icenowy:

Currently in ath79 the partition table are all defined as fixed partition table in device tree, instead of detecting it dynamically in the kernel.

This makes hardware modding not possible except with the firmware patched (which means that the firmware will thus receive no official support from OpenWRT).

In ar71xx, at least for TP-Link devices, we use some auto-detecting partition table driver to decide the partition table, and usually it can well suite modded hardware.