[PATCH] .config checks updated

From: Sam Ravnborg <sam@ravnborg.org>

When building a kernel right after 'make mrproper' resulted in a very short
run, and no sign that .config was missing.  This has been fixed by adding a
new rule for .config in the top-level Makefile, and a new target
'silentoldconfig' in scripts/kconfig/Makefile.

Cleaned up a bit in scripts/kconfig/Makefile

Makefile

@@ -268,8 +268,19 @@ scripts:
 # Detect when mixed targets is specified, and make a second invocation
 # of make so .config is not included in this case either (for *config).
 
+no-dot-config-targets := clean mrproper distclean \
+			 cscope TAGS tags help %docs check%
+
 config-targets := 0
 mixed-targets  := 0
+dot-config     := 1
+
+ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
+	ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
+		dot-config := 0
+	endif
+endif
+
 ifneq ($(filter config %config,$(MAKECMDGOALS)),)
 	config-targets := 1
 	ifneq ($(filter-out config %config,$(MAKECMDGOALS)),)
@@ -309,7 +320,26 @@ libs-y		:= lib/
 core-y		:= usr/
 SUBDIRS		:=
 
--include .config
+ifeq ($(dot-config),1)
+# In this section, we need .config
+
+# Read in dependencies to all Kconfig* files, make sure to run
+# oldconfig if changes are detected.
+-include .config.cmd
+
+include .config
+
+# If .config needs to be updated, it will be done via the dependency
+# that autoconf has on .config.
+# To avoid any implicit rule to kick in, define an empty command
+.config: ;
+
+# If .config is newer than include/linux/autoconf.h, someone tinkered
+# with it and forgot to run make oldconfig
+include/linux/autoconf.h: scripts/fixdep .config
+	$(Q)$(MAKE) $(build)=scripts/kconfig silentoldconfig
+
+endif
 
 include arch/$(ARCH)/Makefile
 
@@ -338,15 +368,7 @@ libs-y		:= $(libs-y1) $(libs-y2)
 
 # Here goes the main Makefile
 # ---------------------------------------------------------------------------
-#
-# If the user gave a *config target, it'll be handled in another
-# section below, since in this case we cannot include .config
-# Same goes for other targets like clean/mrproper etc, which
-# don't need .config, either
 
-#	In this section, we need .config
-
--include .config.cmd
 
 ifndef CONFIG_FRAME_POINTER
 CFLAGS		+= -fomit-frame-pointer
@@ -521,13 +543,6 @@ include/config/MARKER: scripts/split-include include/linux/autoconf.h
 	@scripts/split-include include/linux/autoconf.h include/config
 	@touch $@
 
-# 	if .config is newer than include/linux/autoconf.h, someone tinkered
-# 	with it and forgot to run make oldconfig
-
-include/linux/autoconf.h: .config scripts/fixdep
-	$(Q)$(MAKE) $(build)=scripts/kconfig scripts/kconfig/conf
-	./scripts/kconfig/conf -s arch/$(ARCH)/Kconfig
-
 # Generate some files
 # ---------------------------------------------------------------------------
 

scripts/kconfig/Makefile

@@ -2,40 +2,43 @@
 # Kernel configuration targets
 # These targets are used from top-level makefile
 
-.PHONY: oldconfig xconfig gconfig menuconfig config
+.PHONY: oldconfig xconfig gconfig menuconfig config silentoldconfig
 
-xconfig: scripts/kconfig/qconf
-	./scripts/kconfig/qconf arch/$(ARCH)/Kconfig
+xconfig: $(obj)/qconf
+	$< arch/$(ARCH)/Kconfig
 
-gconfig: scripts/kconfig/gconf
-	./scripts/kconfig/gconf arch/$(ARCH)/Kconfig
+gconfig: $(obj)/gconf
+	./$<  arch/$(ARCH)/Kconfig
 
-menuconfig: scripts/kconfig/mconf
+menuconfig: $(obj)/mconf
 	$(Q)$(MAKE) $(build)=scripts/lxdialog
-	./scripts/kconfig/mconf arch/$(ARCH)/Kconfig
+	$< arch/$(ARCH)/Kconfig
 
-config: scripts/kconfig/conf
-	./scripts/kconfig/conf arch/$(ARCH)/Kconfig
+config: $(obj)/conf
+	$< arch/$(ARCH)/Kconfig
 
-oldconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -o arch/$(ARCH)/Kconfig
+oldconfig: $(obj)/conf
+	$< -o arch/$(ARCH)/Kconfig
+
+silentoldconfig: $(obj)/conf
+	$< -s arch/$(ARCH)/Kconfig
 
 .PHONY: randconfig allyesconfig allnoconfig allmodconfig defconfig
 
-randconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -r arch/$(ARCH)/Kconfig
+randconfig: $(obj)/conf
+	$< -r arch/$(ARCH)/Kconfig
 
-allyesconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -y arch/$(ARCH)/Kconfig
+allyesconfig: $(obj)/conf
+	$< -y arch/$(ARCH)/Kconfig
 
-allnoconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -n arch/$(ARCH)/Kconfig
+allnoconfig: $(obj)/conf
+	$< -n arch/$(ARCH)/Kconfig
 
-allmodconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -m arch/$(ARCH)/Kconfig
+allmodconfig: $(obj)/conf
+	$< -m arch/$(ARCH)/Kconfig
 
-defconfig: scripts/kconfig/conf
-	./scripts/kconfig/conf -d arch/$(ARCH)/Kconfig
+defconfig: $(obj)/conf
+	$< -d arch/$(ARCH)/Kconfig
 
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