[U-Boot] question about TEXT_BASE in U-boot

Hi everyone:

I am a freshman in U-boot development. My question to all expert is:

I set TEXT_BASE=0xA0f00000 in board/LPC2468OEM_Board/config.mk.

After compile, the first instruction is: a0f00000: ea000014 b a0f00058 <reset>

However there is nothing at a0f00058 after power up board, so that system hang up. (I download u-boot to ROM flash)

Can anyone explain that how u-boot boot after power up and what shall I do to make u-boot work right?

Thanks very much.