[PDF] NAND Flash Bad Block Management

Even when new, NAND devices may have bad blocks. A bad block may be a block that has a bit failure or cannot erase properly.

Online forums may recommend use of command called 'nand scrub', which will erase 'bad' markings from BBT and if any application tries to read/write that block ...

Indeed, the U-Boot solution is derived from the MTD implementation. While I understand that factory bad blocks are marked in such a way, isn't

U-Boot only checks for bad block markers in the first two pages of an eraseblock. There is even a flag NAND_BBT_SCANALLPAGES, but it is not the default option.

Is there any user space tool that can retrieve and dump the list of bad blocks in a NAND flash device? I've checked the mtdinfo command line utility.

In Linux , run nandtest -m -p 1 /dev/mtd12, do nothing, reboot to u-boot, nand bad shows that all the NAND blocks of /dev/mtd12 are marked as bad. But if I ...

Nand flash manufactory will mark the bad block with one flag in the spare area of nand flash out of factory. This bad block is what we called initial bad block.

What I am trying to do is test the board to see how many bad blocks it can handle before failing. Is the way I mark the bad blocks correct?

Bad block table support. Most NAND chips mark the bad blocks at a defined position in the spare area. Those blocks must not be erased under any circumstances ...

I'm developing an nand flash driver of u-boot. I think it works well but the environment of u-boot doesn't work properly. Here is what i have done for testing.