Re: Restore the bad block flag in OOB of NAND flash

["Paul Wong" <paul.wong@digitalview.com>]

Thanks  for suggestion. I will try it.

I am using the Samsung 16MB NAND flash . and separate 3 partitions.
/dev/mtd0 is used for kernel img; /dev/mtd1 for general file drive (YAFFS);
/dev/mtd2 for initrd.img. The yaffs driver is compiled by module. and set
"mount -t yaffs /dev/block1 /mnt/flash" in rcS (setup script). No format the
partition in the first mounting.
The drive is not always to use, it is just saved the config. file. So, I
dont clearly know why the yaffs is corrupt. I check the disk space by "du"
command. It said 100% used . And cannot remove any file in this /mnt/flash.
therefore , i think it is corrupted.

Any ideal??

Thank a lot.

Paul

----- Original Message -----
From: "Charles Manning" <manningc2@actrix.gen.nz>
To: "Paul" <paul@maypaul.com>; <linux-mtd@lists.infradead.org>; "yaffs list"
<yaffs@toby-churchill.org>
Sent: Friday, April 18, 2003 4:49 AM
Subject: Re: Restore the bad block flag in OOB of NAND flash


> On Friday 18 April 2003 05:21, Paul wrote:
> >  Dear All,
> >
> >     How can I restore the 0xFF in the OOB[5]?   i understood the oob[5]
is
> >  the bad block indicator. The YAFFS set accidentally the byte to 0x00 .
I
> >  want to use JFFS2 but the eraseall command said they are invalid block.
I
> > am
> >  sure that the block is health . So, I want to force set the oob[5] to
> > oxFF, pls. how can i do? Thank you.
> >
> >  Paul
>
> Generally this is a bad idea to erase bad blocks since destroying factory
> marked bad blocks can cause problems through the entire chip (not just the
> bad block). eg. Some blocks are marked because a write to the block could
> disturb data in another block.
>
> More recent chips seem to have some hardware "fuse" blown to prevent bad
> blocks from being erased.
>
> One way to achieve what you want is to hack mkyaffs. mkyaffs erases the
> blocks in the partition, but first checks for bad block markers. If you
> comment out the check then it will erase the block regardless. This will
set
> all the bits in the block to 1 (including the bad block marker).
>
> BTW: I am curious as to how YAFFS managed to mark your block bad.
>
> -- Charles
>
>
>
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