To make your customized official uboot or our standard uboot, it requires two steps.

1. Download latest uboot source code from https://github.com/u-boot/u-boot/tags, normally I choose the stable version who is not end with rc.
2. Use our config file from https://github.com/Vonger/vocore2/blob/master/uboot/vocore2_defconfig, replace u-boot-2023.04/configs/vocore2_defconfig, then you can use make menuconfig to choose the option you want.

optional: for simple, after replace vocore2_defconfig, you can directly call make vocore2_defconfig, then call CROSS_COMPILE=mipsel-openwrt-linux- make, it will generate uboot by the default config.

PS: new version uboot compile size over 192KB, need to reduce…unselect Network Support it works. And customize uboot has some risk to brick your VoCore, better to have at least two VoCore or SPI flash loader to unbrick it if anything goes wrong. Check here vocore.io/v2.html, Unbrick VoCore2 part.