From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-gy0-f177.google.com ([209.85.160.177]) by canuck.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1QZSvo-0006UA-SG for linux-mtd@lists.infradead.org; Wed, 22 Jun 2011 19:17:47 +0000 Received: by gyh4 with SMTP id 4so551933gyh.36 for ; Wed, 22 Jun 2011 12:17:40 -0700 (PDT) Message-ID: <4E023FCD.9010800@gmail.com> Date: Wed, 22 Jun 2011 15:17:33 -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> In-Reply-To: <20110622170747.GC25928@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 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? -- Peter Barada peter.barada@gmail.com