rules_kconfig

Bazel rules for parsing Kconfig files and generating equivalent Bazel build settings and config.h headers.

Module extension

The primary interface is the kconfig module extension. Each kconfig.repo tag parses a Kconfig file tree and generates a repository containing:

A bool_flag, int_flag, or string_flag for every config symbol.
A cc_library target (:config) that provides config.h reflecting the active flag values.

kconfig = use_extension("@rules_kconfig//kconfig:extensions.bzl", "kconfig")
kconfig.repo(
    name = "my_kconfig",
    kconfig = "//:Kconfig",
    interpreter = "@python_3_12_host//:python",
)
use_repo(kconfig, "my_kconfig")

Use kconfig.overrides to overlay a .config file onto an external kconfig repository via a Starlark transition:

kconfig.overrides(
    name = "my_board_config",
    kconfig = "@ext_kconfig//:ext_kconfig",
    config = "//:.config",
    interpreter = "@python_3_12_host//:python",
)
use_repo(kconfig, "my_board_config")

See the Introduction for full setup and usage instructions.

Repository Rules

kconfig_overrides_repository
kconfig_repository

kconfig_library

load("@rules_kconfig//kconfig:defs.bzl", "kconfig_library")

kconfig_library(name, deps, srcs, root)

Collect Kconfig source files into a single provider for use by menuconfig and repository rules.

All source files must be real (non-generated) files. If a single source is provided, it is automatically treated as the root. When multiple sources are present, set root explicitly to indicate the top-level Kconfig entry point. Transitive sources from deps are included in the provider.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
deps	Other `kconfig_library` targets whose sources should be included transitively.	List of labels	optional	`[]`
srcs	Kconfig source files. Must be real (non-generated) files.	List of labels	optional	`[]`
root	The top-level Kconfig file. Inferred automatically when `srcs` contains exactly one file.	Label	optional	`None`

kconfig_toolchain

load("@rules_kconfig//kconfig:defs.bzl", "kconfig_toolchain")

kconfig_toolchain(name, kconfiglib)

Declares a kconfig toolchain backed by kconfiglib.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
kconfiglib	A py_library providing kconfiglib.	Label	required

menuconfig

load("@rules_kconfig//kconfig:defs.bzl", "menuconfig")

menuconfig(name, config, kconfig)

Launch kconfiglib's menuconfig TUI for interactive Kconfig editing.

Run with bazel run to interactively create or edit a .config file against a Kconfig tree. The TUI writes the resulting configuration to the path specified by config (relative to the workspace root).

ATTRIBUTES

Name	Description	Type	Mandatory
name	A unique name for this target.	Name	required
config	Workspace-relative path to the `.config` file to read/write.	String	required
kconfig	A kconfig_library target providing the Kconfig source tree.	Label	required

KConfigInfo

load("@rules_kconfig//kconfig:defs.bzl", "KConfigInfo")

KConfigInfo(root, srcs)

Encapsulates a Kconfig source tree: an optional root file and all source files (direct and transitive).

FIELDS

Name	Description
root	Optional[File]: The top-level Kconfig file that kconfiglib should parse. May be None when a library contributes sources but is not itself a root.
srcs	depset[File]: All Kconfig source files (direct and transitive) reachable from this library.

kconfig_overrides_repository

load("@rules_kconfig//kconfig:defs.bzl", "kconfig_overrides_repository")

kconfig_overrides_repository(name, config, interpreter, kconfig, kconfiglib_anchor)

Overlay .config values onto an existing kconfig repository.

Reads the manifest from the source kconfig repository to locate the symlinked Kconfig source tree, then reparses with kconfiglib and a user-provided .config file. If the source repository was itself created with a .config, the overrides are stacked on top of those base values. Generates a defs.bzl containing a Starlark transition and wrapper rule that apply the overrides.

Values explicitly set on the command line take precedence over the overlay.

The generated defs.bzl creates the transition and rule:

rule	description
`kconfig_override_transition`	A transition that applies transitions for each default in `.config`
`with_kconfig_overrides`	A rule similar to `alias` that applies `kconfig_override_transition` to the target

Use with_kconfig_overrides to wrap a kconfig-dependent target:

load("@base_kconfig_override//:defs.bzl", "with_kconfig_overrides")

with_kconfig_overrides(
    name = "config",
    actual = ":consumer_of_base",
)

ATTRIBUTES

Name	Description	Type	Mandatory
name	A unique name for this repository.	Name	required
config	.config file with override values.	Label	required
interpreter	A Python interpreter target used to run the generator.	Label	required
kconfig	Label to the kconfig manifest from the source kconfig repository (e.g. `@my_kconfig//:my_kconfig`).	Label	required
kconfiglib_anchor	Label used to locate the `kconfiglib` package. Managed by the module extension.	Label	required

kconfig_repository

load("@rules_kconfig//kconfig:defs.bzl", "kconfig_repository")

kconfig_repository(name, apparent_name, defaults, interpreter, kconfig, kconfiglib_anchor)

Parse a Kconfig file tree and generate a Bazel repository with build settings.

The generated repository contains a bool_flag, int_flag, or string_flag for every config symbol found in the Kconfig tree, plus a cc_library target (:config) providing a config.h header that reflects the active flag values.

The Kconfig source tree is symlinked into kconfig_srcs/ and a kconfig.manifest.json records the root file and all visited files. A repo-named symlink (e.g. @my_kconfig//:my_kconfig) points to the manifest for downstream consumers.

Prefer using the kconfig module extension rather than calling this rule directly.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this repository.	Name	required
apparent_name	The user-facing repository name (used for the repo-named symlink). Defaults to the canonical name.	String	optional	`""`
defaults	Optional .config file with explicit symbol values that override Kconfig defaults.	Label	optional	`None`
interpreter	A Python interpreter target used to run the Kconfig parser.	Label	required
kconfig	The root Kconfig file to parse. All files referenced via `source` directives are followed automatically.	Label	required
kconfiglib_anchor	Label used to locate the `kconfiglib` package. Managed by the module extension.	Label	required

kconfig

kconfig = use_extension("@rules_kconfig//kconfig:defs.bzl", "kconfig")
kconfig.overrides(name, config, interpreter, kconfig)
kconfig.repo(name, defaults, interpreter, kconfig)

Configure kconfig repositories.

TAG CLASSES

overrides

Overlay .config overrides onto an existing kconfig repository.

Attributes

Name	Description	Type	Mandatory
name	The name of the generated overrides repository.	Name	required
config	.config file with override values.	Label	required
interpreter	A Python interpreter target (e.g. `@python_3_12_host//:python`).	Label	required
kconfig	Label to the kconfig manifest from the source repository (e.g. `@ext_kconfig//:ext_kconfig`).	Label	required

repo

Declare a kconfig repository to be generated from a Kconfig file tree.

Attributes

Name	Description	Type	Mandatory	Default
name	The name of the generated repository. Symbols are accessible as `@<name>//:CONFIG_<symbol>`.	Name	required
defaults	Optional .config file providing default overrides for Kconfig symbols.	Label	optional	`None`
interpreter	A Python interpreter target used to run the Kconfig parser (e.g. `@python_3_12_host//:python`).	Label	required
kconfig	The root Kconfig file to parse. All files referenced via `source` directives are followed automatically.	Label	required

rules_kconfig

rules_kconfig

Module extension

Rules

Providers

Repository Rules

Module Extensions

kconfig_library

kconfig_toolchain

menuconfig

KConfigInfo

kconfig_overrides_repository

kconfig_repository

kconfig

overrides

repo