Hi Shizheng,

Very interesting: I compared YAFFS on-disk data generated by YAFFS on an empty partition and after programming with MTD utility nandwrite. As you suggested by using nanddump.

The YAFFS created OOB (spare unit) looks like this:

00000800  ff ff 01 10 00 00 0c 01  00 10 01 00 00 80 00 00  |��..............|
00000810  00 00 3c 00 00 00 00 00  00 00 00 00 00 00 ff ff  |..<...........��|
00000820  ff ff ff ff ff ff ff ff  aa 56 67 f3 3c 3f ff ff  |���������Vg�<?��|
00000830  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |����������������|

The OOB content after programming with nandwrite looks like this:

00000800  ff ff 00 00 01 00 00 00  00 00 00 00 ff ff 00 00  |��..........��..|
00000810  30 00 00 00 05 00 00 00  05 00 00 00 ff ff ff ff  |0...........����|
00000820  ff ff ff ff ff ff ff ff  aa 9a a7 fc 0f 3f ff ff  |���������.��.?��|
00000830  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |����������������|0

As you mentioned, there is a off-by-two shift. How can I resolve this? By modifying the mkyaffs2image utility? Is it the same as here http://www.aleph1.co.uk/lurker/message/20070912.140012.12f2d093.en.html ?

Thank you very much,
Peter V.