Zephyr-Bazel

The way this repository works is by overlaying itself on top of Zephyr. To get started, first make sure you have Bazel‘s skylib version 1.7.1 or greater. If you don’t have it, you can use:

http_archive(
    name = "bazel_skylib",
    sha256 = "bc283cdfcd526a52c3201279cda4bc298652efa898b10b4db0837dc51652756f",
    urls = [
        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.7.1/bazel-skylib-1.7.1.tar.gz",
        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.7.1/bazel-skylib-1.7.1.tar.gz",
    ],
)

load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")

bazel_skylib_workspace()

Usage in WORKSPACE

To grab the zephyr-bazel repo, use a git_repository rule in your WORKSPACE, such as:

git_repository(
    name = "zephyr-bazel",
    remote = "https://pigweed.googlesource.com/zephyr/zephyr-bazel",
    branch = "main",
)

Once you have @zephyr-bazel, we can load the patch rule to generate the Zephyr diff that will augment Zephyr to include the BUILD.zephyr rules.

load("@zephyr-bazel//:setup.bzl", "create_zephyr_patch_file")

create_zephyr_patch_file(
    name = "zephyr-patch",
    filename = "patch.diff",
    # This is optional, use it to see what's going on under the hood
    debug = True,
)

We now have a diff file at @zephyr-patch//:patch.diff. We're ready to load Zephyr.

git_repository(
    name = "zephyr",
    remote = "https://github.com/zephyrproject-rtos/zephyr.git",
    branch = "main",
    patches = [
        "@zephyr-patch//:patch.diff",
    ],
)

The final step will be to load Zephyr's python dependencies:

load("@rules_python//python:pip.bzl", "pip_parse")

pip_parse(
    name = "py_deps",
    python_interpreter_target = interpreter,
    requirements_lock = "@@zephyr//:scripts/requirements-base.txt",
)

load("@py_deps//:requirements.bzl", zephyr_install_deps = "install_deps")

zephyr_install_deps()

Usage in bzlmod

To use zephyr-bazel in bzlmod, first add it as a dependency in your project's MODULE.bazel:

bazel_dep(name = "zephyr-bazel")
git_override(
    module_name = "zephyr-bazel",
    remote = "https://pigweed.googlesource.com/zephyr/zephyr-bazel",
    branch = "main",
)

Then use the zephyr_patch_file module extension to generate a patch file and a Bazel repo with the patch file applied:

zephyr_patch_file = use_extension("@zephyr-bazel//:setup.bzl", "zephyr_patch_file")
use_repo(zephyr_patch_file, "zephyr")

pip is required by the patched zephyr repo, so your project needs to inject it:

pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
# Load the Zephyr pip requirements
pip.parse(
    hub_name = "pip",
    python_version = "3.11",
    requirements_lock = "@zephyr//:scripts/requirements-base.txt",
)
use_repo(pip, "pip")

inject_repo(zephyr_patch_file, "pip")

Application

In your main application, you can now use the Zephyr utilities for building your app.

load("@zephyr//:defs.bzl", "dts_cc_library")

dts_cc_library(
    name = "app_native_sim_dts",
    dts_lib = "@zephyr//boards/native/native_sim:native_sim",
)

cc_binary(
    ...
    deps = [
        ...
        "@zephyr//:zephyr",
    ] + select({
        "@platform//cpu:x86_64": [
            ":app_native_sim_dts",
            "@zephyr//include:posix",
        ],
    }),
    copts = select({
        "@platform//cpu:x86_64": [
            "-DCONFIG_ARCH_POSIX=1",
        ],
    }),
)

Examples

Examples are located in the examples/ directory, which contains its own MODULE.bazel. Each subdirectory is a different example project.

To build all of the examples, run the following:

cd examples
./pw default

To build, individual examples specify the target platform. For example:

bazelisk build //hello_bazel --platforms=//hello_bazel:robokit1
bazelisk build //nrf52 --platforms=//nrf52:nrf52833dk

See the "builds" in examples/workflows.json for an up-to-date list of commands for building examples.