Index: tools/config.py
===================================================================
--- tools/config.py	(revision d162f1b60e948e0831eac7af493a2ff32b33b952)
+++ tools/config.py	(revision 095ed4a4a5ddf557d343fea0988b25a4e6647b15)
@@ -46,4 +46,5 @@
 ARGPOS_CHOICE = 3
 ARGPOS_PRESET = 4
+ARGPOS_MASK_PLATFORM = 3
 
 RULES_FILE = sys.argv[ARGPOS_RULES]
@@ -691,4 +692,6 @@
 		preset = None
 
+	mask_platform = (len(sys.argv) > ARGPOS_MASK_PLATFORM and sys.argv[ARGPOS_MASK_PLATFORM] == "--mask-platform")
+
 	# Input configuration file can be specified on command line
 	# otherwise configuration from previous run is used.
@@ -756,7 +759,9 @@
 			options = []
 			opt2row = {}
-			cnt = 1
-
-			options.append("  --- Load preconfigured defaults ... ")
+			cnt = 0
+
+			if not mask_platform:
+				cnt += 1
+				options.append("  --- Load preconfigured defaults ... ")
 
 			for rule in rules:
@@ -764,4 +769,7 @@
 
 				if cond and not cond.evaluate(config):
+					continue
+
+				if mask_platform and (varname == "PLATFORM" or varname == "MACHINE" or varname == "COMPILER"):
 					continue
 
@@ -812,5 +820,5 @@
 					continue
 
-			if value == 0:
+			if value == 0 and not mask_platform:
 				profile = choose_profile(PRESETS_DIR, MAKEFILE, screen, config)
 				if profile != None: