Got a little side-tracked with udoo quad but now arduino IDE works in a gentoo rootfs with mainline everything. The graphics are about the same as nitrogen6x/cubox using FOSS drivers with xorg/mesa/dri3. Neo needs more DTS ports from 4.1 but works over usb serial/ethernet and wifi. Hopefully I should have some holiday time to look at Neo M4 stuff. My configs for core-image and your command line image are here: https://github.com/sarnold/meta-small-arm-extra/tree/morty/conf
Got a little side-tracked with udoo quad but now arduino IDE works in a gentoo rootfs with mainline everything. The graphics are about the same as nitrogen6x/cubox using FOSS drivers with xorg/mesa/dri3. Neo needs more DTS ports from 4.1 but works over usb serial/ethernet and wifi. Hopefully I should have some holiday time to look at Neo M4 stuff. My configs for core-image and your command line image are here: https://github.com/sarnold/meta-small-arm-extra/tree/morty/conf