On Wednesday 13 April 2011 23:27:25 Nick Thompson wrote:
> On 13/04/11 11:48, Nick Thompson wrote:
> > yaffs [master] snapshot from today, linux 2.6.33-rc4
> >
> > I have patched my kernel with yaffs for testing.
> >
> > I did:
> >
> > flash_eraseall /dev/mtd3
> > mount -t yaffs /dev/mtdblock3 /mnt/nand
> > cd /mnt/nand
> > touch test
> > cd ..
> > umount nand
> > mount -t yaffs /dev/mtdblock3 /mnt/nand
> > cd nand
> >
> > ls showed no files (except for lost+found). I turned on logging of erase
> > blocks (YAFFS_TRACE_ERASE) and dmesg showed the following:
> >
> > yaffs: dev is 32505859 name is "mtdblock3" rw
> > yaffs: passed flags ""
> > yaffs: yaffs: Attempting MTD mount of 31.3,"mtdblock3"
> > yaffs: auto selecting yaffs2
> > yaffs: block 2255 is bad
> > yaffs: block 2572 is bad
> > yaffs: block 2574 is bad
> > yaffs: block 3387 is bad
> > yaffs: block 3843 is bad
> > yaffs: block 3845 is bad
> > yaffs: block 4033 is bad
> > yaffs: yaffs_read_super: is_checkpointed 0
> > yaffs: dev is 32505859 name is "mtdblock3" rw
> > yaffs: passed flags ""
> > yaffs: yaffs: Attempting MTD mount of 31.3,"mtdblock3"
> > yaffs: auto selecting yaffs2
> > yaffs: block 2255 is bad
> > yaffs: block 2572 is bad
> > yaffs: block 2574 is bad
> > yaffs: block 3387 is bad
> > yaffs: block 3843 is bad
> > yaffs: block 3845 is bad
> > yaffs: block 4033 is bad
> > yaffs: yaffs_read_super: is_checkpointed 0
> > yaffs: yaffs_block_became_dirty block 1 state 8
> > yaffs: Erased block 1
> >
> > Obviously it didn't like the fist block, which I assumed had my file in
> > it, and decided to erase it.
> >
> > What else should I log to try and figure out what is going on? jffs2 on
> > the same partition passes this same test, so I believe the NAND is work
> > okay.
> >
> > Thanks,
> > Nick. 
>
> Oh and after the first umount the block 1 OOB looks like:
>
>   OOB Data: ff ff 21 00 00 00 02 00 00 00 01 00 00 00 00 08
>   OOB Data: 00 00 2a 00 00 00 01 00 8c 76 51 a2 f0 5d e3 a4
>   OOB Data: 0f 17 6b b2 b6 01 45 8c fd f8 6f 18 6b b2 b6 01
>   OOB Data: 45 8c fd f8 6f 18 6b b2 b6 01 45 8c fd f8 6f 18
>

A raw oob dump tells us nothing.

The flash driver determines how the oob is laid out: which bytes hold bad 
block markers, ECC and are free for usage ( used by yaffs to store tags).

A common screw up in a driver is to have these overlap, resulting in, say, ECC 
bytes being read back as tags.

-- Charles