after compilation of uboot i tried to load it to memory without success (~4.8mb).
using rkdeveloptool db rk3308_loader_uart0_m0_emmc_port_support_sd_20190717.bin before loading using gdb leads to, at least, successfull load.
maybe upstream evb-rk3308_defconfig is not the best choice.
nice to have / todo:
- tcl script for loading binary for ddr config
or - script which will do same instead