U-Boot/Legacy U-Boot

Initially u-boot sunxi port developed by Tom Cubie. Now within sunxi community developed and maintained by Henrik Nordström the u-boot support comes in two branches, one with NAND and android stuff(boot.img, fastboot) support and another with MMC-only ( aka SD ) support, which is more the traditional linux style.

For details see the linux-sunxi u-boot wiki.

Compilation
First of all you need a suitable toolchain installed and added to your PATH. Then proceed as follows.

git clone https://github.com/linux-sunxi/u-boot-sunxi.git
 * Clone sunxi version of u-boot git repository:


 * Go to the project directory and execute the build commands. Replace the board name in the third command with the one you are working with. Cubieboard is used in this example. The full list of supported boards is included in the 'u-boot-sunxi/boards.cfg' file you just cloned.

cd u-boot-sunxi make distclean CROSS_COMPILE=arm-linux-gnueabihf- make Cubieboard CROSS_COMPILE=arm-linux-gnueabihf-

Here, "CROSS_COMPILE=arm-linux-gnueabihf-" is the architecture designation which should match your toolchain and "Cubieboard" should be replaced by your board model. See the boards.cfg file for possible board configuration variants.

make Cubieboard CROSS_COMPILE=arm-linux-gnueabihf- is shorthand for make Cubiebaord_config CROSS_COMPILE=arm-linux-gnueabihf- make CROSS_COMPILE=arm-linux-gnueabihf-


 * After finishing you'll find the following compiled files, required for booting:

spl/u-boot-spl.bin u-boot.bin

u-boot nand environment
Example u-boot environment from a stock android u-boot environment partition

bootdelay=0 bootcmd=run setargs boot_normal console=ttyS0,115200 nand_root=/dev/nandc mmc_root=/dev/mmcblk0p4 init=/init loglevel=8 setargs=setenv bootargs console=${console} root=${nand_root} init=${init} loglevel=${loglevel} boot_normal=nand read 40007800 boot;boota 40007800 boot_recovery=nand read 40007800 recovery;boota 40007800 boot_fastboot=fastboot

set u-boot environment variable
For setting environment variable in uboot interactive shell, you must not place the '=' sign between variable name and value you want to asign.

setenv root /dev/sda1

But, iff you display environment variable in uboot interactive shell, you will see a '='

root=/dev/sda1

mmc environment
If you do this on an already existing SD-card image you may also want to clear the u-boot environment area, to remove any old settings that may have been saved there and return to the (very reasonable) u-boot defaults:

dd if=/dev/zero of=/dev/sdX bs=1024 seek=544 count=128