Move generation of config-host.h to Makefile from configure

Use timestamp based appreach to avoid not needed recompilation.
Add it to rules.mak

Many thanks to Paolo Bonzini for helpding the design, and the debug.

Patchworks-ID: 35190
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

4 files changed, 21 insertions, 23 deletions

diff --git a/Makefile b/Makefile
index c5527398d8..144b392ca7 100644
--- a/Makefile
+++ b/Makefile
@@ -29,7 +29,10 @@ else
 DOCS=
 endif
 
-build-all: $(TOOLS) $(DOCS) recurse-all
+SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory)
+
+build-all: config-host.h
+	$(call quiet-command, $(MAKE) $(SUBDIR_MAKEFLAGS) $(TOOLS) $(DOCS) recurse-all,)
 
 config-host.mak: configure
 ifneq ($(wildcard config-host.mak),)
@@ -37,10 +40,12 @@ ifneq ($(wildcard config-host.mak),)
 	@sed -n "/.*Configured with/s/[^:]*: //p" $@ | sh
 endif
 
-SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory)
+config-host.h: config-host.h-timestamp
+config-host.h-timestamp: config-host.mak
+
 SUBDIR_RULES=$(patsubst %,subdir-%, $(TARGET_DIRS))
 
-subdir-%:
+subdir-%: config-host.h
 	$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C $* V="$(V)" TARGET_DIR="$*/" all,)
 
 $(filter %-softmmu,$(SUBDIR_RULES)): libqemu_common.a
@@ -200,7 +205,7 @@ clean:
         done
 
 distclean: clean
-	rm -f config-host.mak config-host.h config-host.ld $(DOCS) qemu-options.texi qemu-img-cmds.texi
+	rm -f config-host.mak config-host.h* config-host.ld $(DOCS) qemu-options.texi qemu-img-cmds.texi
 	rm -f qemu-{doc,tech}.{info,aux,cp,dvi,fn,info,ky,log,pg,toc,tp,vr}
 	for d in $(TARGET_DIRS) libhw32 libhw64 libuser; do \
 	rm -rf $$d || exit 1 ; \
diff --git a/configure b/configure
index ed5d7d6da0..fd3cb240cf 100755
--- a/configure
+++ b/configure
@@ -1800,13 +1800,8 @@ echo "-> Your SDL version is too old - please upgrade to have SDL support"
 fi
 
 config_host_mak="config-host.mak"
-config_host_h="config-host.h"
 config_host_ld="config-host.ld"
 
-#echo "Creating $config_host_mak and $config_host_h"
-
-test -f $config_host_h && mv $config_host_h ${config_host_h}~
-
 echo "# Automatically generated by configure - do not modify" > $config_host_mak
 printf "# Configured with:" >> $config_host_mak
 printf " '%s'" "$0" "$@" >> $config_host_mak
@@ -2064,18 +2059,6 @@ echo "LIBS+=$LIBS" >> $config_host_mak
 echo "LIBS_TOOLS+=$libs_tools" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak
 
-echo "/* Automatically generated by configure - do not modify */" > $config_host_h
-
-/bin/sh $source_path/create_config < $config_host_mak >> $config_host_h
-
-if test -f ${config_host_h}~ ; then
-  if cmp -s $config_host_h ${config_host_h}~ ; then
-    mv ${config_host_h}~ $config_host_h
-  else
-    rm ${config_host_h}~
-  fi
-fi
-
 # generate list of library paths for linker script
 
 $ld --verbose -v 2> /dev/null | grep SEARCH_DIR > ${config_host_ld}
@@ -2474,8 +2457,7 @@ fi
 echo "LDFLAGS+=$ldflags" >> $config_mak
 echo "QEMU_CFLAGS+=$cflags" >> $config_mak
 
-echo "/* Automatically generated by configure - do not modify */" > $config_h
-echo "#include \"../config-host.h\"" >> $config_h
+echo "#include \"../config-host.h\"" > $config_h
 
 /bin/sh $source_path/create_config < $config_mak >> $config_h
 
diff --git a/create_config b/create_config
index 5bc8fb6b41..30d0487e24 100755
--- a/create_config
+++ b/create_config
@@ -1,5 +1,7 @@
 #!/bin/sh
 
+echo "/* Automatically generated by create_config - do not modify */"
+
 while read line; do
 
 case $line in
diff --git a/rules.mak b/rules.mak
index b380903322..ca95351d96 100644
--- a/rules.mak
+++ b/rules.mak
@@ -35,3 +35,12 @@ quiet-command = $(if $(V),$1,$(if $(2),@echo $2 && $1, @$1))
 
 cc-option = $(if $(shell $(CC) $1 $2 -S -o /dev/null -xc /dev/null \
               >/dev/null 2>&1 && echo OK), $2, $3)
+
+# Generate timestamp files for .h include files
+
+%.h: %.h-timestamp
+	@test -f $@ || cp $< $@
+
+%.h-timestamp: %.mak
+	$(call quiet-command, $(SRC_PATH)/create_config < $< > $@, "  GEN   $*.h")
+	@cmp $@ $*.h >/dev/null 2>&1 || cp $@ $*.h