We recommend to use the default rockchip arm-eabi- toolchain from android to build all the stuff for rock/pro/lite including u-boot, kernel, android.

Install the toolchain

Download ARM toolchain if you don't have Android 4.2.2/4.4.2 SDK on your host.

if your host is 64bit

   git clone -b kitkat-release --depth 1 https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6

Or

  download the zip file here http://dl.radxa.com/rock/source/x86_64_arm-eabi-4.6.zip

if your host is 32bit

   git clone -b jb-release --depth 1 https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6

Or

   download the zip file here http://dl.radxa.com/rock/source/x86_32_arm-eabi-4.6.zip

then edit your ~/.bashrc, and set environment variables, add the following line at the end of .bashrc

   export ARCH=arm
   export CROSS_COMPILE=`pwd`/arm-eabi-4.6/bin/arm-eabi-

of course you can use any toolchain if you are sure it works, or you will have to fix any error introduced by toolchain.

Rock/install toolchain