[U-Boot] u-boot didn't mount ramdisk ...

[mike xu]

Hi All,

I am using u-boot 1.2.0 and tried to boot kernel with one ramdisk, but
it seems the u-boot doesn't load my ramdisk image at all. Please view
the below log message for detailed informations.

=> tftpboot a0800000 uRamdisk
=> iminfo a0800000
## Checking Image at a0800000 ...
   Image Name:   Test Ramdisk Image
   Created:      2008-12-17  11:43:47 UTC
   Image Type:   MIPS Linux RAMDisk Image (gzip compressed)
   Data Size:    3824687 Bytes =  3.6 MB
   Load Address: 82010000
   Entry Point:  82010000
   Verifying Checksum ... OK
=> bootm bfc60000 a0800000
## Booting image at bfc60000 ...
   Image Name:   MIPS OpenWrt Linux-2.6.21.7
   Created:      2008-12-16  19:55:08 UTC
   Image Type:   MIPS Linux Kernel Image (gzip compressed)
   Data Size:    1172251 Bytes =  1.1 MB
   Load Address: 80010000
   Entry Point:  80262000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
## Loading Ramdisk Image at a0800000 ...
   Image Name:   Test Ramdisk Image
   Created:      2008-12-17  11:21:06 UTC
   Image Type:   MIPS Linux RAMDisk Image (gzip compressed)
   Data Size:    3824687 Bytes =  3.6 MB
   Load Address: 82010000
   Entry Point:  82010000
   Verifying Checksum ... OK
/* COMMENT ADDED BY MIKE, boot loader hasn't loaded RAMDISK since no
"Loading Ramdisk to..." output...... */

Starting kernel ...

LINUX started...
...
No filesystem could mount root, tried:  cramfs squashfs romfs
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)


Are there any special requirement of the ramdisk format for u-boot? I
used mips mkimage command as below and both of the ramdisk.gz in ext2
or cramfs format are all failed.
mkimage -O linux -A mips  -T ramdisk -C gzip -n 'Test Ramdisk Image'
-d ramdisk.gz uRamdisk

Could somebody give me any suggestions?

Thanks,
Mike