Problem: erase mtd device

[hking]

This is what I got after I added three custom partitions in the physmap.c:
After the kernel (2.4.20) boots up, I logged in as root and type:
#cat /proc/mtd
== and I got:
dev:    size   erasesize  name
mtd0: 00040000 00040000 "ResetWord"
mtd1: 01ec0000 00040000 "User FS"
mtd2: 00100000 00040000 "UBOOT"


The size, erasesize and name look correct.  It does not say the starting point 
of each partitions.  Since our first and third partition are write-protected, 
so I tried to erase the mtd1.


And I typed:
#erase /dev/mtd1
== and I got:
File open error


And I typed:
#eraseall /dev/mtd1
== and I got:
eraseall: /dev/mtd1: No such device


Did I do anything wrong?