On 09/20/2013 11:27 AM, ANDY KENNEDY wrote: >> -----Original Message----- >> From: u-boot-boun...@lists.denx.de [mailto:u-boot-boun...@lists.denx.de] On >> Behalf Of Peter Barada >> Sent: Thursday, September 19, 2013 3:26 PM >> To: u-boot@lists.denx.de; Peter Barada >> Subject: Re: [U-Boot] NAND flash question >> >> On 09/19/2013 04:04 PM, ANDY KENNEDY wrote: >>> All, >>> >>> We have a design that has NAND as a secondary device (not the boot >>> device). The last four pages of the NAND flash are reported as bad. >>> Should this be true for all NAND flash devices we have? >>> >>> >> No, I wouldn't think so. Manufacturers qualify their parts and mark bad >> blocks found during qualification testing. Most data sheets indicate >> that the number of bad blocks marked bad during manufacturer is below a >> set percentage(if above thent he part is rejected). Some parts that are >> meant to be used during boot (such as NAND meant for OMAP parts) will >> have certain blocks that are guaranteed good (i.e. the boot blocks). >> Past that bad blocks could be anywhere in a particular device. >> > Okay, well, next question: So on EVERY unit we have designed with a > NAND flash, when u-Boot reads the NAND flash it reports that it couldn't > locate a bad block table and states that it cannot read the last four > pages of the flash. Next, when one does a 'nand bad' on these boards, > these last four pages are reported by u-Boot as bad. Looking at the > code, we believe that this is by design. Is that correct? Has anyone > else done a 'nand bad' on a board and seen the same information? > > Thanks again for any information you can provide, > > Andy If you are using a NAND-based bad block table (i.e. set the NAND_USE_FLASH_BBT bit in nand->options), then the MTD layer will internally use the last four blocks to hold the bad block table _and_ report those blocks as bad to prevent the user from accidentally modifying them...
-- Peter Barada peter.bar...@logicpd.com _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
