build: Collect syscall client files from modules In Zephyr's CMake build system, a CMake function zephyr_syscall_headers() is used in subdirectories to collect header files that use syscalls. The list of these header files (let's call them "syscall client files") is then processed by a Python script to generate the required syscall headers. This change introduces the Bazel equivalent of this mechanism. Filegroup targets are used to allow subdirectory BUILD.bazel files to declare syscall client files, in the same hierarchy as the zephyr_syscall_headers() calls in CMakeLists.txt. This opens the path to using a script to convert CMakeLists.txt to BUILD.bazel for every subdirectory, as the script only needs to convert each zephyr_syscall_headers() call to a filegroup. In the top-level BUILD.bazel, a zephyr_syscall_files() rule collects the final list of client files and completes the syscall header generation. Change-Id: I950c6a83a84f1d5263c5ac0ce4598244757c628f Reviewed-on: https://pigweed-review.googlesource.com/c/zephyr/zephyr-bazel/+/347253 Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com> Reviewed-by: Tim Knodel <tbk@google.com> Commit-Queue: Yicheng Li <yichengli@google.com>
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()
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()
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")
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",
],
}),
)
There is currently just 1 example, you can run it via:
$ cd examples/hello_dts $ bazel run :app
Or, you can run the tests via:
$ cd examples/hello_dts $ bazel test //...