Thanks @kwankiu 
I’m trying to achieve netbooting on my 5C lite (with a PoE hat).
The idea is to have a U-boot running on the SPI flash module handling OS files from a TFTP & NFS server.
I’ve already done that with Rpi devices.
Unfortunately, no matter the way I tried, I can’t make my board boot.
- rsetup tells me it succeed -> no output when powering on and fixed green and blue LEDs
- dding idbloader + u-boot.itb on a GPT manually created image (https://wiki.radxa.com/Rock3/install/spi#Create_GPT_U-Boot_image) -> only green light and no output
- rkdeveloptool + https://dl.radxa.com/rock5/5c/images/loader/spi/ -> same result as rsetup
The only one which gave me output and blinking blue LED is EDK2-porting firmware, however it seems that netboot options are only provided on REALTEK NIC equipped devices. (https://github.com/edk2-porting/edk2-rk3588/issues/181)
UPDATE
