[Qemu-devel] [RFC PATCH v3 3/5] Makefile: introduce common-obj-m and block-obj-m for DSO

[Fam Zheng]

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 += -fPIC

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 ruled out in each sub-Makefile.objs with an variable:

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

in the same style with foo.o-cflags and foo.o-libs.

Signed-off-by: Fam Zheng <address@hidden>
---
 Makefile        | 26 ++++++++++++++++++++++++--
 Makefile.objs   |  5 +++++
 Makefile.target |  4 ++++
 configure       |  6 ++++++
 rules.mak       | 16 +++++++++++++++-
 tests/Makefile  |  1 +
 6 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index ef80f0d..658c089 100644
--- a/Makefile
+++ b/Makefile
@@ -125,7 +125,9 @@ 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)
 
@@ -133,7 +135,24 @@ ifneq ($(wildcard config-host.mak),)
 include $(SRC_PATH)/tests/Makefile
 endif
 
-all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all
+# static linked mods are expanded to .o list
+dummy := $(call expand-mod-obj,common-obj-y)
+dummy := $(call expand-mod-obj,block-obj-y)
+
+modules-m = $(patsubst %.o,%$(DSOSUF),$(filter %.o,$(block-obj-m) 
$(common-obj-m))) \
+            $(patsubst %.mo,%$(DSOSUF),$(filter %.mo,$(block-obj-m) 
$(common-obj-m)))
+
+all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all $(modules-m)
+
+# Generate rules for single file modules (%.so: %.o).
+$(foreach o,$(filter %.o,$(block-obj-m) $(common-obj-m)),$(eval \
+       $(patsubst %.o,%.so,$o): $o))
+
+# For multi file modules, dependencies should be listed explicitly in
+# Makefile.objs as
+#     foo.mo-objs := bar.o biz.o
+$(foreach o,$(filter %.mo,$(block-obj-m) $(common-obj-m)),$(eval \
+       $(patsubst %.mo,%.so,$o): $($o-objs)))
 
 vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
 
@@ -251,6 +270,9 @@ 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 '*.so' -type f -exec rm -f {} +
+       find . -name '*.dll' -type f -exec rm -f {} +
+
        rm -f $(TOOLS) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
        rm -Rf .libs
        rm -f qemu-img-cmds.h
diff --git a/Makefile.objs b/Makefile.objs
index efd5b0f..abf59e6 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -19,6 +19,8 @@ block-obj-y += qemu-coroutine.o qemu-coroutine-lock.o 
qemu-coroutine-io.o
 block-obj-y += qemu-coroutine-sleep.o
 block-obj-y += coroutine-$(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
 
 ######################################################################
diff --git a/Makefile.target b/Makefile.target
index 381022d..8d70560 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -150,6 +150,10 @@ include $(SRC_PATH)/Makefile.objs
 obj-base := ..
 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)
+
 all-obj-y = $(obj-y)
 all-obj-y += $(addprefix ../, $(common-obj-y) $(block-obj-y))
 
diff --git a/configure b/configure
index cc3cd4d..c6d4a62 100755
--- a/configure
+++ b/configure
@@ -190,6 +190,8 @@ mingw32="no"
 gcov="no"
 gcov_tool="gcov"
 EXESUF=""
+DSOSUF=".so"
+LDFLAGS_SHARED="-shared"
 prefix="/usr/local"
 mandir="\${prefix}/share/man"
 datadir="\${prefix}/share"
@@ -485,6 +487,7 @@ OpenBSD)
 Darwin)
   bsd="yes"
   darwin="yes"
+  LDFLAGS_SHARED="-bundle"
   if [ "$cpu" = "x86_64" ] ; then
     QEMU_CFLAGS="-arch x86_64 $QEMU_CFLAGS"
     LDFLAGS="-arch x86_64 $LDFLAGS"
@@ -584,6 +587,7 @@ 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 $QEMU_CFLAGS"
@@ -4175,6 +4179,8 @@ echo "LIBTOOLFLAGS=$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
diff --git a/rules.mak b/rules.mak
index 84ed998..b88ac75 100644
--- a/rules.mak
+++ b/rules.mak
@@ -58,6 +58,10 @@ endif
 %.o: %.dtrace
        $(call quiet-command,dtrace -o $@ -G -s $<, "  GEN   $(TARGET_DIR)$@")
 
+%$(DSOSUF): QEMU_CFLAGS += -fPIC
+%$(DSOSUF):
+       $(call quiet-command,$(LD) $^ -o $@ $(LDFLAGS_SHARED),"  LD[M] 
$(TARGET_DIR)$@")
+
 %$(EXESUF): %.o
        $(call LINK,$^)
 
@@ -126,7 +130,11 @@ $(foreach v,$($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
@@ -157,3 +165,9 @@ $(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 = $t)
+endef
diff --git a/tests/Makefile b/tests/Makefile
index 15ef039..0dda538 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -113,6 +113,7 @@ QEMU_CFLAGS += -I$(SRC_PATH)/tests
 nested-vars := block-obj-y
 obj-base := ..
 dummy := $(call unnest-vars)
+dummy := $(call expand-mod-obj,block-obj-y)
 
 tests/test-x86-cpuid.o: QEMU_INCLUDES += -I$(SRC_PATH)/target-i386
 
-- 
1.8.3.1