Hi Nicolas,
On Tue, Mar 3, 2020 at 12:31 AM Nicolas Pitre <nico@xxxxxxxxxxx> wrote:
>
> On Mon, 2 Mar 2020, Masahiro Yamada wrote:
>
> > 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 the 'imply' keyword, Nicolas Pitre, stated
> > that the 'imply' keyword should not impose any restrictions. [1]
> >
> > I agree, and want to get rid of this tricky behavior.
> >
> > [1]: https://lkml.org/lkml/2020/2/19/714
> >
> > Suggested-by: Nicolas Pitre <nico@xxxxxxxxxxx>
> > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
>
> Acked-by: Nicolas Pitre <nico@xxxxxxxxxxx>
>
> In addition to the IS_REACHABLE() note, it might be a good idea to
> suggest adding an "imply" reference to the dependency if the feature
> provided by BAZ is highli desirable, e.g.:
>
> config FOO
> tristate
> imply BAR
> imply BAZ
>
OK, this info is more relevant to the 2nd patch.
I folded this following to 2/2.
diff --git a/Documentation/kbuild/kconfig-language.rst
b/Documentation/kbuild/kconfig-language.rst
index 68719e78ff85..a1601ec3317b 100644
--- a/Documentation/kbuild/kconfig-language.rst
+++ b/Documentation/kbuild/kconfig-language.rst
@@ -194,6 +194,14 @@ applicable everywhere (see syntax).
...
}
+ Note: If the feature provided by BAZ is highly desirable for FOO,
+ FOO should imply not only BAZ, but also its dependency BAR::
+
+ config FOO
+ tristate "foo"
+ imply BAR
+ imply BAZ
+
- limiting menu display: "visible if" <expr>
This attribute is only applicable to menu blocks, if the condition is
Both applied.
> > ---
> >
> > Documentation/kbuild/kconfig-language.rst | 12 +++++++++++-
> > scripts/kconfig/symbol.c | 5 +----
> > 2 files changed, 12 insertions(+), 5 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
> > diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
> > index 8d38b700b314..b101ef3c377a 100644
> > --- a/scripts/kconfig/symbol.c
> > +++ b/scripts/kconfig/symbol.c
> > @@ -401,8 +401,7 @@ void sym_calc_value(struct symbol *sym)
> > sym_warn_unmet_dep(sym);
> > newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
> > }
> > - if (newval.tri == mod &&
> > - (sym_get_type(sym) == S_BOOLEAN || sym->implied.tri == yes))
> > + if (newval.tri == mod && sym_get_type(sym) == S_BOOLEAN)
> > newval.tri = yes;
> > break;
> > case S_STRING:
> > @@ -484,8 +483,6 @@ bool sym_tristate_within_range(struct symbol *sym, tristate val)
> > return false;
> > if (sym->visible <= sym->rev_dep.tri)
> > return false;
> > - if (sym->implied.tri == yes && val == mod)
> > - return false;
> > if (sym_is_choice_value(sym) && sym->visible == yes)
> > return val == yes;
> > return val >= sym->rev_dep.tri && val <= sym->visible;
> > --
> > 2.17.1
> >
> >
--
Best Regards
Masahiro Yamada
