u-boot 32-bit on Raspberry Pi 4

Has anyone successfully used u-boot on the Raspberry Pi 4 in 32-bit mode?

Building via the following:

make rpi_4_32b_defconfig ARCH=arm CROSS_COMPILE=arm-none-eabi- make

Booting via:

* u-boot.bin on Fat32 partition * start.elf from * config.txt on Fat32 partition kernel=u-boot.bin enable_uart=1 arm_64bit=0

Just a black screen, however, no serial uart output

Thanks!

-- Alex