kconfig: refactor Makefile to reduce process forks

Refactor Makefile and use read-file macro. For Make >= 4.2, it can read
out a file by using the built-in function.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

scripts/kconfig/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
 /conf
 /[gmnq]conf
-/[gmnq]conf-cfg
+/[gmnq]conf-cflags
+/[gmnq]conf-libs
+/qconf-bin
 /qconf-moc.cc

scripts/kconfig/Makefile

@@ -159,11 +159,12 @@ conf-objs	:= conf.o $(common-objs)
 hostprogs	+= nconf
 nconf-objs	:= nconf.o nconf.gui.o $(common-objs)
 
-HOSTLDLIBS_nconf	= $(shell . $(obj)/nconf-cfg && echo $$libs)
-HOSTCFLAGS_nconf.o	= $(shell . $(obj)/nconf-cfg && echo $$cflags)
-HOSTCFLAGS_nconf.gui.o	= $(shell . $(obj)/nconf-cfg && echo $$cflags)
+HOSTLDLIBS_nconf       = $(call read-file, $(obj)/nconf-libs)
+HOSTCFLAGS_nconf.o     = $(call read-file, $(obj)/nconf-cflags)
+HOSTCFLAGS_nconf.gui.o = $(call read-file, $(obj)/nconf-cflags)
 
-$(obj)/nconf.o $(obj)/nconf.gui.o: $(obj)/nconf-cfg
+$(obj)/nconf: | $(obj)/nconf-libs
+$(obj)/nconf.o $(obj)/nconf.gui.o: | $(obj)/nconf-cflags
 
 # mconf: Used for the menuconfig target based on lxdialog
 hostprogs	+= mconf
@@ -171,27 +172,28 @@ lxdialog	:= $(addprefix lxdialog/, \
 		     checklist.o inputbox.o menubox.o textbox.o util.o yesno.o)
 mconf-objs	:= mconf.o $(lxdialog) $(common-objs)
 
-HOSTLDLIBS_mconf = $(shell . $(obj)/mconf-cfg && echo $$libs)
+HOSTLDLIBS_mconf = $(call read-file, $(obj)/mconf-libs)
 $(foreach f, mconf.o $(lxdialog), \
-  $(eval HOSTCFLAGS_$f = $$(shell . $(obj)/mconf-cfg && echo $$$$cflags)))
+  $(eval HOSTCFLAGS_$f = $$(call read-file, $(obj)/mconf-cflags)))
 
-$(addprefix $(obj)/, mconf.o $(lxdialog)): $(obj)/mconf-cfg
+$(obj)/mconf: | $(obj)/mconf-libs
+$(addprefix $(obj)/, mconf.o $(lxdialog)): | $(obj)/mconf-cflags
 
 # qconf: Used for the xconfig target based on Qt
 hostprogs	+= qconf
 qconf-cxxobjs	:= qconf.o qconf-moc.o
 qconf-objs	:= images.o $(common-objs)
 
-HOSTLDLIBS_qconf	= $(shell . $(obj)/qconf-cfg && echo $$libs)
-HOSTCXXFLAGS_qconf.o	= $(shell . $(obj)/qconf-cfg && echo $$cflags)
-HOSTCXXFLAGS_qconf-moc.o = $(shell . $(obj)/qconf-cfg && echo $$cflags)
-
-$(obj)/qconf.o: $(obj)/qconf-cfg
+HOSTLDLIBS_qconf         = $(call read-file, $(obj)/qconf-libs)
+HOSTCXXFLAGS_qconf.o     = -std=c++11 -fPIC $(call read-file, $(obj)/qconf-cflags)
+HOSTCXXFLAGS_qconf-moc.o = -std=c++11 -fPIC $(call read-file, $(obj)/qconf-cflags)
+$(obj)/qconf: | $(obj)/qconf-libs
+$(obj)/qconf.o $(obj)/qconf-moc.o: | $(obj)/qconf-cflags
 
 quiet_cmd_moc = MOC     $@
-      cmd_moc = $(shell . $(obj)/qconf-cfg && echo $$moc) $< -o $@
+      cmd_moc = $(call read-file, $(obj)/qconf-bin)/moc $< -o $@
 
-$(obj)/qconf-moc.cc: $(src)/qconf.h $(obj)/qconf-cfg FORCE
+$(obj)/qconf-moc.cc: $(src)/qconf.h FORCE | $(obj)/qconf-bin
 	$(call if_changed,moc)
 
 targets += qconf-moc.cc
@@ -200,15 +202,16 @@ targets += qconf-moc.cc
 hostprogs	+= gconf
 gconf-objs	:= gconf.o images.o $(common-objs)
 
-HOSTLDLIBS_gconf    = $(shell . $(obj)/gconf-cfg && echo $$libs)
-HOSTCFLAGS_gconf.o  = $(shell . $(obj)/gconf-cfg && echo $$cflags)
+HOSTLDLIBS_gconf   = $(call read-file, $(obj)/gconf-libs)
+HOSTCFLAGS_gconf.o = $(call read-file, $(obj)/gconf-cflags)
 
-$(obj)/gconf.o: $(obj)/gconf-cfg
+$(obj)/gconf: | $(obj)/gconf-libs
+$(obj)/gconf.o: | $(obj)/gconf-cflags
 
 # check if necessary packages are available, and configure build flags
-filechk_conf_cfg = $(CONFIG_SHELL) $<
+cmd_conf_cfg = $< $(addprefix $(obj)/$*conf-, cflags libs bin)
 
-$(obj)/%conf-cfg: $(src)/%conf-cfg.sh FORCE
-	$(call filechk,conf_cfg)
+$(obj)/%conf-cflags $(obj)/%conf-libs $(obj)/%conf-bin: $(src)/%conf-cfg.sh
+	$(call cmd,conf_cfg)
 
-clean-files += *conf-cfg
+clean-files += *conf-cflags *conf-libs *conf-bin

scripts/kconfig/gconf-cfg.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
+cflags=$1
+libs=$2
+
 PKG="gtk+-2.0 gmodule-2.0 libglade-2.0"
 
 if [ -z "$(command -v ${HOSTPKG_CONFIG})" ]; then
@@ -26,5 +29,5 @@ if ! ${HOSTPKG_CONFIG} --atleast-version=2.0.0 gtk+-2.0; then
 	exit 1
 fi
 
-echo cflags=\"$(${HOSTPKG_CONFIG} --cflags $PKG)\"
-echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG)\"
+${HOSTPKG_CONFIG} --cflags ${PKG} > ${cflags}
+${HOSTPKG_CONFIG} --libs ${PKG} > ${libs}

scripts/kconfig/mconf-cfg.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
+cflags=$1
+libs=$2
+
 PKG="ncursesw"
 PKG2="ncurses"
 
 if [ -n "$(command -v ${HOSTPKG_CONFIG})" ]; then
 	if ${HOSTPKG_CONFIG} --exists $PKG; then
-		echo cflags=\"$(${HOSTPKG_CONFIG} --cflags $PKG)\"
-		echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG)\"
+		${HOSTPKG_CONFIG} --cflags ${PKG} > ${cflags}
+		${HOSTPKG_CONFIG} --libs ${PKG} > ${libs}
 		exit 0
 	fi
 
-	if ${HOSTPKG_CONFIG} --exists $PKG2; then
-		echo cflags=\"$(${HOSTPKG_CONFIG} --cflags $PKG2)\"
-		echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG2)\"
+	if ${HOSTPKG_CONFIG} --exists ${PKG2}; then
+		${HOSTPKG_CONFIG} --cflags ${PKG2} > ${cflags}
+		${HOSTPKG_CONFIG} --libs ${PKG2} > ${libs}
 		exit 0
 	fi
 fi
@@ -22,22 +25,22 @@ fi
 # (Even if it is installed, some distributions such as openSUSE cannot
 # find ncurses by pkg-config.)
 if [ -f /usr/include/ncursesw/ncurses.h ]; then
-	echo cflags=\"-D_GNU_SOURCE -I/usr/include/ncursesw\"
-	echo libs=\"-lncursesw\"
+	echo -D_GNU_SOURCE -I/usr/include/ncursesw > ${cflags}
+	echo -lncursesw > ${libs}
 	exit 0
 fi
 
 if [ -f /usr/include/ncurses/ncurses.h ]; then
-	echo cflags=\"-D_GNU_SOURCE -I/usr/include/ncurses\"
-	echo libs=\"-lncurses\"
+	echo -D_GNU_SOURCE -I/usr/include/ncurses > ${cflags}
+	echo -lncurses > ${libs}
 	exit 0
 fi
 
 # As a final fallback before giving up, check if $HOSTCC knows of a default
 # ncurses installation (e.g. from a vendor-specific sysroot).
 if echo '#include <ncurses.h>' | ${HOSTCC} -E - >/dev/null 2>&1; then
-	echo cflags=\"-D_GNU_SOURCE\"
-	echo libs=\"-lncurses\"
+	echo -D_GNU_SOURCE > ${cflags}
+	echo -lncurses > ${libs}
 	exit 0
 fi
 

scripts/kconfig/nconf-cfg.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
+cflags=$1
+libs=$2
+
 PKG="ncursesw menuw panelw"
 PKG2="ncurses menu panel"
 
 if [ -n "$(command -v ${HOSTPKG_CONFIG})" ]; then
 	if ${HOSTPKG_CONFIG} --exists $PKG; then
-		echo cflags=\"$(${HOSTPKG_CONFIG} --cflags $PKG)\"
-		echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG)\"
+		${HOSTPKG_CONFIG} --cflags ${PKG} > ${cflags}
+		${HOSTPKG_CONFIG} --libs ${PKG} > ${libs}
 		exit 0
 	fi
 
 	if ${HOSTPKG_CONFIG} --exists $PKG2; then
-		echo cflags=\"$(${HOSTPKG_CONFIG} --cflags $PKG2)\"
-		echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG2)\"
+		${HOSTPKG_CONFIG} --cflags ${PKG2} > ${cflags}
+		${HOSTPKG_CONFIG} --libs ${PKG2} > ${libs}
 		exit 0
 	fi
 fi
@@ -22,20 +25,20 @@ fi
 # (Even if it is installed, some distributions such as openSUSE cannot
 # find ncurses by pkg-config.)
 if [ -f /usr/include/ncursesw/ncurses.h ]; then
-	echo cflags=\"-D_GNU_SOURCE -I/usr/include/ncursesw\"
-	echo libs=\"-lncursesw -lmenuw -lpanelw\"
+	echo -D_GNU_SOURCE -I/usr/include/ncursesw > ${cflags}
+	echo -lncursesw -lmenuw -lpanelw > ${libs}
 	exit 0
 fi
 
 if [ -f /usr/include/ncurses/ncurses.h ]; then
-	echo cflags=\"-D_GNU_SOURCE -I/usr/include/ncurses\"
-	echo libs=\"-lncurses -lmenu -lpanel\"
+	echo -D_GNU_SOURCE -I/usr/include/ncurses > ${cflags}
+	echo -lncurses -lmenu -lpanel > ${libs}
 	exit 0
 fi
 
 if [ -f /usr/include/ncurses.h ]; then
-	echo cflags=\"-D_GNU_SOURCE\"
-	echo libs=\"-lncurses -lmenu -lpanel\"
+	echo -D_GNU_SOURCE > ${cflags}
+	echo -lncurses -lmenu -lpanel > ${libs}
 	exit 0
 fi
 

scripts/kconfig/qconf-cfg.sh

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 
+cflags=$1
+libs=$2
+bin=$3
+
 PKG="Qt5Core Qt5Gui Qt5Widgets"
 
 if [ -z "$(command -v ${HOSTPKG_CONFIG})" ]; then
@@ -11,9 +15,9 @@ if [ -z "$(command -v ${HOSTPKG_CONFIG})" ]; then
 fi
 
 if ${HOSTPKG_CONFIG} --exists $PKG; then
-	echo cflags=\"-std=c++11 -fPIC $(${HOSTPKG_CONFIG} --cflags $PKG)\"
-	echo libs=\"$(${HOSTPKG_CONFIG} --libs $PKG)\"
-	echo moc=\"$(${HOSTPKG_CONFIG} --variable=host_bins Qt5Core)/moc\"
+	${HOSTPKG_CONFIG} --cflags ${PKG} > ${cflags}
+	${HOSTPKG_CONFIG} --libs ${PKG} > ${libs}
+	${HOSTPKG_CONFIG} --variable=host_bins Qt5Core > ${bin}
 	exit 0
 fi
 

scripts/remove-stale-files

@@ -47,3 +47,5 @@ rm -f arch/riscv/purgatory/kexec-purgatory.c
 rm -f scripts/extract-cert
 
 rm -f arch/x86/purgatory/kexec-purgatory.c
+
+rm -f scripts/kconfig/[gmnq]conf-cfg