[U-Boot] [U-Boot-Users]-boot monitor function

Hi.... i am new to u-boot and my board supported a boot monitor. what this boot monitor does for the board. i read in this link http://blogs.coreboot.org/blog/2011/06/05/gsoc2011week-1-analysis-of-u-boot-... board has its own boot monitor running before U-boot and init the RAM for us. So we have nothing to do in the function lowlevel_init. so like this what are all the function we can avoided if the board supports own boot monitor. whether it does POST operation? if so can i avoid post directory in u-boot?