For systems with multiple paths to the network, different situations
may call for different paths to be used. Therefore, allow the user to
override the active interface via the environment on the auxiliary
partition.
The default (defined the bootloader's device tree) is still used in
cases when nothing else is specified in the environment.
Generate a boot menu, accessible with C-c during a short window, where
a user can interactively select a custom boot source and/or trigger a
factory reset of the device.
With this in place, we should always be able to unbrick a device, as
the image can be fed over the network, and local data can be ignored
by opting in to a factory reset.
Tobias Waldekranz