From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from top.free-electrons.com ([176.31.233.9] helo=mail.free-electrons.com) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VbxB2-00088u-Sd for linux-mtd@lists.infradead.org; Thu, 31 Oct 2013 18:41:05 +0000 Date: Thu, 31 Oct 2013 15:40:46 -0300 From: Ezequiel Garcia To: Konstantin Tokarev Subject: Re: Flashing UBIFS image to gluebi mtd Message-ID: <20131031184045.GA2498@localhost> References: <72811383227314@web24j.yandex.ru> <20131031150844.GA1092@localhost> <16161383242430@web27h.yandex.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <16161383242430@web27h.yandex.ru> Cc: "linux-mtd@lists.infradead.org" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Oct 31, 2013 at 10:00:30PM +0400, Konstantin Tokarev wrote: > > > 31.10.2013, 19:08, "Ezequiel Garcia" : > > Hi Konstantin, > > > > On Thu, Oct 31, 2013 at 05:48:34PM +0400, Konstantin Tokarev wrote: > > > >>  I'm migrating rootfs of device from SquashFS on top of gluebi to UBIFS. > > > > Sounds like you could use ubiblock for that setup, which is suitable > > for squashfs, and completely independent of ubifs (thus less cpu and > > memory hungry and easier to setup). > > Could you elaborate this a bit more? Do you mean that block device emultaion > layer on top of UBI + FS on top of that can work faster than UBIFS on top of > UBI? > Given you provided no details, I'm not sure why you're migrating from squashfs (which is a read-only, block oriented fs) to ubifs (which supports r/w on MTD). But anyway, let me do this homework for you :-) So, you had squashfs on top of gluebi, right? I guess you had this: mtd (plus your NAND driver) -> ubi -> gluebi/mtd -> mtdblock -> squashfs On the other side, using ubiblock to emulate the block device you'd end up with this: mtd (plus your NAND driver) -> ubi -> ubiblock -> squashfs Which is less memory (cpu?) hungry than the first alternative. The latest git branch also contained a non-cached option which has shown some good behavior, given squashfs does its own caching. But of course, this is _NOT_ a replacement for UBIFS, and using ubiblock for R/W is strictly discouraged. And here's the (already ancient) discussion: http://lists.infradead.org/pipermail/linux-mtd/2012-November/045011.html And the v2: http://lists.infradead.org/pipermail/linux-mtd/2012-December/045274.html I'll post the latest work as soon as I find some time, but you're free to pursue your own research. Hope it helps and best of lucks! -- Ezequiel García, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com