RPI4 netboot support

[matthewbauer]

RPI4 netboot support

[euank]

I gave this a try, but I couldn't get it to work.

I flashed my eeprom to pieeprom-2020-09-03.bin and configured it to network boot.
pixiecore sees dhcp requests and responds to them, but the raspberry pi pxe implementation never tries to make a pxe or tftp request. It eventually gives the cryptic "NETBOOT init failed" and gives up after a few retries.

What I ended up doing that worked for my case is slapping a UEFI implementation on my sdcard, booting that, and then using the uefi pxe implementation. In conjunction with #121, that worked fine!

Shoutout to this blog post for suggesting that alternative method: https://www.virtuallyghetto.com/2020/07/two-methods-to-network-boot-raspberry-pi-4.html

Anyway, I guess the short of it is I think there's an rpi-eeprom bug that gets in the way of trivially fixing this, even after adding arm64 support to the code.

[taemon1337]

I am actually trying to do the same so am very interested as well