Configurable IP address in build

At present openwrt uses as default IP address. This address is set using config_generate file found in base-files folder.
I want to implement a feature where a developer can specify the default IP Address in the arch make file itself. E.g. there are 2 boards Board 1 and Board 2 using mt7621. The image building is specified in I would like to add a configuration e.g. DEFAULT_IP_ADDRESS:= for Board 1 and DEFAULT_IP_ADDRESS:= for Board 2. I am not able to find how can we achieve this? Any pointers in this regard will be very useful.
Thanks in advance.

While you can certainly hack that in (e.g. via uci-defaults), there is no 'official' provision for this - and in cases like that it rarely stops at just the IP address, but will need further customizations anyways.