Index: tools/config.py
===================================================================
--- tools/config.py	(revision 095ed4a4a5ddf557d343fea0988b25a4e6647b15)
+++ tools/config.py	(revision 3f1a4818c8d7a210c6274be039dfa6b2a8dc3dbc)
@@ -772,5 +772,5 @@
 
 				if mask_platform and (varname == "PLATFORM" or varname == "MACHINE" or varname == "COMPILER"):
-					continue
+					rule = varname, vartype, "(locked) " + name, choices, cond
 
 				if varname == selname:
@@ -837,4 +837,7 @@
 			else:
 				value = config[selname]
+
+			if mask_platform and (selname == "PLATFORM" or selname == "MACHINE" or selname == "COMPILER"):
+					continue
 
 			if seltype == 'choice':