From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 1wt.eu ([62.212.114.60]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Vdi5h-0004l8-TF for linux-mtd@lists.infradead.org; Tue, 05 Nov 2013 14:58:50 +0000 Date: Tue, 5 Nov 2013 15:57:48 +0100 From: Willy Tarreau To: Ezequiel Garcia Subject: Re: Ubiblock users call (Re: mvneta / openblocks switch) Message-ID: <20131105145748.GE17316@1wt.eu> References: <20131031135322.GN26784@titan.lakedaemon.net> <52738D6A.1010900@hitachi.com> <20131101130528.716e53d9@skate> <20131105103555.GD16420@1wt.eu> <5278E824.8050405@hitachi.com> <20131105135323.GA17316@1wt.eu> <20131105144003.GB9632@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131105144003.GB9632@localhost> Cc: piergiorgio.beruto@gmail.com, Mike Frysinger , linux-mtd@lists.infradead.org, Artem Bityutskiy List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Ezequiel, On Tue, Nov 05, 2013 at 11:40:04AM -0300, Ezequiel Garcia wrote: > On Tue, Nov 05, 2013 at 02:53:23PM +0100, Willy Tarreau wrote: > > > > > > Hmm, could you tell me which github branch is good to try? > > [...] > > > > > then I have set up a large collection of patches, including Ezequiel's work > > on the NAND flash, his UBI block devices and > [...] > > Hey Willy, > > Which patches have you taken for UBI block device? I found a patch you posted on a list (probably linux-mtd but I'm not certain) which received very little feedback. I wanted to give it a try and found that it was easy to integrate and that it worked fine out of the box. > Can you describe your usage? I wanted to avoid ubifs for having used too many non-recoverable FS corruptions with it in the past (most likely due to a faulty NAND in the iomega Iconnect, or at least problems with the timings). More importantly, seeing that there is no fsck equivalent for it is not something to reassure me, because each time I got an issue, it was not possible to remount the FS nor to fix it and everything was lost. Still, I like the idea of UBI and wanted to experiment with something like this to offer a block device interface. And before starting any work, I googled around, thinking "probably someone will already have had this idea". I found your patch and gave it a try. I only played with it for one evening and did not have any more time to power my mirabox on since. But I see some potential in it. Having the ability to support partitions, various FS types, etc... makes it easier to migrate systems designed to work this way to NAND-based devices. This is probably also one reason for the success of eMMC which tends to replace raw NAND on some new boards. For example, one of my distro's boot scripts automatically detects the available partitions, checks for a mountable FS there, then locates the current config and loads it. With a block device, I have nothing to change at all. With other solutions, I have to reconsider the boot process. > I've been wanting to push this upstream since a long while, and the patches > seem ready. However, given I'm not using these *at all*, I'd like to have some > real users supporting the feature addition. I definitely am a supporter. It's still too early for me to judge whether the design is the best one or not, but the feature of presenting a reliable block device on top of a NAND is clearly appealing to make NAND-based devices work more similarly to other devices found in the x86 world and reduce the porting effort. I was a bit sad to see that your work received to little feedback, and am ashamed for not having sent you any since (nor retried your two latest pxa3xx patch series). > Just for reference, the latest work is here: > > http://git.free-electrons.com/users/ezequiel-garcia/linux/log/?h=ubiblock-v4-two-cache > > And the user stuff: > > http://git.free-electrons.com/users/ezequiel-garcia/mtd-utils/log/?h=ubiblkvol Ah excellent, thank you for the links! One thing I noticed is that my mirabox's u-boot is able to read and write an UBI volume, but IIRC, it can read what I format from linux but if I write from u-boot, the linux cannot reread it. That's where I remember it was late in the night and I had to go back home, then I haven't had an opportunity to try again since. I would find it really convenient to be able to ubi-write a block image from u-boot and read it from Linux using the same format. It would ease the (re)installation process making abstraction of bad blocks. Best regards, Willy