.arpa [81.187.66.60]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: wry@ecoscentric.com) by mail.ecoscentric.com (Postfix) with ESMTP id 837893B40030; Sat, 16 May 2009 13:50:02 +0100 (BST) Message-ID: <4A0EB6C5.3020005@ecoscentric.com> Date: Sat, 16 May 2009 12:50:00 -0000 From: Ross Younger User-Agent: Thunderbird 2.0.0.21 (Macintosh/20090302) MIME-Version: 1.0 To: Andrew Lunn CC: John Dallaway , ecos-maintainers@ecos.sourceware.org, Rutger Hofman , Simon Kallweit , Sergei Gavrikov Subject: Re: NAND & YAFFS References: <4A0AD212.60208@ecoscentric.com> <4A0B198F.6020109@dallaway.org.uk> <4A0D9D4D.6070308@ecoscentric.com> <20090516104332.GE31991@ma.tech.ascom.ch> In-Reply-To: <20090516104332.GE31991@ma.tech.ascom.ch> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Mailing-List: contact ecos-maintainers-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: ecos-maintainers-owner@ecos.sourceware.org X-SW-Source: 2009-05/txt/msg00020.txt.bz2 Hi Andrew, > Im having trouble getting my head around partitions. > > If i understand the documentation correctly, the only thing the > concept does it prevent a buggy filesystem or application reading data > from a different partition than it "opened" with > cyg_nand_get_partition(). The partition has zero affect on addressing. > > Am i missing something? What else are partitions good for? Partitions may be a bit of a misleading term for it, but it's the best I could come up with. It seems quite common for boards (both dev boards, and deployed products) to have a single NAND device or array, carved up into two (or more) separate filesystems. As you observe, addressing is completely unaffected, and this is based on my observations of other devices; I added in the boundary enforcement purely out of paranoia. To take the example of the embedded Linux world, typically the primary boot loader uses the filesystem on the first partition (think of it as "/boot") to get a kernel or application image, which then uses the second (much larger) partition as its root filesystem. These two partitions could be the same filesystem, or the boot partition could be something simpler to simplify the boot loader. Also, having the partition information in one place means that filesystems can read out their limits from it, rather than having to be configured separately. Ross -- eCosCentric Ltd, Barnwell House, Barnwell Drive, Cambridge CB5 8UU, UK Registered in England no. 4422071. www.ecoscentric.com