I am preparing to experiment with U-boot for Raspberry pi. For that reason I did some research about the boot process. What I understand is that the first stage boot loader is hard coded in the Broadcomm SoC's ROM, which in turn bootstraps the second stage boot loader from the SD card. Then the third stage boot loader boots which finally wakes up the CPU.
I get very confused about the stage of U-boot, will it replace second stage boot loader? Or simply it will executed only after all the previously mentioned ones are done?