shell$ git clone --depth=1 -b v2017.11-1 https://github.com/ikwzm/FPGA-SoC-U-Boot-DE10-Nano.git
Pleade refer to the Readme.md of https://github.com/ikwzm/FPGA-SoC-U-Boot-DE10-Nano
shell$ cd FPGA-SoC-U-Boot-DE10-Nano
shell$ install -d ../target/de10-nano/u-boot/
shell$ cp u-boot-spl.sfp ../target/de10-nano/u-boot/u-boot-spl.sfp
shell$ cp u-boot.img ../target/de10-nano/u-boot/u-boot.img