From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-gw0-f49.google.com ([74.125.83.49]) by casper.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1Qa827-0004Xq-Nv for linux-mtd@lists.infradead.org; Fri, 24 Jun 2011 15:11:01 +0000 Received: by gwb1 with SMTP id 1so1369599gwb.36 for ; Fri, 24 Jun 2011 08:10:07 -0700 (PDT) Message-ID: <4E04A8C4.8000206@gmail.com> Date: Fri, 24 Jun 2011 11:09:56 -0400 From: Peter Barada MIME-Version: 1.0 To: Ivan Djelic Subject: Re: Preventing JFFS2 partial page writes? References: <4DF789FC.1030305@gmail.com> <1308722655.18119.40.camel@sauron> <4E020A36.6070708@gmail.com> <20110622170747.GC25928@parrot.com> <4E023FCD.9010800@gmail.com> <20110622200621.GA26973@parrot.com> In-Reply-To: <20110622200621.GA26973@parrot.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "linux-mtd@lists.infradead.org" , "dedekind1@gmail.com" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 06/22/2011 04:06 PM, Ivan Djelic wrote: > On Wed, Jun 22, 2011 at 08:17:33PM +0100, Peter Barada wrote: >> On 06/22/2011 01:07 PM, Ivan Djelic wrote: >>> On one hand it sure would be nice (and a bit complicated) to accurately >>> describe OOB write constraints, for easier JFFS2/YAFFS2 integration. >>> On the other hand, I am not sure such a complication is really worth the >>> trouble, given that on next nand generation: >>> - OOB areas will not be usable anymore for metadata storage (8-bit ecc leaves >>> only 6 spare bytes out of 64) >>> - partial writes will probably be limited to 1 (like in MLC), meaning that >>> JFFS2 clean marking step will be forbidden anyway >>> Furthermore, userspace will probably need to handle case 3) anyway (no >>> protected oob bytes) to stay portable... >>> >> SLC parts (including this one) look to be around for a while, as well as >> the products they are already in. So I think the issue of JFFS2's >> cleanmarker in the context of this Micron NAND needs to be solved, >> preferably in a general way so the next oddball NAND chip that comes >> along doesn't cause MTD, mtd-utils, JFFS2 (and other NAND FS) fits. >> >> Does UBIFS do any of the "partial writes" (i.e. write OOB/data area >> multiple times) as JFFS2 does? > > No it doesn't. UBIFS relies on UBI, which itself does not rely on oob for > storing metadata. BTW, have you considered using UBIFS instead of JFFS2/YAFFS2? Yes. However customers are already using JFFS2/YAFFS2 and are reluctant to change. > -- > Ivan > > ______________________________________________________ > Linux MTD discussion mailing list > http://lists.infradead.org/mailman/listinfo/linux-mtd/ -- Peter Barada peter.barada@gmail.com