kconfig: Allow out of tree building, build under cmake build directory

tools/cmake/kconfig.cmake

@@ -1,7 +1,7 @@
 include(ExternalProject)
 
 macro(kconfig_set_variables)
-  set(MCONF ${IDF_PATH}/tools/kconfig/mconf)
+  set(MCONF kconfig_bin/mconf)
 
   set_default(SDKCONFIG ${PROJECT_PATH}/sdkconfig)
   set(SDKCONFIG_HEADER ${CMAKE_BINARY_DIR}/sdkconfig.h)
@@ -10,19 +10,20 @@ macro(kconfig_set_variables)
   set(ROOT_KCONFIG ${IDF_PATH}/Kconfig)
 endmacro()
 
-# Use the existing Makefile to build mconf when needed
+# Use the existing Makefile to build mconf (out of tree) when needed
 #
-# TODO: replace this with something more Windows-friendly
+# TODO: Find a solution on Windows
 ExternalProject_Add(mconf
   SOURCE_DIR ${IDF_PATH}/tools/kconfig
   CONFIGURE_COMMAND ""
-  BUILD_IN_SOURCE 1
-  BUILD_COMMAND make mconf
-  BUILD_BYPRODUCTS ${MCONF}
+  BINARY_DIR "kconfig_bin"
+  BUILD_COMMAND make -f ${IDF_PATH}/tools/kconfig/Makefile mconf
+  BUILD_BYPRODUCTS "kconfig_bin" ${MCONF}
   INSTALL_COMMAND ""
   EXCLUDE_FROM_ALL 1
   )
 
+
 # Find all Kconfig files for all components
 function(kconfig_process_config)
   file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/include/config")
@@ -65,7 +66,7 @@ function(kconfig_process_config)
                 "COMPONENT_KCONFIGS=${kconfigs}"
                 "COMPONENT_KCONFIGS_PROJBUILD=${kconfigs_projbuild}"
                 "KCONFIG_CONFIG=${SDKCONFIG}"
-                ${IDF_PATH}/tools/kconfig/mconf ${ROOT_KCONFIG}
+                ${MCONF} ${ROOT_KCONFIG}
     VERBATIM
     USES_TERMINAL)
 

tools/kconfig/Makefile

@@ -2,6 +2,10 @@
 # Kernel configuration targets
 # These targets are used from top-level makefile
 
+# SRCDIR is kconfig source dir, allows for out-of-tree builds
+# if building in tree, SRCDIR==build dir
+SRCDIR := $(abspath $(dir $(firstword $(MAKEFILE_LIST))))
+
 PHONY += xconfig gconfig menuconfig config silentoldconfig \
 	localmodconfig localyesconfig clean
 
@@ -156,13 +160,22 @@ help:
 	@echo  '  tinyconfig	  - Configure the tiniest possible kernel'
 
 # lxdialog stuff
-check-lxdialog  := lxdialog/check-lxdialog.sh
+check-lxdialog  := $(SRCDIR)/lxdialog/check-lxdialog.sh
 
 # Use recursively expanded variables so we do not call gcc unless
 # we really need to do so. (Do not call gcc as part of make mrproper)
 CFLAGS += $(shell $(CONFIG_SHELL) $(check-lxdialog) -ccflags) \
                     -DLOCALE -MD
 
+%.o: $(SRCDIR)/%.c
+	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+
+lxdialog/%.o: $(SRCDIR)/lxdialog/%.c
+	$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+
+%.o: %.c
+	$(CC) -I $(SRCDIR) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
+
 # ===========================================================================
 # Shared Makefile for the various kconfig executables:
 # conf:	  Used for defconfig, oldconfig and related targets
@@ -199,9 +212,12 @@ clean-files += $(all-objs) $(all-deps) conf mconf
 # Check that we have the required ncurses stuff installed for lxdialog (menuconfig)
 PHONY += dochecklxdialog
 $(addprefix ,$(lxdialog)): dochecklxdialog
-dochecklxdialog:
+dochecklxdialog: lxdialog
 	$(CONFIG_SHELL) $(check-lxdialog) -check $(CC) $(CFLAGS) $(LOADLIBES_mconf)
 
+lxdialog:
+	mkdir -p lxdialog
+
 always := dochecklxdialog
 
 # Add environment specific flags
@@ -308,7 +324,7 @@ gconf.glade.h: gconf.glade
 	gconf.glade
 
 
-mconf: $(mconf-objs)
+mconf: lxdialog $(mconf-objs)
 	$(CC) -o $@ $(mconf-objs) $(LOADLIBES_mconf)
 
 conf: $(conf-objs)
@@ -316,15 +332,15 @@ conf: $(conf-objs)
 
 zconf.tab.c: zconf.lex.c
 
-zconf.lex.c: zconf.l
-	flex -L -P zconf -o zconf.lex.c zconf.l
+zconf.lex.c: $(SRCDIR)/zconf.l
+	flex -L -P zconf -o zconf.lex.c $<
 
-zconf.hash.c: zconf.gperf
+zconf.hash.c: $(SRCDIR)/zconf.gperf
 # strip CRs on Windows systems where gperf will otherwise barf on them
-	sed -E "s/\\x0D$$//" zconf.gperf | gperf -t --output-file zconf.hash.c -a -C -E -g -k '1,3,$$' -p -t
+	sed -E "s/\\x0D$$//" $< | gperf -t --output-file zconf.hash.c -a -C -E -g -k '1,3,$$' -p -t
 
-zconf.tab.c: zconf.y
-	bison -t -l -p zconf -o zconf.tab.c zconf.y
+zconf.tab.c: $(SRCDIR)/zconf.y
+	bison -t -l -p zconf -o zconf.tab.c $<
 
 clean:
 	rm -f $(clean-files)