Hi @dgribben it seems that the openembedded devshell does not set DTC_FLAGS. It is available in the EXTRA_OEMAKE environment variable within the devshell but I couldn’t get make to function when called as make ${EXTRA_OEMAKE} dtbs. That resulted in a strange argument parsing error which probably had to do with shell globbing and such.
What did work for me was to simply invoke make DTC_FLAGS=-@ dtbs. This configures the DTBs to have device tree overlay compatibility.
Drew