u-boot and ramdisk

I have some problems when I boot.


It is console messages :

RAMDISK: Compressed image found at block 0
RAMDISK: incomplete write (-28 != 32768) 0
EXT3-fs: unable to read superblock
EXT2-fs: unable to read superblock
FAT: unable to read boot sector
VFS: Cannot open root device "ram" or unknown-block(1,0)
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)

after google,

I know what happened.I forgot to set ram disk size. After use

setenv ramdisksize 96000

It works well.