From: Randy Dunlap <randy.dunlap@xxxxxxxxxx> 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 <randy.dunlap@xxxxxxxxxx> --- Documentation/kbuild/kconfig-language.txt | 22 ++++++++++++++++++++ 1 file changed, 22 insertions(+) --- lnx-2639-rc5.orig/Documentation/kbuild/kconfig-language.txt +++ lnx-2639-rc5/Documentation/kbuild/kconfig-language.txt @@ -381,3 +381,25 @@ 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" +endif + +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. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
