after a long time learning and code checking, several things has been done:

1)kconfig language have already been learned,  i learned all of these things from “http://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt”

2)much clear with libpayload xcompile code and menuconfig things. i reviewed all of the code under libpayload/util.

question is i do not know what interface should be added into the libpayload menuconfig. and i also have an doubt about the coreboot xcompile. why not just put the files into the trunk but instead of making the downloaded with and script?