U-Boot for RK3288 doesn't have PSCI implemented, so ATF is required to use virtualization on RK3288.
make ARCH=aarch32 CROSS_COMPILE=arm-linux-gnueabihf- PLAT=rk3288 AARCH32_SP=sp_min
cp ~/arm-trusted-firmware/build/rk3288/release/bl32/bl32.elf ./bl31.elf
pip3 install pyelftools
tools/mkimage -n rk3288 -T rksd -d tpl/u-boot-tpl.bin idbloader.img
cat spl/u-boot-spl.bin >> idbloader.img
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- evb-rk3288-rk808_defconfig