Re: [PATCH v3] Documentation/kbuild: Document the kconfig choice default value

Masahiro Yamada
2021-08-05T12:48:37Z

On Tue, Jul 20, 2021 at 5:29 AM Robert Richter <rrichter@amd.com> wrote:
>
> Document how choice defaults are determined:
>
> Default of a choice is its first visible choice element unless it is
> explicitly set by the 'default' property [1]. Choice elements do not
> support default attributes. [2]
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig/symbol.c?h=v5.14-rc1#n245
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig/menu.c?h=v5.14-rc1#n494
>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
> v3: Fix base of v2 (rebased onto v5.14-rc2)
> v2: clarification on 'default' attribute of a choice
> added example
> ---
> Documentation/kbuild/kconfig-language.rst | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst
> index 98c24183d8c3..d919dde0bcbf 100644
> --- a/Documentation/kbuild/kconfig-language.rst
> +++ b/Documentation/kbuild/kconfig-language.rst
> @@ -417,6 +417,21 @@ definitions of that choice. If a [symbol] is associated to the choice,
> then you may define the same choice (i.e. with the same entries) in another
> place.
>
> +The default value of a choice is set to the first visible choice
> +element unless it is explicitly set by the 'default' property.
> +
> +Note:
> + Choice options do not support the 'default' attribute.
> +
> +E.g.::
> +
> + choice
> + default C1
> + config C0
> + config C1
> + # no default attribute here
> + endchoice
> +
> comment::
>
> "comment" <prompt>
> --
> 2.29.2
>

I am not sure whether this note is needed or not,
anyway the code example is wrong.

Kconfig:3:warning: config symbol defined without type
Kconfig:4:warning: config symbol defined without type
Kconfig:3:warning: choice value must have a prompt
Kconfig:4:warning: choice value must have a prompt
Kconfig:1:warning: config symbol defined without type
Kconfig:1:warning: choice must have a prompt

--
Best Regards
Masahiro Yamada