why ubimkvol can't recognize /dev/ubi0?

[时正]

Hi all,
I wanna have a try of ubifs on nandsim, and do as what the ubifs wiki
tells me
(http://osl.sed.hu/wiki/ubifs/index.php/Download_the_source).

1. compile, install and boot the new kernel(2.6.23)
the configuration option for ubi and nandsim is default turned on as module.


2. make the mtd-utils to produce ubimkvol

3. create a ubi when I got the error
# modprobe nandsim
# modprobe ubi mtd=0
# ls /dev/ubi0 -l
crw-rw---- 1 root root 253, 0 2007-12-25 01:46 /dev/ubi0
# ls /sys/class/ubi -l
drwxr-xr-x 3 root root 0 2007-12-25 01:46 ubi0
-r--r--r-- 1 root root 4096 2007-12-25 01:49 version
# ubimkvol /dev/ubi0 -n 0 -N test -s 20MiB
libubi error: readdir failed on "/sys/class/ubi"
readdir: No such file or directory
ubimkvol error: "/dev/ubi0" is not an UBI device node

it's so strange about the readdir failure, because there is the ubi0
entry in sysfs.

did I miss any step, such as kernel configuration or mtd-tools installation?

Thanks a lot!

best wishes, shizheng