求助：ramdisk文件系统

xbzthb

我的系统启动信息如下：
Starting kernel ...

Uncompressing Linux............................................................................... done, booting the kernel.
Linux version 2.6.10_mvl401-ixdp42x-arm_xscale_be (root@localhost.localdomain) (gcc version 3.3.2) #796 Wed Mar 25 17:23:04 CST 2009
CPU: ARM920Tid(wb) [41129200] revision 0 (ARMv4T)
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
Machine: SMDK2410
Memory policy: ECC disabled, Data cache writeback
CPU S3C2410A (id 0x32410002)
S3C2410: core 202.800 MHz, memory 101.400 MHz, peripheral 50.700 MHz
S3C2410 Clock control, (c) 2004 Simtec Electronics
Built 1 zonelists
Kernel command line: initrd=0x30800000,0x400000 root=/dev/ram0 init=/linuxrc netmac=00:cf:0a:be:04:25 ip=172.18.104.123 console=ttySAC0,115200 mem=128M
irq: clearing subpending status 00000002
PID hash table entries: 1024 (order: 10, 16384 bytes)
timer tcon=00500000, tcnt a509, tcfg 00000200,00000000, usec 00001e4c
Console: colour dummy device 80x30
Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
Memory: 128MB = 128MB total
Memory: 123136KB available (2012K code, 431K data, 92K init)
Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
spawn_desched_task(00000000)
desched cpu_callback 3/00000000
ksoftirqd started up.
softirq RT prio: 24.
desched cpu_callback 2/00000000
checking if image is initramfs...it isn't (no cpio magic); looks like an initrd
desched thread 0 started up.
Freeing initrd memory: 4096K
NET: Registered protocol family 16
S3C2410: Initialising architecture
S3C2410 DMA Driver, (c) 2003-2004 Simtec Electronics
DMA channel 0 at c8800000, irq 33
DMA channel 1 at c8800040, irq 34
DMA channel 2 at c8800080, irq 35
DMA channel 3 at c88000c0, irq 36
NetWinder Floating Point Emulator V0.97 (extended precision)
devfs: 2004-01-31 Richard Gooch (rgooch@atnf.csiro.au)
devfs: devfs_debug: 0x0
devfs: boot_options: 0x1
Installing knfsd (copyright (C) 1996 okir@monad.swb.de).
S3C2410 RTC, (c) 2004 Simtec Electronics
S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics
s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2410
s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2410
s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2410
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered
RAMDISK driver initialized: 1 RAM disks of 16384K size 1024 blocksize
loop: loaded (max 8 devices)
elevator: using anticipatory as default io scheduler
nbd: registered device at major 43
dm9000_init
dm9000:phy addr=0x8000300 -> virt addr=0xc8810300
<DM9000> I/O: c8810300, VID: 90000a46
dm9000 found
eth0: at 0xc8810300 IRQ 16
eth0: Ethernet addr: 00:cf:0a:be:04:25
mice: PS/2 mouse device common for all mice
NET: Registered protocol family 2
IP: routing cache hash table of 1024 buckets, 8Kbytes
TCP: Hash tables configured (established 8192 bind 16384)
NET: Registered protocol family 1
RAMDISK: Compressed image found at block 0
VFS: Mounted root (ext2 filesystem).
Mounted devfs on /dev
Freeing init memory: 92K

ramdisk文件大小为3.3M，在内核中指定ramdisk大小为16M，这个文件系统在PXA270的板子上跑没有问题。
如果使用另一个类似大小的文件系统（未在其他板子上试过），会多出下面这一行信息
Kernel panic - not syncing: No init found.  Try passing init= option to kernel.
但用一个以前在2.4内核下跑的文件系统没有问题（ramdisk文件大小为1.9M，busybox版本较低）
我被这个问题捆扰了好久，到底是u-boot的问题还是内核或者是文件系统制作的问题，请哪位指点一下？？？？