Patchwork [RFC,v3,3/5] Makefile: introduce common-obj-m and block-obj-m for DSO

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Submitter Fam Zheng
Date Sept. 10, 2013, 1:02 a.m.
Message ID <1378774978-22602-4-git-send-email-famz@redhat.com>
Download mbox | patch
Permalink /patch/273738/
State New
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Comments

Fam Zheng - Sept. 10, 2013, 1:02 a.m.
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 <famz@redhat.com>
---
 Makefile        | 26 ++++++++++++++++++++++++--
 Makefile.objs   |  5 +++++
 Makefile.target |  4 ++++
 configure       |  6 ++++++
 rules.mak       | 16 +++++++++++++++-
 tests/Makefile  |  1 +
 6 files changed, 55 insertions(+), 3 deletions(-)
Paolo Bonzini - Sept. 10, 2013, 6:45 a.m.
Il 10/09/2013 03:02, Fam Zheng ha scritto:
> -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)))

I agree that this foo.mo-objs variable is homogeneous with how you
handle libraries and cflags.  I like it now.

However, I don't like the many places in which you have to special-case
modules (expand-mod-obj, modules-m, etc.), and the duplication between
Makefile and Makefile.target.

I would prefer if you try doing this patch along the lines I suggested
in my review of v2, using .mo files as a placeholder and then doing the
final link either into the .so or in the executable.  This should remove
the need for at least expand-mod-obj, and probably for more of the
duplicated constructs you have.

In particular, I would like modules-m to be simply "$(block-obj-m)
$(common-obj-m)".

In the medium term, we need to find a way to avoid the duplication:

     block-obj-y = block/
     block-obj-m = block/

Perhaps by introducing a "dirs" variable that automatically triggers
recursion on all nested variables.  But this can be the topic of a
separate patch series, if you prefer.

Paolo

>  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
>  
>
Fam Zheng - Sept. 10, 2013, 9:42 a.m.
On Tue, 09/10 08:45, Paolo Bonzini wrote:
> Il 10/09/2013 03:02, Fam Zheng ha scritto:
> > -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)))
> 
> I agree that this foo.mo-objs variable is homogeneous with how you
> handle libraries and cflags.  I like it now.
> 
> However, I don't like the many places in which you have to special-case
> modules (expand-mod-obj, modules-m, etc.), and the duplication between
> Makefile and Makefile.target.
> 
> I would prefer if you try doing this patch along the lines I suggested
> in my review of v2, using .mo files as a placeholder and then doing the
> final link either into the .so or in the executable.  This should remove
> the need for at least expand-mod-obj, and probably for more of the
> duplicated constructs you have.
> 
OK. I'll try.

> In particular, I would like modules-m to be simply "$(block-obj-m)
> $(common-obj-m)".

There need to be some variable with %.o and %.mo subst to %.so, to become
dependency of target "all".

> 
> In the medium term, we need to find a way to avoid the duplication:
> 
>      block-obj-y = block/
>      block-obj-m = block/
> 
> Perhaps by introducing a "dirs" variable that automatically triggers
> recursion on all nested variables.  But this can be the topic of a
> separate patch series, if you prefer.
> 
Agree but prefer to do it in a separate series.

Thanks,

Fam

> >  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
> >  
> > 
>
Paolo Bonzini - Sept. 10, 2013, 10:01 a.m.
Il 10/09/2013 11:42, Fam Zheng ha scritto:
> On Tue, 09/10 08:45, Paolo Bonzini wrote:
>> Il 10/09/2013 03:02, Fam Zheng ha scritto:
>>> -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)))
>>
>> I agree that this foo.mo-objs variable is homogeneous with how you
>> handle libraries and cflags.  I like it now.
>>
>> However, I don't like the many places in which you have to special-case
>> modules (expand-mod-obj, modules-m, etc.), and the duplication between
>> Makefile and Makefile.target.
>>
>> I would prefer if you try doing this patch along the lines I suggested
>> in my review of v2, using .mo files as a placeholder and then doing the
>> final link either into the .so or in the executable.  This should remove
>> the need for at least expand-mod-obj, and probably for more of the
>> duplicated constructs you have.
>>
> OK. I'll try.
> 
>> In particular, I would like modules-m to be simply "$(block-obj-m)
>> $(common-obj-m)".
> 
> There need to be some variable with %.o and %.mo subst to %.so, to become
> dependency of target "all".

I think you are putting too much weight on %.so, which complicates
things when handling both modular and non-modular builds.  Assuming you
have transformed block-obj-m and common-obj-m to only contain .mo files,
with something like this:

    define add-modules
    $(foreach o, $(filter-out %.o, $($1)), $(eval $o-objs := $o))
    $(eval modules-m += $(patsubst %.o,%.mo,$($1)))
    endif

    dummy := $(call add-modules,block-obj-m)
    dummy := $(call add-modules,common-obj-m)

then building modules can be just a bunch of extra targets:

    ifeq ($(CONFIG_MODULES),y)
    modules: $(patsubst %.mo,%$(DSOSUF),$(modules-m))
    all: modules
    endif

>> In the medium term, we need to find a way to avoid the duplication:
>>
>>      block-obj-y = block/
>>      block-obj-m = block/
>>
>> Perhaps by introducing a "dirs" variable that automatically triggers
>> recursion on all nested variables.  But this can be the topic of a
>> separate patch series, if you prefer.
>>
> Agree but prefer to do it in a separate series.

Sure.

Paolo

Patch

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