[U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular
javierruere at apexar.com
Wed Jan 3 23:49:25 CET 2007
I have been working with an AT91RM9200-EK board for a couple of months now
and we are about to make our own custom board. Lately I started investigating
about U-Boot and how it works in this board and, though I have found a lot of
bits of information, I am still quite confused.
I would like to ask about U-Boot running from RAM. On the one hand, I have
seen links  and  that say that it should not be done but, on the other
hand, from the documentation from Atmel  I see it _is_ being run from RAM.
I have done this myself with u-boot 1.1.6 defining CONFIG_SKIP_LOWLEVEL_INIT
at the top of include/configs/at91rm9200dk.h, otherwise it wouldn't work. I
found out about this define here 
For what I gather from the instructions from Atmel, there is always a
bootloader before U-Boot, loading it from the dataflash, serial port or Flash
and this could explain why I must define CONFIG_SKIP_LOWLEVEL_INIT, so that
the hardware is not initialized twice.
Would it work to put an uncompressed image of U-Boot at the beginning of the
flash memory and let it initialize the board if I don't add the define I
Thank you all for your time and help.
More information about the U-Boot