In message BAY8-DAV46wN9X9DsvO0000fc0c@hotmail.com you wrote:

I am a newer about u-boot,and now I am trying to read the sourcecodes of

u-boot. But it is difficult for me to understand it.So problems happens when i try to understand the program language,such as .text /.long /.global .now I can.t find the proper books or articles to study it ,maybe ,someone of you could give me some hint about how to understand the program language or some books and some useful matiarials.

You got to learn to use search engines. Simple searches like for example for "powerpc assembler language" return lots of quite useful stuff.

For a start, please see http://www.denx.de/twiki/bin/view/Training/MoreInformationMoreLinks

Best regards,

Wolfgang Denk