[Yaffs] YAFFS and ECC questions

Hi,

We've got YAFFS running on Linux 2.6.28.9 running on an AT91SAM9260 based board.
We have a single 512 MB ST Micro NAND chip (64 byte OOB).

We use separate YAFFS/MTD partitions for the linux root fs and the user fs.

I've done a lot of testing, followed the newsgroup for some time and
read through the source code and I have a few questions that need to
be resolved before we launch the product into production.

1. Are there any advantages/disadvantages to mounting a YAFFS
partition read-only?

2. Are ECC error detection, garbage collection and bad block
retirement active for read-only partitions?

3. What happens if there is a spontaneous bit flip error in the 24 MTD
software ECC bytes of the OOB (offset 40-63)?

4. What happens if there is a spontaneous bit flip error in the bad
block bytes of the OOB? Will this mark the entire block as bad the
next time the partition is mounted?

5. In the case of an MTD read that returns ECC_RESULT_UNFIXED, does
the corrupted data persist when the bloc is garbage collected?

6. Does the YAFFS file system's handling of ECC_RESULT_FIXED MTD reads
and the garbage collection algorithm reduce the risk of
ECC_RESULT_UNFIXED MTD reads occurring under a reasonable level?

7. Is there a difference between using MTD soft ECC and YAFFS ECC?

Thanks in advance.

Michel