rules.mak: introduce DSO rules

Add necessary rules and flags for shared object generation.
The new rules introduced here are:

1) %.o in $(common-obj-m) is compiled to %.o, then linked to %.so.

2) %.mo in $(common-obj-m) is the placeholder for %.so for pattern
matching in Makefile. It's linked to "-shared" with all its dependencies
(multiple *.o) as input. Which means the list of depended objects must
be specified in each sub-Makefile.objs:

    foo.mo-objs := bar.o baz.o qux.o

in the same style with foo.o-cflags and foo.o-libs. The objects here
will be prefixed with "$(obj)/" if it's a subdirectory Makefile.objs.

3) For all files ending up in %.so, the following is added automatically:

    foo.o-cflags += -fPIC -DBUILD_DSO

Also introduce --enable-modules in configure, the option will enable
support of shared object build. Otherwise objects are static linked to
executables.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

.gitignore

@@ -64,6 +64,9 @@ libuser
 *.cp
 *.dvi
 *.exe
+*.dll
+*.so
+*.mo
 *.fn
 *.ky
 *.log

Makefile

@@ -138,7 +138,7 @@ ifeq ($(CONFIG_SMARTCARD_NSS),y)
 include $(SRC_PATH)/libcacard/Makefile
 endif
 
-all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all
+all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all modules
 
 vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
 
@@ -256,6 +256,8 @@ clean:
 	rm -f qemu-options.def
 	find . -name '*.[oda]' -type f -exec rm -f {} +
 	find . -name '*.l[oa]' -type f -exec rm -f {} +
+	find . -name '*$(DSOSUF)' -type f -exec rm -f {} +
+	find . -name '*.mo' -type f -exec rm -f {} +
 	rm -f $(filter-out %.tlb,$(TOOLS)) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
 	rm -f fsdev/*.pod
 	rm -rf .libs */.libs

configure

@@ -205,6 +205,9 @@ mingw32="no"
 gcov="no"
 gcov_tool="gcov"
 EXESUF=""
+DSOSUF=".so"
+LDFLAGS_SHARED="-shared"
+modules="no"
 prefix="/usr/local"
 mandir="\${prefix}/share/man"
 datadir="\${prefix}/share"
@@ -515,6 +518,7 @@ OpenBSD)
 Darwin)
   bsd="yes"
   darwin="yes"
+  LDFLAGS_SHARED="-bundle -undefined dynamic_lookup"
   if [ "$cpu" = "x86_64" ] ; then
     QEMU_CFLAGS="-arch x86_64 $QEMU_CFLAGS"
     LDFLAGS="-arch x86_64 $LDFLAGS"
@@ -608,6 +612,7 @@ fi
 
 if test "$mingw32" = "yes" ; then
   EXESUF=".exe"
+  DSOSUF=".dll"
   QEMU_CFLAGS="-DWIN32_LEAN_AND_MEAN -DWINVER=0x501 $QEMU_CFLAGS"
   # enable C99/POSIX format strings (needs mingw32-runtime 3.15 or later)
   QEMU_CFLAGS="-D__USE_MINGW_ANSI_STDIO=1 $QEMU_CFLAGS"
@@ -674,6 +679,9 @@ for opt do
   ;;
   --disable-debug-info)
   ;;
+  --enable-modules)
+      modules="yes"
+  ;;
   --cpu=*)
   ;;
   --target-list=*) target_list="$optarg"
@@ -1130,6 +1138,7 @@ Advanced options (experts only):
   --sysconfdir=PATH        install config in PATH$confsuffix
   --localstatedir=PATH     install local state in PATH (set at runtime on win32)
   --with-confsuffix=SUFFIX suffix for QEMU data inside datadir and sysconfdir [$confsuffix]
+  --enable-modules         enable modules support
   --enable-debug-tcg       enable TCG debugging
   --disable-debug-tcg      disable TCG debugging (default)
   --enable-debug-info       enable debugging information (default)
@@ -3768,6 +3777,7 @@ echo "python            $python"
 if test "$slirp" = "yes" ; then
     echo "smbd              $smbd"
 fi
+echo "module support    $modules"
 echo "host CPU          $cpu"
 echo "host big endian   $bigendian"
 echo "target list       $target_list"
@@ -4012,6 +4022,9 @@ echo "TARGET_DIRS=$target_list" >> $config_host_mak
 if [ "$docs" = "yes" ] ; then
   echo "BUILD_DOCS=yes" >> $config_host_mak
 fi
+if test "$modules" = "yes"; then
+  echo "CONFIG_MODULES=y" >> $config_host_mak
+fi
 if test "$sdl" = "yes" ; then
   echo "CONFIG_SDL=y" >> $config_host_mak
   echo "SDL_CFLAGS=$sdl_cflags" >> $config_host_mak
@@ -4396,6 +4409,8 @@ echo "LIBTOOLFLAGS=$LIBTOOLFLAGS" >> $config_host_mak
 echo "LIBS+=$LIBS" >> $config_host_mak
 echo "LIBS_TOOLS+=$libs_tools" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak
+echo "DSOSUF=$DSOSUF" >> $config_host_mak
+echo "LDFLAGS_SHARED=$LDFLAGS_SHARED" >> $config_host_mak
 echo "LIBS_QGA+=$libs_qga" >> $config_host_mak
 echo "POD2MAN=$POD2MAN" >> $config_host_mak
 echo "TRANSLATE_OPT_CFLAGS=$TRANSLATE_OPT_CFLAGS" >> $config_host_mak

rules.mak

@@ -22,7 +22,12 @@ QEMU_DGFLAGS += -MMD -MP -MT $@ -MF $(*D)/$(*F).d
 # Same as -I$(SRC_PATH) -I., but for the nested source/object directories
 QEMU_INCLUDES += -I$(<D) -I$(@D)
 
-extract-libs = $(strip $(foreach o,$1,$($o-libs)))
+maybe-add = $(filter-out $1, $2) $1
+extract-libs = $(strip $(sort $(foreach o,$1,$($o-libs)) \
+                  $(foreach o,$(call expand-objs,$1),$($o-libs))))
+expand-objs = $(strip $(sort $(filter %.o,$1)) \
+                  $(foreach o,$(filter %.mo,$1),$($o-objs)) \
+                  $(filter-out %.o %.mo,$1))
 
 %.o: %.c
 	$(call quiet-command,$(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) $($@-cflags) -c -o $@ $<,"  CC    $(TARGET_DIR)$@")
@@ -35,8 +40,8 @@ LINKPROG = $(or $(CXX),$(CC))
 
 ifeq ($(LIBTOOL),)
 LINK = $(call quiet-command,$(LINKPROG) $(QEMU_CFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ \
-       $(sort $(filter %.o, $1)) $(filter-out %.o, $1) $(version-obj-y) \
-       $(call extract-libs,$^) $(LIBS),"  LINK  $(TARGET_DIR)$@")
+       $(call expand-objs,$1) $(version-obj-y) \
+       $(call extract-libs,$1) $(LIBS),"  LINK  $(TARGET_DIR)$@")
 else
 LIBTOOL += $(if $(V),,--quiet)
 %.lo: %.c
@@ -47,12 +52,12 @@ LIBTOOL += $(if $(V),,--quiet)
 	$(call quiet-command,$(LIBTOOL) --mode=compile --tag=CC dtrace -o $@ -G -s $<, " lt GEN $(TARGET_DIR)$@")
 
 LINK = $(call quiet-command,\
-       $(if $(filter %.lo %.la,$^),$(LIBTOOL) --mode=link --tag=CC \
+       $(if $(filter %.lo %.la,$1),$(LIBTOOL) --mode=link --tag=CC \
        )$(LINKPROG) $(QEMU_CFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ \
-       $(sort $(filter %.o, $1)) $(filter-out %.o, $1) \
-       $(if $(filter %.lo %.la,$^),$(version-lobj-y),$(version-obj-y)) \
-       $(if $(filter %.lo %.la,$^),$(LIBTOOLFLAGS)) \
-       $(call extract-libs,$^) $(LIBS),$(if $(filter %.lo %.la,$^),"lt LINK ", "  LINK  ")"$(TARGET_DIR)$@")
+       $(call expand-objs,$1) \
+       $(if $(filter %.lo %.la,$1),$(version-lobj-y),$(version-obj-y)) \
+       $(if $(filter %.lo %.la,$1),$(LIBTOOLFLAGS)) \
+       $(call extract-libs,$1) $(LIBS),$(if $(filter %.lo %.la,$1),"lt LINK ", "  LINK  ")"$(TARGET_DIR)$@")
 endif
 
 %.asm: %.S
@@ -73,6 +78,14 @@ endif
 %.o: %.dtrace
 	$(call quiet-command,dtrace -o $@ -G -s $<, "  GEN   $(TARGET_DIR)$@")
 
+DSO_CFLAGS := -fPIC -DBUILD_DSO
+%$(DSOSUF): LDFLAGS += $(LDFLAGS_SHARED)
+%$(DSOSUF): %.mo libqemustub.a
+	$(call LINK,$^)
+
+.PHONY: modules
+modules:
+
 %$(EXESUF): %.o
 	$(call LINK,$^)
 
@@ -166,7 +179,10 @@ $(foreach v,$($1), \
 		$(eval $v-cflags := )) \
 	$(if $($v-libs), \
 		$(eval $2$v-libs := $($v-libs)) \
-		$(eval $v-libs := )))
+		$(eval $v-libs := )) \
+	$(if $($v-objs), \
+		$(eval $2$v-objs := $(addprefix $2,$($v-objs))) \
+		$(eval $v-objs := )))
 endef
 
 define unnest-dir
@@ -190,6 +206,22 @@ $(if $(nested-dirs),
   $(call unnest-vars-1))
 endef
 
+define process-modules
+$(foreach o,$(filter %.o,$($1)),
+	$(eval $(patsubst %.o,%.mo,$o): $o) \
+	$(eval $(patsubst %.o,%.mo,$o)-objs := $o))
+$(foreach o,$(filter-out $(modules-m), $(patsubst %.o,%.mo,$($1))), \
+    $(eval $o: $($o-objs))
+    $(eval modules-objs-m += $($o-objs))
+    $(eval modules-m += $o)
+    $(eval $o:; $$(call quiet-command,touch $$@,"  GEN   $$(TARGET_DIR)$$@"))
+    $(if $(CONFIG_MODULES),$(eval modules: $(patsubst %.mo,%$(DSOSUF),$o)))) \
+$(eval modules-objs-m := $(sort $(modules-objs-m)))
+$(foreach o,$(modules-objs-m), \
+    $(if $(CONFIG_MODULES),$(eval $o-cflags := $(call maybe-add, $(DSO_CFLAGS), $($o-cflags)))))
+$(eval $(patsubst %-m,%-$(call lnot,$(CONFIG_MODULES)),$1) += $($1))
+endef
+
 define unnest-vars
 $(eval obj := $1)
 $(eval nested-vars := $2)
@@ -201,4 +233,6 @@ $(foreach var,$(nested-vars),$(eval $(var) := $(filter-out %/, $($(var)))))
 $(shell mkdir -p $(sort $(foreach var,$(nested-vars),$(dir $($(var))))))
 $(foreach var,$(nested-vars), $(eval \
   -include $(addsuffix *.d, $(sort $(dir $($(var)))))))
+$(foreach v,$(filter %-m,$(nested-vars)), \
+    $(call process-modules,$v))
 endef