How to compile my own u-boot

Hi,

How can I compile my own u-boot? I want to do this because memory available is low, I want to make this changes by myself:
http://www.udoo.org/forum/viewtopic.php?f=2&t=120&start=30#p1378

Kernel is already compiler using 32M GPU.

 

You can use more memory without recompilinf kernel or uboot:

Stop boot process by serial console hiting enter button, and then change bootargs string changing this parameter:

mem=768M

whit this:

mem=1024M

Let me know your result!

 

it works, thanks.