kconfig: environment symbol support

Add the possibility to import a value from the environment into kconfig
via the option syntax. Beside flexibility this has the advantage
providing proper dependencies.
Documented the options syntax.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 3637d1057e13..e6ef171e5b14 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -15,7 +15,7 @@ static struct menu **last_entry_ptr;
 struct file *file_list;
 struct file *current_file;
 
-static void menu_warn(struct menu *menu, const char *fmt, ...)
+void menu_warn(struct menu *menu, const char *fmt, ...)
 {
         va_list ap;
         va_start(ap, fmt);
@@ -172,6 +172,9 @@ void menu_add_option(int token, char *arg)
                 else if (sym_defconfig_list != current_entry->sym)
                         zconf_error("trying to redefine defconfig symbol");
                 break;
+        case T_OPT_ENV:
+                prop_add_env(arg);
+                break;
         }
 }