[U-Boot-Users] How to make printf work?

Hi friends:

I am using u-boot.1.1.3 on my mpc8540 board now.When the u-boot code is running,printf() can not output any infomation even a single charactor,but puts() can.If printf() is not used,the monitor prompt "=>" is ok.I think both DDR and LBC are working well,maybe there is something wrong with the init_ram(cache)?

Regards, zhangwk