Zephyr images can run on various hardware platforms. Some of these do not have native yocto/oe-core support. In order to support platforms with Intel IAMCU (for example Arduino 101), we need the corresponding toolchain.
There is support for IAMCU in Zephyr SDK, so it should be straightforward to re-use the recipes.
I have succeeded to cross-compile the sample "philosophers" with IAMCU toolchain and flash the image on Arduino 101 board. $ MACHINE=arduino-101 bitbake zephyr-philosophers
merged meta-zephyr: https://git.yoctoproject.org/cgit/cgit.cgi/meta-zephyr/commit/?id=895c53de142e1311d52a4de3552ee81bbe5e1ab8