Hello
I'm trying to migrate an existing MPC8540 based system's 2.4 kernel to 2.6.15.1 kernel. I have made configuration changes accordingly and got the kernel image. Please find attached the .config file.
Also, made changes to rc.sysinit, fstab, halt etc to support sys file system and other 2.6 related changes. I have updated busybox binary image to busybox-1.6.0. Now when i use the rootfs.gz image along with kernel image and try to boot from memory using UBoot for the target system I get:

## Booting image at 00200000 ...
Image Name: Linux-2.6.15.1
Image Type: PowerPC Linux Kernel Image (gzip compressed)
Data Size: 1298592 Bytes = 1.2 MB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
## Loading RAMDisk Image at 00a00000 ...
Image Name: RAM disk
Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
Data Size: 8628956 Bytes = 8.2 MB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
Loading Ramdisk to 3f763000, end 3ff9dadc ... OK

and it just hangs there. When i try to use only kernel image i get the error:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)

I'm new to this. Please help.
Thanks