initramfs起根文件系统出错

已经先做好了文件系统，编译内核后的信息是这样的：
Image Name:   Linux-2.6.30.4-EmbedSky
Created:      Sat Apr 30 22:15:25 2011
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    3179548 Bytes = 3105.03 kB = 3.03 MB
Load Address: 0x30008000
Entry Point:  0x30008000
  Image arch/arm/boot/uImage is ready

通过tftp下载到内存中，系统起不来
最后停下位置如下：
  #0: S3C24XX_UDA134X (UDA134X)
TCP cubic registered
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
lib80211: common routines for IEEE802.11 drivers
s3c2410-rtc s3c2410-rtc: setting system clock to 2011-04-30 22:41:02 UTC (1304203262)
VFS: Cannot open root device "mtdblock2" or unknown-block(31,2)
Please append a correct "root=" boot option; here are the available partitions:
1f00             256 mtdblock0 (driver?)
1f01            3072 mtdblock1 (driver?)
1f02          257024 mtdblock2 (driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,2)
Backtrace:
[<c0133e5c>] (dump_backtrace+0x0/0x114) from [<c03ff350>] (dump_stack+0x18/0x1c)
r7:00008000 r6:c380c000 r5:c011883c r4:c056dfc0
[<c03ff338>] (dump_stack+0x0/0x1c) from [<c03ff3a0>] (panic+0x4c/0x114)
[<c03ff354>] (panic+0x0/0x114) from [<c0008f3c>] (mount_block_root+0x1e0/0x220)
r3:00000000 r2:20000013 r1:c381df60 r0:c04cadad
[<c0008d5c>] (mount_block_root+0x0/0x220) from [<c0009040>] (mount_root+0xc4/0xfc)
r8:00000000 r7:00000000 r6:00000000 r5:c011883c r4:01f00002
[<c0008f7c>] (mount_root+0x0/0xfc) from [<c00091e8>] (prepare_namespace+0x170/0x1c8)
r5:c011883c r4:c056d984
[<c0009078>] (prepare_namespace+0x0/0x1c8) from [<c0008474>] (kernel_init+0xbc/0xe8)
r5:00000000 r4:c056d960
[<c00083b8>] (kernel_init+0x0/0xe8) from [<c0144120>] (do_exit+0x0/0x58c)
r5:00000000 r4:00000000

求各位大神帮帮忙！