Chromium OS EC uses the zmake tool to build Zephyr.
This section describes how to build and use zmake.
Follow the Chromium OS Developer Guide to sync the source and get the chroot setup.
It is also possible to build without a Chromium OS chroot, albeit with additional setup steps. See out-of-chroot building if this interests you.
The Legacy EC required only a single repository, and thus, it was common for developers to sync just the EC repository using repo sync ..
Since the Zephyr build relies on multiple repositories, doing so will likely end you up in a broken state. Please be sure to do a complete sync when updating the source.
To build the EC for a single project, run:
(chroot) $ zmake build "${PROJECT}"
For example, to build the EC for skyrim, run:
(chroot) $ zmake build skyrim
The output binary will then be located at build/zephyr/skyrim/output/ec.bin.
Additional output files you may find useful:
build/zephyr/skyrim/output/zephyr.ro.elf - read-only ELF for debuggingbuild/zephyr/skyrim/output/zephyr.rw.elf - read-write ELF for debuggingYou might also find these files useful (using read-only as an example):
build/zephyr/skyrim/build-ro/zephyr/.config - Kconfig options selectedbuild/zephyr/skyrim/build-ro/zephyr/include/generated/devicetree_unfixed.h - the (large) header file that zephyr uses to provide devicetree information to the C codebuild/zephyr/skyrim/build-ro/zephyr/zephyr.dts - devicetree that is usedbuild/zephyr/skyrim/build-ro/zephyr/zephyr.dts - map of imageFor a complete list of zmake commands and options, see the Zmake Documentation.
Googlers may be interested in setting up building with Goma as well.
There is also a an ebuild for integration into the larger Chromium OS build system.
To build using this flow, run:
(chroot) $ emerge-${BOARD} chromeos-base/chromeos-zephyr
It should be possible to do this with:
ninja -C /tmp/z/volteer/build-ro menuconfig
However at present this does not work b/184662866.