diff --git a/tools/building.py b/tools/building.py
index d855aaebdcb0ebbfd449a92bffa0437c59a13a26..6660ed81879fad891274c0df244620b0ca874cd0 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -285,6 +285,16 @@ def PrepareBuilding(env, root_directory, has_libcpu=False, remove_components = [
             menuconfig(Rtt_Root)
             exit(0)
 
+    AddOption('--useconfig',
+                dest = 'useconfig',
+                type='string',
+                help = 'make rtconfig.h from config file.')
+    configfn = GetOption('useconfig')
+    if configfn:
+        from menuconfig import mk_rtconfig
+        mk_rtconfig(configfn)
+        exit(0)
+
     # add comstr option
     AddOption('--verbose',
                 dest='verbose',
diff --git a/tools/menuconfig.py b/tools/menuconfig.py
index c55509068d853d128120fe6f558e47cacec64382..004a338d811a4fe5abc3fd155567e38177afd0fb 100644
--- a/tools/menuconfig.py
+++ b/tools/menuconfig.py
@@ -6,7 +6,7 @@ def mk_rtconfig(filename):
     try:
         config = file(filename)
     except:
-        print 'open .config failed'
+        print('open config:%s failed' % filename)
         return
 
     rtconfig = file('rtconfig.h', 'w')