U-Boot is the booloader for the CORE9X35 board.
How to compile u_boot:
Install the cross compiler and the toolchain required on your Linux Ubuntu PC following this article (Tested on Ubuntu 12.04):
Copy the CORE9G25 u-boot-at91-master.tar.bz2 to the PC /tmp folder(You can download it from here), then do the follow command to uncompress it:
~$ cd ~ ~$ tar xvf /tmp/u-boot-at91-master.tar.bz2 -C .
This is a fork of the original Atmel version available on GitHub.
Move inside the at91bootstrap directory and launch Make:
~$ cd u-boot-at91-master/ ~/u-boot-at91-master$ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- distclean ~/u-boot-at91-master$ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- at91sam9x5ek_nandflash_config
If you use the 256MB DDR2 RAM version, run the follow command instead the above command:
~/u-boot-at91-master$ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- at91sam9x5ek_nandflash_256M_config
When the configuration in ready save and launch the compilation by typing:
~/u-boot-at91-master$ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- -j4 at91sam9x5ek_nandflash
Copy the binary file u-boot.bin to USB Disk, and then you can insert it to the board to update the bootstrap file(refer to the Update the system image by USB Disk)
~/u-boot-at91-master$ cp u-boot.bin /media/usbhd-sda1/
/media/usbhd-sda1/ is the USB Disk
