Android Customizing U-Boot

Manual operations

Build boot.img

When you perform changes to the kernel, you may build boot.img solely instead of building the whole Android.

$ cd / 
$ source build/envsetup.sh
$ lunch var_mx6-eng
or
$ lunch var_mx6-user
$ make bootimage

Toolchain setup for manual U-Boot build

$ export ARCH=arm
Setup the toolchain path to point to arm-eabi- tools in prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/bin
$ export CROSS_COMPILE=//prebuilts/gcc/linux-x86/arm/arm-eabi-4.8/bin/arm-eabi-

Manual build Bootloader 

Change directory to U-Boot

$ cd //bootable/bootloader/uboot-imx

Execute following commands:

clean tree:
$ make mrproper

Choose build for SD card or NAND flash:
$ make mx6var_som_sd_android_defconfig
or
$ make mx6var_som_nand_android_defconfig

Build U-Boot:
$ make -j4

This command will generate the U-Boot images 'SPL' and 'u-boot.img'.