[Qemu-devel] [RFC PATCH v2 3/6] Makefile: introduce common-obj-m and block-obj-m for DSO

[Fam Zheng <famz@redhat.com>]

Add necessary rules and flags for shared object generation.
$(common-obj-m) will include $(block-obj-m), like $(common-obj-y) does
for $(block-obj-y). The new rules introduced here are:

0) For all %.so compiling:

    QEMU_CFLAGS += -shared -fPIC

1) %.o in $(common-obj-m) is compiled to %.o, with "QEMU_CFLAGS +=
-shared -fPIC". 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 ruled out in each sub-Makefile.objs with an variable:

    $(obj)/foo.mo-obj := $(addprefix $(obj)/,bar.o baz.o qux.o)

Notice that $(obj)/ is required for both target and dependency in the
rule. DSO suffix (.so) is configure variable (.dll for Windows).

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 Makefile      | 32 +++++++++++++++++++++++++++++---
 Makefile.objs | 14 +++++++++++++-
 configure     |  3 +++
 rules.mak     | 10 ++++++++++
 4 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index 806946e..cf47ea9 100644
--- a/Makefile
+++ b/Makefile
@@ -56,7 +56,7 @@ Makefile: ;
 configure: ;
 
 .PHONY: all clean cscope distclean dvi html info install install-doc \
-	pdf recurse-all speed test dist
+	pdf recurse-all speed test dist modules
 
 $(call set-vpath, $(SRC_PATH))
 
@@ -121,7 +121,30 @@ 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
+
+mod-obj-m = $(patsubst %.o,%$(DSOSUF),$(filter %.o,$(common-obj-m))) \
+            $(patsubst %.mo,%$(DSOSUF),$(filter %.mo,$(common-obj-m)))
+
+# Generate rules for single file modules (%.so: %.o).
+$(foreach o,$(filter %.o,$(common-obj-m)),$(eval \
+	$(patsubst %.o,%.so,$o): $o ))
+
+# For multi file modules, dependencies should be listed explicitly in
+# Makefile.objs as
+#     $(obj)/foo.mo-obj := $(obj)/bar.o $(obj)/biz.o
+$(foreach o,$(filter %.mo,$(mod-obj-m)),$(eval \
+	$o: $($o-obj)))
+
+%.mo:
+	$(if $(BUILD_DYNAMIC), \
+		$(call quiet-command,$(CC) $(sort $^) -shared -o $@,"  LD[M] $(TARGET_DIR)$@"), \
+		$(call quiet-command,$(AR) rcs $@ $(sort $^),"  AR    $(TARGET_DIR)$@"))
+
+
+modules: $(mod-obj-m)
+modules: BUILD_DYNAMIC = 1
+modules: QEMU_CFLAGS += -shared -fPIC
 
 config-host.h: config-host.h-timestamp
 config-host.h-timestamp: config-host.mak
@@ -155,7 +178,7 @@ subdir-dtc:dtc/libfdt dtc/tests
 dtc/%:
 	mkdir -p $@
 
-$(SUBDIR_RULES): libqemuutil.a libqemustub.a $(common-obj-y)
+$(SUBDIR_RULES): libqemuutil.a libqemustub.a $(common-obj-y) $(common-obj-m)
 
 ROMSUBDIR_RULES=$(patsubst %,romsubdir-%, $(ROMS))
 romsubdir-%:
@@ -235,6 +258,9 @@ clean:
 	rm -f qemu-options.def
 	find . -name '*.[oda]' -type f -exec rm -f {} +
 	find . -name '*.l[oa]' -type f -exec rm -f {} +
+	find . -name '*'$(DSOSUF) -type f -exec rm -f {} +
+	find . -name '*.mo' -type f -exec rm -f {} +
+
 	rm -f $(TOOLS) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
 	rm -Rf .libs
 	rm -f qemu-img-cmds.h
diff --git a/Makefile.objs b/Makefile.objs
index f46a4cd..8984a20 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -19,6 +19,8 @@ block-obj-y += qemu-coroutine.o qemu-coroutine-lock.o qemu-coroutine-io.o
 block-obj-y += qemu-coroutine-sleep.o
 block-obj-y += coroutine-$(CONFIG_COROUTINE_BACKEND).o
 
+block-obj-m = block/
+
 ifeq ($(CONFIG_VIRTIO)$(CONFIG_VIRTFS)$(CONFIG_PCI),yyy)
 # Lots of the fsdev/9pcode is pulled in by vl.c via qemu_fsdev_add.
 # only pull in the actual virtio-9p device if we also enabled virtio.
@@ -83,6 +85,9 @@ common-obj-$(CONFIG_SMARTCARD_NSS) += $(libcacard-y)
 
 common-obj-y += qmp-marshal.o
 common-obj-y += qmp.o hmp.o
+
+common-obj-m = $(block-obj-m)
+
 endif
 
 ######################################################################
@@ -121,5 +126,12 @@ nested-vars += \
 	util-obj-y \
 	qga-obj-y \
 	block-obj-y \
-	common-obj-y
+	block-obj-m \
+	common-obj-y \
+	common-obj-m
+
 dummy := $(call unnest-vars)
+
+# static linked mods are expanded to .o list
+dummy := $(call expand-mod-obj,common-obj-y)
+dummy := $(call expand-mod-obj,block-obj-y)
diff --git a/configure b/configure
index af6b048..75abb87 100755
--- a/configure
+++ b/configure
@@ -190,6 +190,7 @@ mingw32="no"
 gcov="no"
 gcov_tool="gcov"
 EXESUF=""
+DSOSUF=".so"
 prefix="/usr/local"
 mandir="\${prefix}/share/man"
 datadir="\${prefix}/share"
@@ -584,6 +585,7 @@ 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 $QEMU_CFLAGS"
@@ -4175,6 +4177,7 @@ echo "LIBTOOLFLAGS=$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" >> $config_host_mak
 echo "LIBS_QGA+=$libs_qga" >> $config_host_mak
 echo "POD2MAN=$POD2MAN" >> $config_host_mak
 echo "TRANSLATE_OPT_CFLAGS=$TRANSLATE_OPT_CFLAGS" >> $config_host_mak
diff --git a/rules.mak b/rules.mak
index e581d55..0a39499 100644
--- a/rules.mak
+++ b/rules.mak
@@ -58,6 +58,10 @@ endif
 %.o: %.dtrace
 	$(call quiet-command,dtrace -o $@ -G -s $<, "  GEN   $(TARGET_DIR)$@")
 
+%$(DSOSUF): QEMU_CLFAGS += -shared -fPIC
+%$(DSOSUF): %.o
+	$(call quiet-command,$(LD) $< -o $@ -shared,"  LD[M] $(TARGET_DIR)$@")
+
 %$(EXESUF): %.o
 	$(call LINK,$^)
 
@@ -145,3 +149,9 @@ $(shell mkdir -p $(sort $(foreach var,$(nested-vars),$(dir $($(var))))))
 $(foreach var,$(nested-vars), $(eval \
   -include $(addsuffix *.d, $(sort $(dir $($(var)))))))
 endef
+
+define expand-mod-obj
+$(eval pref = $(if $(obj-base),$(obj-base)/,))
+$(eval t = $(foreach o,$($1),$(if $($(pref)$o-obj),$($(pref)$o-obj),$o)))
+$(eval $1 = $t)
+endef
-- 
1.8.3.1