[U-Boot] Booting PowerPc

Hi, I'am new with PowerPc and try to boot the MPC8315ERDB board with u-boot (1.3.3). All standard images build from the linux powerpc arch won't work. I see in the uImage there is a kernel image and a initrd image.

At the moment I build the image by hand with mkimage including kernel, initrd and dtb.

Could someone give me the standard way to boot?

Günter