Learning Uboot programming

Please suggest methods or sources how to start uboot programmin开发者_运维知识库g.

The best method, meaning the one that will give you the best final understanding and insight, is to get a board with a working U-boot configuration, a JTAG debugger for that board, the source code, and dig in. Get it working straight up, then change things and see what happens. It is a well-maintained project, but the fundamental complexity of bootloaders (and especially a generic bootloader) make learning it a hands on kind of thing.