Re: [PATCH v1 00/10] tools: Introduce a kernel configuration checker

[Nicolas Schier <nsc@kernel.org>]

On Fri, Nov 06, 2026 at 10:19:12AM +0100, Ahmed S. Darwish wrote:
> Hi,
> 
> A month ago in Prague I proposed a kernel configuration checker:
> 
>     PREEMPT_RT configuration: Best practices with kconfig-checker
>     https://youtu.be/hqnOmdpGBdQ
> 
> This series adds kconfig-checker: a Python tool that checks the kernel
> .config against a set of YAML rules and reports all issues by severity.
> 
> The series also adds:
> 
>      - a PREEMPT_RT configuration ruleset
>      - a make checkconfig target
>      - support for ruleset overlays
> 
> Example:
> 
>     $ make defconfig
>     $ ./tools/kconfig-checker/check.py check -c .config -r preempt_rt
> 
>       Configuration Issues with severity = FATAL
>       ==========================================
> 
>       * CONFIG_PREEMPT_RT is not in .config
> 
>         Rationale:
>         https://docs.kernel.org/core-api/real-time/kernel-configuration.html#config-preempt-rt
> 
>       Configuration Issues with severity = HIGH
>       =========================================
> 
>       * CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE is unset
> 
>         Rationale:
>         https://docs.kernel.org/core-api/real-time/kernel-configuration.html#config-cpu-freq-default-gov-performance
> 
>       * Below options are set:
> 
>         CONFIG_SLUB_DEBUG
> 
>         Rationale:
>         https://docs.kernel.org/core-api/real-time/kernel-configuration.html#kernel-debug-options
> 
>       Configuration Issues with severity = MEDIUM
>       ===========================================
> 
>       * Below options are set:
> 
>         CONFIG_CPU_FREQ_GOV_USERSPACE
>         CONFIG_CPU_FREQ_GOV_ONDEMAND
> 
>         Rationale:
>         https://docs.kernel.org/core-api/real-time/kernel-configuration.html#non-performance-cpu-frequency-governors
> 
>       ### ...
>       ### More output
>       ### ...
> 
> The same check can be run through make:
> 
>     $ make RULES=preempt_rt checkconfig
> 
> If no ruleset is specified, the target prints the available rulesets:
> 
>     $ make checkconfig
>       Usage: make RULES=<profile> [OVERLAY=<overlay>] checkconfig
>       Available RULES: preempt_rt
> 
> The overlay mechanism allows distributions, CI systems, and Board Support
> Packages to apply additional policy or override existing mainline rules.
> 
> For example:
> 
>     $ ./tools/kconfig-checker/check.py check	\
>           -c path/to/.config			\
>           -r preempt_rt				\
>           -o path/to/overlay.yml
> 
> or:
> 
>     $ make RULES=preempt_rt OVERLAY=path/to/overlay.yml checkconfig
> 
> Patch 09/10 documents the overlay format and gives an example use case.
> 
> My goal is to get this into the kernel and have Debian's PREEMPT_RT kernel
> packaging to use it.  I'd also like systemd to use it: its README lists 60
> kernel CONFIG_* symbols with different requirements severity.
> 
> Thank you!
> Ahmed
> 
> 8<-----
> 
> Ahmed S. Darwish (10):
>   kconfig-checker: Add schema for rule files
>   kconfig-checker: Introduce PREEMPT_RT configuration rules
>   kconfig-checker: Add the configuration checker code
>   kconfig: Introduce checkconfig target
>   Documentation: Describe kconfig-checker usage and design
>   kconfig-checker: Split schema to support component reuse
>   kconfig-checker: Introduce overlays schema
>   kconfig-checker: Add support for rule overlays
>   Documentation: Describe kconfig-checker overlays
>   kconfig: Introduce OVERLAY= for make checkconfig
> 
>  Documentation/admin-guide/README.rst          |  29 +
>  .../real-time/kernel-configuration.rst        |   3 +
>  Documentation/tools/index.rst                 |   1 +
>  Documentation/tools/kconfig_checker.rst       | 101 +++
>  scripts/kconfig/Makefile                      |  25 +
>  tools/kconfig-checker/check.py                | 686 ++++++++++++++++++
>  tools/kconfig-checker/rules/preempt_rt.yml    | 169 +++++
>  tools/kconfig-checker/schemas/base.yml        | 114 +++
>  tools/kconfig-checker/schemas/overlay.yml     |  28 +
>  tools/kconfig-checker/schemas/rules.yml       |  20 +
>  10 files changed, 1176 insertions(+)

Thanks!  I know some people who are definitly interested in such a
config policy checker.

Please prepare a new MAINTAINERS entry in a respin.  Are you planning to
maintain it after inclusion?


-- 
Nicolas