kconfig.bzl - zephyr/zephyr-bazel - Git at Google

 # Copyright 2025 The Pigweed Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may not
 # use this file except in compliance with the License. You may obtain a copy of
 # the License at
 #
 #     https://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations under
 # the License.

 load("//bazel/private:repo_rule_python.bzl", "COMMON_PY_REPO_RULE_ATTRS", "get_python")

 _COMMON_KCONFIG_TREE_ATTRS = {
     "zephyr_root": attr.label(
         mandatory = True,
         allow_single_file = True,
     ),
     "board_name": attr.string(
         mandatory = True,
     ),
     "board_qualifiers": attr.string(),
 } | COMMON_PY_REPO_RULE_ATTRS

 _COMMON_CONF_FILE_ATTRS = {
     "conf_file": attr.label(
         mandatory = True,
         allow_single_file = True,
     ),
     "extra_conf_files": attr.label_list(),
 }

 def _construct_environment(repo_ctx):
     srctree = str(repo_ctx.path(repo_ctx.attr.zephyr_root).dirname)

     # Directories to hold outputs of kconfig_gen.
     kconfig_binary_dirname = "Kconfig"
     kconfig_board_dirname = "Kconfig/boards"
     # Zephyr 4.3 added an "env file" in the Kconfig tree. This is for post-build
     # metadata generation but is unconditionally sourced. We create an empty env
     # file here since we don't care about post-build metadata.
     kconfig_env_filename = "kconfig_module_dirs.env"
     repo_ctx.file(kconfig_env_filename)

     environment = {
         "srctree": srctree,
         "ZEPHYR_BASE": srctree,
         "KCONFIG_BINARY_DIR": str(repo_ctx.path(kconfig_binary_dirname)),
         "KCONFIG_BOARD_DIR": str(repo_ctx.path(kconfig_board_dirname)),
         "KCONFIG_ENV_FILE": str(repo_ctx.path(kconfig_env_filename)),
         "BOARD": repo_ctx.attr.board_name,
         "BOARD_QUALIFIERS": repo_ctx.attr.board_qualifiers,
         "ARCH_DIR": srctree + "/arch",
         "HWM_SCHEME": "v2",
     }
     return environment

 def _run_kconfig_gen(repo_ctx, python, environment):
     # Generate Kconfig snippets pointing to soc and arch directories.
     kconfig_gen_script_path = repo_ctx.path(Label("//scripts/build:kconfig_gen.py"))
     repo_ctx.watch(kconfig_gen_script_path)
     srctree = environment["srctree"]
     result = python.execute(
         [
             kconfig_gen_script_path,
             "--arch-root",
             srctree,
             "--soc-root",
             srctree,
         ],
         environment=environment,
     )
     if result.return_code != 0:
         fail("Failed to run kconfig_gen (%d):\n%s" % (result.return_code, result.stderr))

 def _write_configs_dot_c(repo_ctx, python, environment):
     # Generate configs.c
     # Only applies to project-specific configs repository.
     configs_c_filename = "generated/configs.c"
     repo_ctx.file(configs_c_filename)
     generate_configs_dot_c_script_path = repo_ctx.path(
         Label("//scripts/build:generate_configs_dot_c.py"))
     repo_ctx.watch(generate_configs_dot_c_script_path)
     args = [
         generate_configs_dot_c_script_path,
         "--autoconf",
         repo_ctx.path("generated/zephyr/autoconf.h"),
         "-o",
         repo_ctx.path(configs_c_filename),
     ]
     result = python.execute(
         args,
         environment=environment,
     )
     if result.return_code != 0:
         fail("Failed to generate configs.c from autoconf.h (%d):\n%s" % (result.return_code, result.stderr))

 def _write_build_file(repo_ctx):
     # Declare the autoconf cc library
     # Only applies to project-specific configs repository.
     repo_ctx.file(
         "BUILD.bazel",
         content=
 """package(default_visibility = ["//visibility:public"])

 cc_library(
     name = "autoconf",
     hdrs = ["generated/zephyr/autoconf.h"],
     includes = ["generated"],
 )

 filegroup(
     name = "configs_file",
     srcs = ["generated/configs.c"],
 )
 """,)

 def _gen_kconfiglib_impl(repo_ctx):
     environment = _construct_environment(repo_ctx)
     srctree = environment["srctree"]
     python = get_python(
         repo_ctx,
         extra_import_paths=[
             # Provide paths to kconfiglib and kconfigfunctions.py.
             srctree + "/scripts/kconfig",
         ],
     )
     _run_kconfig_gen(repo_ctx, python, environment)

     # Parse the Kconfig tree.
     build_file_name = "BUILD.bazel"
     build_file_path = repo_ctx.path(build_file_name)
     repo_ctx.file(build_file_name)
     bazel_config_script_path = repo_ctx.path(Label("//scripts/build:bazel_config.py"))
     repo_ctx.watch(bazel_config_script_path)
     args = [
         bazel_config_script_path,
         "--kconfig",
         srctree + "/Kconfig",
         "gen_kconfig",
         "-o",
         build_file_path,
     ]
     result = python.execute(
         args,
         environment=environment,
     )
     if result.return_code != 0:
         fail("Failed to generate kconfig BUILD file (%d):\n%s" % (result.return_code, result.stderr))

 gen_kconfiglib = repository_rule(
     implementation = _gen_kconfiglib_impl,
     attrs = _COMMON_KCONFIG_TREE_ATTRS,
 )

 def _gen_projectlib_impl(repo_ctx, python, environment):
     environment = _construct_environment(repo_ctx)
     srctree = environment["srctree"]
     python = get_python(
         repo_ctx,
         extra_import_paths=[
             # Provide paths to kconfiglib and kconfigfunctions.py.
             srctree + "/scripts/kconfig",
         ],
     )
     _run_kconfig_gen(repo_ctx, environment)

     # Parse the Kconfig tree.
     bazel_config_script_path = repo_ctx.path(Label("//scripts/build:bazel_config.py"))
     repo_ctx.watch(bazel_config_script_path)
     bzl_file_name = "kconfig_flag_values.bzl"
     bzl_file_path = repo_ctx.path(bzl_file_name)
     repo_ctx.file(bzl_file_name)
     args = [
         bazel_config_script_path,
         "--kconfig",
         srctree + "/Kconfig",
         "gen_project",
         "--project",
         str(repo_ctx.path(repo_ctx.attr.conf_file)),
         "-o",
         bzl_file_path,
         "--extra_configs_in",
     ]
     for config in repo_ctx.attr.extra_conf_files:
         args.append(repo_ctx.path(config))
     repo_ctx.file("generated/zephyr/autoconf.h")
     result = python.execute(
         args,
         environment=environment,
     )
     if result.return_code != 0:
         fail("Failed to generate kconfig BUILD file (%d):\n%s" % (result.return_code, result.stderr))

     _write_configs_dot_c(repo_ctx)
     _write_build_file(repo_ctx)

 gen_projectlib = repository_rule(
     implementation = _gen_projectlib_impl,
     attrs = _COMMON_KCONFIG_TREE_ATTRS | _COMMON_CONF_FILE_ATTRS,
 )

 def _kconfig_impl(module_ctx):
     if not module_ctx.modules[0].tags.tree:
         fail(
             msg = "kconfig requires inputs via the `tree` tag",
         )
     if len(module_ctx.modules[0].tags.tree) > 1:
         fail(
             msg = "kconfig only supports a single Kconfig tree",
         )

     zephyr_root = module_ctx.modules[0].tags.tree[0].zephyr_root
     board_name = module_ctx.modules[0].tags.tree[0].board_name
     board_qualifiers = module_ctx.modules[0].tags.tree[0].board_qualifiers

     # Generate a repository to hold all the flags parsed from Kconfig symbols.
     # These flags don't have values yet.
     gen_kconfiglib(
         name = "kconfig",
         zephyr_root = zephyr_root,
         board_name = board_name,
         board_qualifiers = board_qualifiers,
     )

     # Generate one project configs repository for each project.
     for project in module_ctx.modules[0].tags.project:
         # Each project must have one prj.conf file and may have zero or more
         # extra conf files.
         conf_file = project.conf_file
         extra_conf_files = project.extra_conf_files
         # Tell the user the namespace of the generated flags.
         print("Generating Kconfig-Bazel flags in repository: " + project.name)
         gen_projectlib(
             name = project.name,
             zephyr_root = zephyr_root,
             board_name = board_name,
             board_qualifiers = board_qualifiers,
             conf_file = conf_file,
             extra_conf_files = extra_conf_files,
         )

 _kconfig_tree = tag_class(
     attrs = _COMMON_KCONFIG_TREE_ATTRS,
 )
 _kconfig_project = tag_class(
     attrs = {
         "name": attr.string(
             mandatory = True,
         ),
     } | _COMMON_CONF_FILE_ATTRS,
 )

 kconfig = module_extension(
     doc = """kconfig parses a Kconfig tree and generates a repository
 containing Bazel config settings, each corresponding to a Kconfig symbol.
 These config settings can be used with select() to conditionally compile
 sources within Zephyr. Also generates a repository for each configured
 project containing the config setting values parsed from prj.conf.""",
     implementation = _kconfig_impl,
     tag_classes = {
         "tree": _kconfig_tree,
         "project": _kconfig_project,
     },
 )
	# Copyright 2025 The Pigweed Authors
	#
	# Licensed under the Apache License, Version 2.0 (the "License"); you may not
	# use this file except in compliance with the License. You may obtain a copy of
	# the License at
	#
	# https://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	# License for the specific language governing permissions and limitations under
	# the License.

	load("//bazel/private:repo_rule_python.bzl", "COMMON_PY_REPO_RULE_ATTRS", "get_python")

	_COMMON_KCONFIG_TREE_ATTRS = {
	"zephyr_root": attr.label(
	mandatory = True,
	allow_single_file = True,
	),
	"board_name": attr.string(
	mandatory = True,
	),
	"board_qualifiers": attr.string(),
	} \| COMMON_PY_REPO_RULE_ATTRS

	_COMMON_CONF_FILE_ATTRS = {
	"conf_file": attr.label(
	mandatory = True,
	allow_single_file = True,
	),
	"extra_conf_files": attr.label_list(),
	}

	def _construct_environment(repo_ctx):
	srctree = str(repo_ctx.path(repo_ctx.attr.zephyr_root).dirname)

	# Directories to hold outputs of kconfig_gen.
	kconfig_binary_dirname = "Kconfig"
	kconfig_board_dirname = "Kconfig/boards"
	# Zephyr 4.3 added an "env file" in the Kconfig tree. This is for post-build
	# metadata generation but is unconditionally sourced. We create an empty env
	# file here since we don't care about post-build metadata.
	kconfig_env_filename = "kconfig_module_dirs.env"
	repo_ctx.file(kconfig_env_filename)

	environment = {
	"srctree": srctree,
	"ZEPHYR_BASE": srctree,
	"KCONFIG_BINARY_DIR": str(repo_ctx.path(kconfig_binary_dirname)),
	"KCONFIG_BOARD_DIR": str(repo_ctx.path(kconfig_board_dirname)),
	"KCONFIG_ENV_FILE": str(repo_ctx.path(kconfig_env_filename)),
	"BOARD": repo_ctx.attr.board_name,
	"BOARD_QUALIFIERS": repo_ctx.attr.board_qualifiers,
	"ARCH_DIR": srctree + "/arch",
	"HWM_SCHEME": "v2",
	}
	return environment

	def _run_kconfig_gen(repo_ctx, python, environment):
	# Generate Kconfig snippets pointing to soc and arch directories.
	kconfig_gen_script_path = repo_ctx.path(Label("//scripts/build:kconfig_gen.py"))
	repo_ctx.watch(kconfig_gen_script_path)
	srctree = environment["srctree"]
	result = python.execute(
	[
	kconfig_gen_script_path,
	"--arch-root",
	srctree,
	"--soc-root",
	srctree,
	],
	environment=environment,
	)
	if result.return_code != 0:
	fail("Failed to run kconfig_gen (%d):\n%s" % (result.return_code, result.stderr))

	def _write_configs_dot_c(repo_ctx, python, environment):
	# Generate configs.c
	# Only applies to project-specific configs repository.
	configs_c_filename = "generated/configs.c"
	repo_ctx.file(configs_c_filename)
	generate_configs_dot_c_script_path = repo_ctx.path(
	Label("//scripts/build:generate_configs_dot_c.py"))
	repo_ctx.watch(generate_configs_dot_c_script_path)
	args = [
	generate_configs_dot_c_script_path,
	"--autoconf",
	repo_ctx.path("generated/zephyr/autoconf.h"),
	"-o",
	repo_ctx.path(configs_c_filename),
	]
	result = python.execute(
	args,
	environment=environment,
	)
	if result.return_code != 0:
	fail("Failed to generate configs.c from autoconf.h (%d):\n%s" % (result.return_code, result.stderr))

	def _write_build_file(repo_ctx):
	# Declare the autoconf cc library
	# Only applies to project-specific configs repository.
	repo_ctx.file(
	"BUILD.bazel",
	content=
	"""package(default_visibility = ["//visibility:public"])

	cc_library(
	name = "autoconf",
	hdrs = ["generated/zephyr/autoconf.h"],
	includes = ["generated"],
	)

	filegroup(
	name = "configs_file",
	srcs = ["generated/configs.c"],
	)
	""",)

	def _gen_kconfiglib_impl(repo_ctx):
	environment = _construct_environment(repo_ctx)
	srctree = environment["srctree"]
	python = get_python(
	repo_ctx,
	extra_import_paths=[
	# Provide paths to kconfiglib and kconfigfunctions.py.
	srctree + "/scripts/kconfig",
	],
	)
	_run_kconfig_gen(repo_ctx, python, environment)

	# Parse the Kconfig tree.
	build_file_name = "BUILD.bazel"
	build_file_path = repo_ctx.path(build_file_name)
	repo_ctx.file(build_file_name)
	bazel_config_script_path = repo_ctx.path(Label("//scripts/build:bazel_config.py"))
	repo_ctx.watch(bazel_config_script_path)
	args = [
	bazel_config_script_path,
	"--kconfig",
	srctree + "/Kconfig",
	"gen_kconfig",
	"-o",
	build_file_path,
	]
	result = python.execute(
	args,
	environment=environment,
	)
	if result.return_code != 0:
	fail("Failed to generate kconfig BUILD file (%d):\n%s" % (result.return_code, result.stderr))

	gen_kconfiglib = repository_rule(
	implementation = _gen_kconfiglib_impl,
	attrs = _COMMON_KCONFIG_TREE_ATTRS,
	)

	def _gen_projectlib_impl(repo_ctx, python, environment):
	environment = _construct_environment(repo_ctx)
	srctree = environment["srctree"]
	python = get_python(
	repo_ctx,
	extra_import_paths=[
	# Provide paths to kconfiglib and kconfigfunctions.py.
	srctree + "/scripts/kconfig",
	],
	)
	_run_kconfig_gen(repo_ctx, environment)

	# Parse the Kconfig tree.
	bazel_config_script_path = repo_ctx.path(Label("//scripts/build:bazel_config.py"))
	repo_ctx.watch(bazel_config_script_path)
	bzl_file_name = "kconfig_flag_values.bzl"
	bzl_file_path = repo_ctx.path(bzl_file_name)
	repo_ctx.file(bzl_file_name)
	args = [
	bazel_config_script_path,
	"--kconfig",
	srctree + "/Kconfig",
	"gen_project",
	"--project",
	str(repo_ctx.path(repo_ctx.attr.conf_file)),
	"-o",
	bzl_file_path,
	"--extra_configs_in",
	]
	for config in repo_ctx.attr.extra_conf_files:
	args.append(repo_ctx.path(config))
	repo_ctx.file("generated/zephyr/autoconf.h")
	result = python.execute(
	args,
	environment=environment,
	)
	if result.return_code != 0:
	fail("Failed to generate kconfig BUILD file (%d):\n%s" % (result.return_code, result.stderr))

	_write_configs_dot_c(repo_ctx)
	_write_build_file(repo_ctx)

	gen_projectlib = repository_rule(
	implementation = _gen_projectlib_impl,
	attrs = _COMMON_KCONFIG_TREE_ATTRS \| _COMMON_CONF_FILE_ATTRS,
	)

	def _kconfig_impl(module_ctx):
	if not module_ctx.modules[0].tags.tree:
	fail(
	msg = "kconfig requires inputs via the `tree` tag",
	)
	if len(module_ctx.modules[0].tags.tree) > 1:
	fail(
	msg = "kconfig only supports a single Kconfig tree",
	)

	zephyr_root = module_ctx.modules[0].tags.tree[0].zephyr_root
	board_name = module_ctx.modules[0].tags.tree[0].board_name
	board_qualifiers = module_ctx.modules[0].tags.tree[0].board_qualifiers

	# Generate a repository to hold all the flags parsed from Kconfig symbols.
	# These flags don't have values yet.
	gen_kconfiglib(
	name = "kconfig",
	zephyr_root = zephyr_root,
	board_name = board_name,
	board_qualifiers = board_qualifiers,
	)

	# Generate one project configs repository for each project.
	for project in module_ctx.modules[0].tags.project:
	# Each project must have one prj.conf file and may have zero or more
	# extra conf files.
	conf_file = project.conf_file
	extra_conf_files = project.extra_conf_files
	# Tell the user the namespace of the generated flags.
	print("Generating Kconfig-Bazel flags in repository: " + project.name)
	gen_projectlib(
	name = project.name,
	zephyr_root = zephyr_root,
	board_name = board_name,
	board_qualifiers = board_qualifiers,
	conf_file = conf_file,
	extra_conf_files = extra_conf_files,
	)

	_kconfig_tree = tag_class(
	attrs = _COMMON_KCONFIG_TREE_ATTRS,
	)
	_kconfig_project = tag_class(
	attrs = {
	"name": attr.string(
	mandatory = True,
	),
	} \| _COMMON_CONF_FILE_ATTRS,
	)

	kconfig = module_extension(
	doc = """kconfig parses a Kconfig tree and generates a repository
	containing Bazel config settings, each corresponding to a Kconfig symbol.
	These config settings can be used with select() to conditionally compile
	sources within Zephyr. Also generates a repository for each configured
	project containing the config setting values parsed from prj.conf.""",
	implementation = _kconfig_impl,
	tag_classes = {
	"tree": _kconfig_tree,
	"project": _kconfig_project,
	},
	)