NAND flash file system and JFFS2 problem

[Josh Boyer]

On Thu, 2007-03-22 at 09:26 +0100, Jakub Bednář wrote:
> Hi,
>       I've spent long time reading all about mtd devices and I'd like 
> to check if I understood correctly.
> 
> 1.) The NFTL is usable ONLY for DOC, not for normal NAND flashes.
>       Thats why nftl_format prints unrecognized erase size 0x20000

Yes.

> 2.) FTL is usable ONLY with NOR flashes, that's why the ftl_format
>        ends with an error on trying to erase bad block on NAND in dmesg.

Not sure, but I think yes.

> 3.) So there should be used JFFS2 on NAND, there is no good and reliable
>        way to run ext2 on NAND.

Correct.  Yaffs can also work on NAND.

> I've also encountered a problem.
>         I'm using kernel 2.6.16.20 from buildroot on DBAu1550 like board.
>         When running destroy test on Samsung NAND where I had ext2, 
>         I was using programs from busybox placed on NOR flash (jffs2) /dev/mtdblock0. 
>         Links like dd, cp, md5sum.
> 
>         NAND was mounted on /mnt/. After creating a 45MB file /mnt/file0 with dd
>         from /dev/zero  and running md5sum, something got wrong and all the links
>         from NOR jffs2 stopped working with lot's of errors in CRC codes. I wasnt writting
>         to the NOR jffs2 but I have it mounted rw.  After rebooting the NOR jffs2 is ok again!
> 
>         So maybe it mess up in RAM???  What can couse this trouble?

That seems very odd.  Unfortunately, I don't have an idea at the moment.

josh