It may come as a surprise to you, but network boot is a pretty generic feature, which had been around long before the Raspberry Pi boards came to existence.stderr wrote:Net boot is huge for anyone looking to build with these things in a low cost manner and as far as I know only the pi people are paying attention so far to this point.
Still without a bootable SD card, Orange Pi boards can only boot over USB because that's what is supported by the on-chip boot ROM. Booting over Ethernet requires a bootloader, which itself can be loaded from a (small and cheap) SD card or over USB. Please note that the mainline U-Boot does not support Ethernet on Allwinner H3 boards yet and this feature may take a bit of time to become fully supported. As a side note, the mainline U-Boot supports Ethernet on older Allwinner chips perfectly fine and is fully network boot capable.
As for booting over USB on Orange Pi PC or Orange Pi One boards, this feature is for example utilized for doing a RAM reliability test: https://linux-sunxi.org/Orange_Pi_PC#DR ... peed_limit
This is convenient because people don't need to use a spare SD card for doing this test and also they don't need to repeatedly move the SD card between the board and a card reader to modify the DRAM clock speed settings.