From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gY841-0000xS-CG for linux-mtd@lists.infradead.org; Sat, 15 Dec 2018 11:24:59 +0000 Date: Sat, 15 Dec 2018 12:24:34 +0100 From: Miquel Raynal To: Steve deRosier Cc: Richard Weinberger , linux-mtd@lists.infradead.org, goliath@sigma-star.at, takei744@oki.com Subject: Re: Questions about ubifs,ubi and mtd? Message-ID: <20181215122434.242cf2bb@xps13> In-Reply-To: References: <1818742.2b902yA6mZ@blindfold> <4423535.My00vEhdVK@blindfold> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Steve, Great summary! Steve deRosier wrote on Thu, 13 Dec 2018 14:22:37 -0800: > On Thu, Dec 13, 2018 at 1:16 PM Richard Weinberger wrote: > > > > Steve, > > > > Am Donnerstag, 13. Dezember 2018, 18:18:49 CET schrieb Steve deRosier: = =20 > > > On Thu, Dec 13, 2018 at 3:36 AM Richard Weinberger w= rote: =20 > > > > > > > > Hello Katsuaki Takei, > > > > > > > > Am Donnerstag, 13. Dezember 2018, 11:45:36 CET schrieb =E6=AD=A6=E4= =BA=95 =E5=85=8B=E6=98=8E: =20 > > > > > Dear Richard, > > > > > > > > > > We appreciate your precious advice. > > > > > We understood the quality status of kernel 3.2.26. > > > > > From now on, we would like to backport from the latest UBI and UB= IFS. > > > > > Do you think that it is enough to backport the next part? > > > > > - drivers/mtd > > > > > - drivers/mtd/ubi > > > > > - fs/ubifs =20 > > > > > > > > Under the assumption that the root of the problem is the MTD/UBI st= ack, > > > > your problem should go away. > > > > =20 > > > > > > Katsuaki Takei, > > > > > > Note that the MTD/UBI stack being at fault is an assumption. There's > > > other things that might be at fault, and in my experience, you usually > > > have multiple problems that all need to be solved. Here's some other > > > possible issues (might not be everything): > > > > > > 1. Does your hardware work? Are you meeting all the setup and hold > > > times on all signals at all times. > > > 2. Does the driver work? Could be a bug, especially a subtle one where > > > it usually works fine, but a missed command makes it unstable. I think this is a very important point, most of the UBI/UBIFS issues that were reported to me were just the consequence of an earlier error that happened at the NAND controller driver level. People reporting bugs tend to only copy/paste the last error they see (which usually is UBI/UBIFS complaining), forgetting about the root cause which has been printed earlier in the dmesg. > > > 3. Does the rest of the MTD/UBI stack work? > > > 4. Is your ECC on the NAND setup right and working? > > > 5. Does whatever hardware or software you're using calculate the ECC > > > bits correctly? For example, on some Atmel processors, there's a bug > > > in the in-ROM PMECC algos so updated software does it in software > > > instead of using the ROM code, but older bootstraps used the ROM algo > > > and thus were bugged. > > > 6. Are you flashing your NAND base image correctly (including getting > > > all the ECC bits in the right place and correct)? > > > 7. When you flash updated images, is that done correctly? > > > 8. During your writing of the filesystem that goes bad, do you write > > > it correctly and sync after each write? Note that 0-size files when > > > you know you wrote something is a key indicator of this problem. > > > 9. When erasing the NAND, you do retain and honor the bad-block marke= rs, yes? > > > > > > Only if the problem's root is in cases 2 and 3 will backporting > > > patches even help. And for the driver case, only if the relevant fix > > > is there. =20 > > > > Thanks a lot for your great summary! > > IMHO it makes sense to put this in form of a checklist to the MTD websi= te. > > What do you think? I also like the idea! Thanks, Miqu=C3=A8l