These methods don’t work (not anymore!? or at least not with all versions or combinations).
Is it possible to share an ADB executable built with Linaro 12.12 so that I can test it without rebuilding from source?
There is no reason for having adb being built from source.Most of us use the prebuilt adb and works fine for us. Even LAVA uses a prebuilt adb and it works fine with other RTSM.
Can you make sure networking is working fine on the RTSM. Then restart adb on the target:
stop adbd
setprop service.adb.tcp.port 5555
start adbd
and then connect from the host (assuming you have user mode networking):