This is a version of u-boot, modified to support Fuchsia on the Khadas vim3
To build the vim3 bootloader for Fuchsia:
Prerequisites - arm and aarch64 toolchains. On Debian/Ubuntu systems, for example:
apt-get install gcc-arm-none-eabi gcc-aarch64-linux-gnu
Run the build script from repo root
./build_uboot_vim3_zircon.sh
You now have a build/u-boot.bin.unsigned that you can flash to a target using fastboot.