From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from majordomo by infradead.org with local (Exim 3.20 #2) id 14TMo0-0004Jn-00 for mtd-list@infradead.org; Thu, 15 Feb 2001 11:42:36 +0000 Received: from dell-paw-3.cambridge.redhat.com ([195.224.55.237] helo=passion.cambridge.redhat.com) by infradead.org with esmtp (Exim 3.20 #2) id 14TMny-0004Jh-00 for mtd@infradead.org; Thu, 15 Feb 2001 11:42:35 +0000 From: David Woodhouse In-Reply-To: <200102151111.DAA02064@concorde.cs.ucla.edu> References: <200102151111.DAA02064@concorde.cs.ucla.edu> To: Jeremy Elson Cc: jffs-dev@axis.com, mtd@infradead.org Subject: Re: Does JFFS respect partitions? Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Thu, 15 Feb 2001 11:41:47 +0000 Message-ID: <1018.982237307@redhat.com> Sender: owner-mtd@infradead.org List-ID: jelson@ISI.EDU said: > Interesting - I didn't realize the DOC did internal wear-levelling. The DiskOnChip doesn't. It's just a bunch of flash chips with a clever ASIC to multiplex them and do some ECC in hardware. The NFTL psuedo-filesystem does. In software. > I guess that might mean that there's no point in using JFFS on top of > the NTFL layer anyway? True. > > It's also possible to register the DiskOnChip raw flash as two > > separate MTD devices, which is how we 'partition' normal flash. Then > > you let the NFTL code put a filesystem on one of them and use JFFS > > on the other. > This sounds ideal - how does one do this? You need to get your hands dirty. See the 'add_mtd_partitions' code in mtdpart.c and some of the drivers which call it - basically you have an underlying MTD device (the DiskOnChip) and you define two dummy devices which just add an offset to the address requested and pass through to the 'real' device's methods. It's probably better to take the other route I suggested - have two NFTL partitions on the DiskOnChip. Clever offset/len args to nftl_format will do that. The NFTL code ought to be OK with it, and it shouldn't be difficult to fix if it isn't. > I don't know the intricacies of the existing jffs2 code or what's left > to implement, but, will a broomstick speed things up for you? :-) Heh - maybe. But stupid quantities of caffeine seem to be working OK at the moment. -- dwmw2 To unsubscribe, send "unsubscribe mtd" to majordomo@infradead.org