[PATCH RFC next 09/18] kbuild: support W=c and W=e shorthands for Kconfig

[Ilias Apalodimas]

On Mon, 4 May 2026 at 16:20, Quentin Schulz <foss+uboot at 0leil.net> wrote:
>
> From: Quentin Schulz <quentin.schulz at cherry.de>
>
> [ Upstream commit c77d06e70d59cbc6e3c22bf644bb0b197a5fc182 ]
>
> Original commit log:
>
>   KCONFIG_WARN_UNKNOWN_SYMBOLS=1 and KCONFIG_WERROR=1 are descriptive
>   and suitable in scripting, but typing them from the command line can
>   be tedious.
>
>   Associate them with KBUILD_EXTRA_WARN (and the W= shorthand).
>
>   Support a new letter 'c' to enable extra checks in Kconfig. You can
>   still manage compiler warnings (W=1) and Kconfig warnings (W=c)
>   independently.
>
>   Reuse the letter 'e' to turn Kconfig warnings into errors.
>
>   As usual, you can combine multiple letters in KCONFIG_EXTRA_WARN.
>
>     $ KCONFIG_WARN_UNKNOWN_SYMBOLS=1 KCONFIG_WERROR=1 make defconfig
>
>   can be shortened to:
>
>     $ KBUILD_EXTRA_WARN=ce make defconfig
>
>   or, even shorter:
>
>     $ make W=ce defconfig
>
> [note that U-Boot currently doesn't make use of the KCONFIG_WERROR or
>  KCONFIG_WARN_UNKNOWN_SYMBOLS symbols as we're using an ancient version
>  of kconfig, so technically W=c won't do anything.]
> Signed-off-by: Quentin Schulz <quentin.schulz at cherry.de>
> ---

Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>

>  Makefile                   | 10 ++++++++++
>  scripts/Makefile.extrawarn |  9 ---------
>  scripts/kconfig/Makefile   |  8 ++++++++
>  3 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index aed54cee4a4..bd33437fdfd 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -105,6 +105,15 @@ endif
>
>  export quiet Q KBUILD_VERBOSE
>
> +# backward compatibility
> +KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
> +
> +ifeq ("$(origin W)", "command line")
> +  KBUILD_EXTRA_WARN := $(W)
> +endif
> +
> +export KBUILD_EXTRA_WARN
> +
>  # Kbuild will save output files in the current working directory.
>  # This does not need to match to the root of the kernel source tree.
>  #
> @@ -2745,6 +2754,7 @@ help:
>         @echo  '                1: warnings which may be relevant and do not occur too often'
>         @echo  '                2: warnings which occur quite often but may still be relevant'
>         @echo  '                3: more obscure warnings, can most likely be ignored'
> +       @echo  '                c: extra checks in the configuration stage (Kconfig)'
>         @echo  '                e: warnings are being treated as errors'
>         @echo  '                Multiple levels can be combined with W=12 or W=123'
>         @echo  ''
> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
> index 6bbba36c596..b1881d83e06 100644
> --- a/scripts/Makefile.extrawarn
> +++ b/scripts/Makefile.extrawarn
> @@ -8,15 +8,6 @@
>
>  KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
>
> -# backward compatibility
> -KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
> -
> -ifeq ("$(origin W)", "command line")
> -  KBUILD_EXTRA_WARN := $(W)
> -endif
> -
> -export KBUILD_EXTRA_WARN
> -
>  #
>  # W=1 - warnings which may be relevant and do not occur too often
>  #
> diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> index abc34f60d15..f072772eba8 100644
> --- a/scripts/kconfig/Makefile
> +++ b/scripts/kconfig/Makefile
> @@ -22,6 +22,14 @@ ifeq ($(quiet),silent_)
>  silent := -s
>  endif
>
> +ifneq ($(findstring c, $(KBUILD_EXTRA_WARN)),)
> +export KCONFIG_WARN_UNKNOWN_SYMBOLS=1
> +endif
> +
> +ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
> +export KCONFIG_WERROR=1
> +endif
> +
>  # We need this, in case the user has it in its environment
>  unexport CONFIG_
>
>
> --
> 2.54.0
>