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authorMasahiro Yamada <masahiroy@kernel.org>2020-03-02 15:23:39 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2020-03-13 10:05:34 +0900
commitdef2fbffe62c00c330c7f41584a356001179c59c (patch)
treea54378cb937f472f0d000ce1d41872791f4457b3 /Documentation/kbuild
parent1cd9b3abf5332102d4d967555e7ed861a75094bf (diff)
downloadlinux-def2fbffe62c00c330c7f41584a356001179c59c.tar.gz
kconfig: allow symbols implied by y to become m
The 'imply' keyword restricts a symbol to y or n, excluding m
when it is implied by y. This is the original behavior since
commit 237e3ad0f195 ("Kconfig: Introduce the "imply" keyword").

However, the author of this feature, Nicolas Pitre, stated that
the 'imply' keyword should not impose any restrictions.
(https://lkml.org/lkml/2020/2/19/714)

I agree, and want to get rid of this tricky behavior.

Suggested-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Diffstat (limited to 'Documentation/kbuild')
-rw-r--r--Documentation/kbuild/kconfig-language.rst12
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/kbuild/kconfig-language.rst b/Documentation/kbuild/kconfig-language.rst
index d0111dd26410..d4d988aea679 100644
--- a/Documentation/kbuild/kconfig-language.rst
+++ b/Documentation/kbuild/kconfig-language.rst
@@ -173,7 +173,7 @@ applicable everywhere (see syntax).
 	===		===		=============	==============
 	n		y		n		N/m/y
 	m		y		m		M/y/n
-	y		y		y		Y/n
+	y		y		y		Y/m/n
 	y		n		*		N
 	===		===		=============	==============
 
@@ -181,6 +181,16 @@ applicable everywhere (see syntax).
   ability to hook into a secondary subsystem while allowing the user to
   configure that subsystem out without also having to unset these drivers.
 
+  Note: If the combination of FOO=y and BAR=m causes a link error,
+  you can guard the function call with IS_REACHABLE()::
+
+	foo_init()
+	{
+		if (IS_REACHABLE(CONFIG_BAZ))
+			baz_register(&foo);
+		...
+	}
+
 - limiting menu display: "visible if" <expr>
 
   This attribute is only applicable to menu blocks, if the condition is