[U-Boot] Customize U-boot

[alfred steele]

Hi,
I am trying to modify uboot to use the available FAT32 APIs and the
mmc driver apis  in order to auto magically boot from a SD card if its
present in the slot of our board.
I know it can be done by statically defining EXTRA_ENVS in the board
config file and use the U-boot scripting framwork to do so.

But i do not intend to use just the scripts to acheive that. The
reason is we need to modify the config everytime the initramdisk and
kernel image size changes.

i  am trying to do it using U-boot api's available  like the way
U-boot api's are used in "common/update.c" to boot from mmc/sd only if
the card is available, otherwise boot from NAND.
Another question here is whether the flash_api like flash_write/
flash_erase only make sense for NOR flash. Are there any similar API's
available for the NAND subsystem.

Thanks in advance for your help.
-Alfred