Clone the branch pocketgo-s30 of our fork of the linux repo:

$ git clone -b pocketgo-s30 https://github.com/PocketGo-S30-CFW/linux.git
$ cd u-boot
$ make sunxi_defconfig
$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j17

Note: change the -j17 to your number of cores+1 (e.g. 8 cores -> -j9)