On Wednesday 25 July 2007 12:22, you wrote:
> I set that option in the hope that when upgrading a device in
> the field (with k 2.4 and old_yaffs) the contents of the yaffs
> file system would be preserved.
>
> Perhaps that is not even possible???

Oh, it is possible, that's why we have the option.

If you really want it to work however you also need to change MTD 
to use the same OOB and ECC layout that you had with your old 
2.4 kernel setup. This requires your nand 'driver' to setup a 
custom nand_ecclayout when you create your mtd master device. 
See the comment/sample nand_ecclayout in yaffs_mtdif1.c and the
default layout in MTD's nand_base.c.

In your first posting you said you were using a 2.6.17.14 -- this 
was a time of change for MTD NAND. You may want to scrutinize 
the api calls between yaffs and MTD. Also pull a few MTD 
nand_base.c fixes back to your kernel if you have a version of 
MTD that includes the struct mtd_oob_ops arguments to the NAND 
read/write calls.

-imcd