U-Boot FAQ

How do I use U-Boot to store binaries in FLASH ?

A: One U-Boot available on the board, you can use it to flash binaries on storage media. The following examples can be used for Linux kernel, root filesystem or whatever you binary you want on your FLASH storage media :

• Use U-Boot to write JFFS2 in NAND FLASH => use of the nand write command
• Use U-Boot to write JFFS2 in NOR FLASH => use of the cp.b command applicable for DataFlash and any binary file

How do I access U-Boot environment while Linux is running ?

A: U-Boot provides little command line tool to access environment from Linux. It is located in U-Boot source code tree : tools/env directory. You will certainly have to tailor your MTD partitioning to identify the U-Boot environment in one MTD partition.
Have a look at the U-Boot README documentation for fw_env.

Here is a post in at91.com forum that talks about modifying U-Boot parameter out of Linux.