Build Uboot
Installing the build tools and download source
Please follow linux user guide to install the build tools and download source.
Compile the Uboot
You should choose your board defconfig from here. ie. we are using evb-rk3288.
CROSS_COMPILE=arm-linux-gnueabihf- make evb-rk3288_defconfig all
Others
Now you can get u-boot SPL and u-boot image, but please notices that in some platform or station（like secure-os)， we will not use the u-boot SPL.
There are two feasible way to boot to u-boot.
1. RK SPL bin(DDR.bin, miniloader)
2. official u-boot SPL
The following wiki is writed for using u-boot SPL. If you are using a miniloader, you might need modify the steps.