From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.nokia.com ([192.100.105.134] helo=mgw-mx09.nokia.com) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1JpLXr-0002t2-Mu for linux-mtd@lists.infradead.org; Fri, 25 Apr 2008 10:52:48 +0000 Message-ID: <4811B6BF.9020200@nokia.com> Date: Fri, 25 Apr 2008 13:47:27 +0300 From: Adrian Hunter MIME-Version: 1.0 To: ext Nancy Subject: Re: UBI: badblock management confusion! References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-mtd List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , ext Nancy wrote: > Hi all, > I don't quite understand the UBI badblock management unit. > But I think there must be something wrong, or I take a wrong operation. > Please follow my test below: > > # ubiformat /dev/mtd5 > ubiformat: mtd5 (NAND), size 536870912 bytes (512.0 MiB), 262144 eraseblocks of > 262144 bytes (256.0 KiB), min. I/O size 2048 bytes > libscan: scanning eraseblock 2047 -- 100 % complete > ubiformat: 2045 eraseblocks have valid erase counter, mean value is 23 > ubiformat: bad eraseblocks: 10, 40, 84 > ubiformat: formatting eraseblock 2047 -- 100 % complete > > # modprobe ubi mtd=5 > UBI: physical eraseblock size: 262144 bytes (256 KiB) > UBI: logical eraseblock size: 258048 bytes > UBI: smallest flash I/O unit: 2048 > UBI: VID header offset: 2048 (aligned 2048) > UBI: data offset: 4096 > UBI: attached mtd5 to ubi0 > UBI: MTD device name: "NAND VFAT partition" > UBI: MTD device size: 512 MiB > UBI: number of good PEBs: 2045 > UBI: number of bad PEBs: 3 > UBI: max. allowed volumes: 128 > UBI: wear-leveling threshold: 256 > UBI: number of internal volumes: 1 > UBI: number of user volumes: 0 > UBI: available PEBs: 2021 > UBI: total number of reserved PEBs: 24 > UBI: number of PEBs reserved for bad PEB handling: 20 > UBI: max/mean erase counter: 38/24 > UBI: background thread "ubi_bgt0d" started, PID 233 > > *************************************************************************** > I'm going to make one big volume which take all available space this ubi > device has. > > I think the volume size should be equal to > (total number of PEB this ubi device has - total number of reserved PEBs) \ > * LEB size > In this case, it should be : (2048-24) * 258048 bytes > > But that is not what UBI count. > UBI think the volume size > = (number of good PEBs - total number of reserved PEBs) * LEB size > > Q: Number of bad PEBs at initialization are not included in resered for bad > PEBs handling. That mean there should never has badblocks overflow issue > happen. What a good idea! But is there really a possible way to implement this > idea? It does work. > Suppose there's only one volume take all the ubi device space, there's no > badblocks at the very beginning. The user does never shut down the device but > hibernate for a long time. Then, suppose there is 3 badblocks and the volume > just full of data. No space left. Then reboot the device, beside the 3 badblocks > which used to be count in reserved PEBs, now be seperate from the reserved PEBs, > But there's no space, reserved PEB will fail. No, there will just be a warning - as shown in your test: UBI warning: ubi_eba_init_scan: cannot reserve enough PEBs for bad PEB handling, reserved 19, need 20 There *would* be problem if you marked 21 bad and only 20 were reserved for bad block handling. > > The following test showes even the volume data is blank, there still comes > problem. > Is it an UBI bug or my wrong operation? Your wrong operation. > Thanks for your notice about it! > **************************************************************************** > > # ubimkvol /dev/ubi0 -n 0 -N vfat -s 509292KiB > Volume ID 0, size 2021 LEBs (521515008 bytes, 497.4 MiB), LEB size > 258048 bytes (252.0 KiB), dynamic, name "vfat", alignment 1 > # rmmod ubi > UBI: mtd5 is detached from ubi0 > > ***************************************************************************** > "markbadblock" is a tool I force to mark a block bad manually, just for test > ***************************************************************************** > # markbadblock -l 17 /dev/mtd5 > Block size 262144, page size 2048, OOB size 64 > mark block 17 to be badblock done > > # modprobe ubi mtd=5 > UBI: physical eraseblock size: 262144 bytes (256 KiB) > UBI: logical eraseblock size: 258048 bytes > UBI: smallest flash I/O unit: 2048 > UBI: VID header offset: 2048 (aligned 2048) > UBI: data offset: 4096 > UBI warning: ubi_eba_init_scan: cannot reserve enough PEBs for bad PEB > handling, reserved 19, need 20 > UBI: attached mtd5 to ubi0 > UBI: MTD device name: "NAND VFAT partition" > UBI: MTD device size: 512 MiB > UBI: number of good PEBs: 2044 > UBI: number of bad PEBs: 4 > UBI: max. allowed volumes: 128 > UBI: wear-leveling threshold: 256 > UBI: number of internal volumes: 1 > UBI: number of user volumes: 1 > UBI: available PEBs: 0 > UBI: total number of reserved PEBs: 2044 > UBI: number of PEBs reserved for bad PEB handling: 19 > UBI: max/mean erase counter: 39/24 > UBI: background thread "ubi_bgt0d" started, PID 263 > # modprobe ubifs > > # mount -t ubifs ubi0:ubifs /mnt/1 > UBIFS error (pid 293): ubifs_get_sb: cannot open "ubi0:ubifs", error -19 You named the volume "vfat" (-N option of ubimkvol), but you are trying to mount a volume named "ubifs" i.e. should be: mount -t ubifs ubi0:vfat /mnt/1 > mount: mounting ubi0:ubifs on /mnt/1 failed: No such device > # rmmod ubifs > # rmmod ubi > > # ubiformat /dev/mtd5 > ubiformat: mtd5 (NAND), size 536870912 bytes (512.0 MiB), 262144 eraseblocks of > 262144 bytes (256.0 KiB), min. I/O size 2048 bytes > libscan: scanning eraseblock 2047 -- 100 % complete > ubiformat: 2044 eraseblocks have valid erase counter, mean value is 24 > ubiformat: bad eraseblocks: 10, 17, 40, 84 > ubiformat: formatting eraseblock 2047 -- 100 % complete >