How to use the device tree for lite5200

Hello,

I want to boot PowerPC Linux 2.6.19 on my Icecube board but I didn't 
succeed yet to get lite5200.dts compiled and an appropriate image created:

   $ dtc -b0 lite5200.dts
   DTC: dts->dts  on file "lite5200.dts"
   ERROR: Missing /chosen node
   Input tree has errors

What is the procedure to make and boot an uImage for the U-Boot 
bootloader. I read about the third argument for bootm but did not 
understand how to use it.

TIA.

Wolfgang.