Thread (6 messages) 6 messages, 2 authors, 2021-08-05

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

From: Masahiro Yamada <masahiroy@kernel.org>
Date: 2021-08-05 12:48:39
Also in: linux-doc, lkml

On Tue, Jul 20, 2021 at 5:29 AM Robert Richter [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <redacted>
---
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
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