diff options
authorRandy Dunlap <>2011-04-28 10:58:52 -0700
committerMichal Marek <>2011-05-02 17:39:24 +0200
commit64b81ed7fb1e45c914317b20316f32827bc6444b (patch)
parentdf835c2e7fa875618cc14ced0110ea96f79536fb (diff)
kconfig-language: add to hints
Explain a little about kconfig symbol dependencies and symbol existence given optional kconfig language scenarios. Yes, I was bitten by this. Signed-off-by: Randy Dunlap <> Signed-off-by: Michal Marek <>
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index 48a3981c717b..44e2649fbb29 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -389,3 +389,25 @@ config FOO
limits FOO to module (=m) or disabled (=n).
+Kconfig symbol existence
+The following two methods produce the same kconfig symbol dependencies
+but differ greatly in kconfig symbol existence (production) in the
+generated config file.
+case 1:
+config FOO
+ tristate "about foo"
+ depends on BAR
+vs. case 2:
+if BAR
+config FOO
+ tristate "about foo"
+In case 1, the symbol FOO will always exist in the config file (given
+no other dependencies). In case 2, the symbol FOO will only exist in
+the config file if BAR is enabled.