[ELDK] Initramfs

[yel_yahc]

Hello, 
I set CONFIG_INITRAMFS_SOURCE="/home/user/initramfs" and I recompile my
kernel, and I /arch/powerpc/boot I had my uImage with 3.4Mo (1,6Mo of
kernel + 1,8 rootfs) I put this uImage in my U-Boot but I had a kernel
panic     
        VFS: Cannot open root device "<NULL>" or unknown-block(2,0)
        Please append a correct "root=" boot option 
Do you hava any idea?
Perhaps I didn't build correctly my initramfs?
my rootfs is in /home/user/initramfs and my kernel in
/home/user/ELDK/ppc_6xx/usr/src/linux 

Best regards