From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from b.ns.miles-group.at ([95.130.255.144] helo=radon.swed.at) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WCHH5-0003Pw-Pc for linux-mtd@lists.infradead.org; Sat, 08 Feb 2014 23:25:28 +0000 Message-ID: <52F6BCCD.5070302@nod.at> Date: Sun, 09 Feb 2014 00:25:01 +0100 From: Richard Weinberger MIME-Version: 1.0 To: Willy Tarreau Subject: Re: [PATCH 1/1] ubi: Introduce block devices for UBI volumes References: <1391027881-8354-1-git-send-email-ezequiel.garcia@free-electrons.com> <1391027881-8354-2-git-send-email-ezequiel.garcia@free-electrons.com> <20140208225149.GA22376@1wt.eu> <52F6B602.3030905@nod.at> <20140208230159.GC22376@1wt.eu> <52F6BA07.60707@nod.at> <20140208231501.GG22376@1wt.eu> In-Reply-To: <20140208231501.GG22376@1wt.eu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Thomas Petazzoni , Mike Frysinger , Artem Bityutskiy , Michael Opdenacker , "linux-mtd@lists.infradead.org" , Ezequiel Garcia , Piergiorgio Beruto , Brian Norris , David Woodhouse List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Am 09.02.2014 00:15, schrieb Willy Tarreau: > On Sun, Feb 09, 2014 at 12:13:11AM +0100, Richard Weinberger wrote: >> Am 09.02.2014 00:01, schrieb Willy Tarreau: >>> On Sat, Feb 08, 2014 at 11:56:02PM +0100, Richard Weinberger wrote: >>>> Am 08.02.2014 23:51, schrieb Willy Tarreau: >>>>> On Sat, Feb 08, 2014 at 10:37:19PM +0100, Richard Weinberger wrote: >>>>>>> +config MTD_UBI_BLOCK_WRITE_SUPPORT >>>>>>> + bool "Enable write support (DANGEROUS)" >>>>>>> + default n >>>>>>> + depends on MTD_UBI_BLOCK >>>>>>> + select MTD_UBI_BLOCK_CACHED >>>>>>> + help >>>>>>> + This is a *very* dangerous feature. Using a regular block-oriented >>>>>>> + filesystem might impact heavily on a flash device wear. >>>>>>> + Use with extreme caution. >>>>>>> + >>>>>>> + If in doubt, say "N". >>>>>> >>>>>> I really vote for dropping write support at all. >>>>> >>>>> Why ? When you put a read-only filesystem there such as squashfs, the >>>>> only writes you'll have will be updates, and write support will be the >>>>> only way to update the filesystem. So removing write support seriously >>>>> impacts the usefulness of the feature itself. >>>> >>>> So almost everyone has to enable MTD_UBI_BLOCK_WRITE_SUPPORT? >>>> I thought there is another way to fill the volume with data... >>> >>> I personally don't see the use of disabling write support on anything >>> unless the code is broken. Better emit a warning upon first write to >>> mention that there is limited or no wear leveling. But preventing all >>> reasonable users from using a useful feature just to save a few ignorant >>> from shooting themselves in the foot is non-sense in my opinion. >> >> As Piergiorgio wrote, one can use ubiupdatevol to update his squashfs. >> There is simply no use case for MTD_UBI_BLOCK_WRITE_SUPPORT. > > I gave an example with ext2 for the config. It's a bit excessive to > quickly declare "there is simply no use case for $put_your_option_here", > it just means that *you* don't have this use case, which I perfectly > respect. The mail with your ext2 use case arrived afterward I've sent that mail. So you are using ext2 as config filesystem because you're facing issues with ubifs? Thanks, //richard