[U-Boot] Fw:How can I use yaffs2 in uboot

How can I use yaffs2 in uboot

I add CONFIG_YAFFS2 in /include/configs/smdk2410.h

my2440 # nand write 0x30008000 80000 40000

NAND write: device 0 offset 0x80000, size 0x40000

262144 bytes written: OK

my2440 #

my2440 # ymount /flash

yaffs: Mounting /flash

my2440 # ywrm a 0x30008000 40000

Error opening file: -1

I also need what parameters ?

thanks!