We provided Fenix for you to build the Ubuntu OS images easily.
You can follow the steps below to build the Ubuntu OS image.

Choose your board (e.g. VIM4), U-Boot version, Linux version, system version, etc.

source setenv.sh

Choose the correct version for your requirements.

Build U-Boot with a single command:

make uboot

The binaries are located in `build/u-boot/fip/_tmp`. You'll need `u-boot.bin.sd.bin.signed`, ` u-boot.bin.signed`, and `u-boot.bin.spi.bin.signed`.

• u-boot.bin.sd.bin.signed - for burning to the SD card
• u-boot.bin.signed - for burning to the eMMC
• u-boot.bin.spi.bin.signed - for burning to the SPI Flash

You can also choose the Debian U-Boot package:

make uboot-deb

Debian packages are located in build/images/debs/{VERSION}/{BOARD}.

VERSION : refers to the Fenix version, e.g. `1.0.7` BOARD : refers to the Khadas SBC, e.g. `VIM4`

The folder location is `build/images/debs/1.0.7/VIM4`, and the Debian U-Boot package is `linux-u-boot-xxx-xxx_xxx-xxx_arm64.deb`.

• SoC Vendor Debian U-Boot package: `linux-u-boot-vim4-vendor_1.0.7-2019.01_arm64.deb`