module: implement module loading

This patch adds loading, stamp checking and initialization of modules.

The init function of dynamic module is no longer directly called as
__attribute__((constructor)) in static linked version, it is called
only after passed the checking of presense of stamp symbol:

    qemu_stamp_$RELEASEHASH

where $RELEASEHASH is generated by hashing version strings and content
of configure script.

With this, modules built from a different tree/version/configure will
not be loaded.

The module loading code requires gmodule-2.0.

Modules are searched under
 - CONFIG_MODDIR
 - executable folder (to allow running qemu-{img,io} in the build
   directory)
 - ../ of executable folder (to allow running system emulator in the
   build directory)

Modules are linked under their subdir respectively, then copied to top
level of build directory for above convinience, e.g.:
    $(BUILD_DIR)/block/curl.so -> $(BUILD_DIR)/block-curl.so

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

1 files changed, 3 insertions, 0 deletions

diff --git a/rules.mak b/rules.mak
index 0abf3d1f36..9dda9f760f 100644
--- a/rules.mak
+++ b/rules.mak
@@ -82,6 +82,8 @@ DSO_CFLAGS := -fPIC -DBUILD_DSO
 %$(DSOSUF): LDFLAGS += $(LDFLAGS_SHARED)
 %$(DSOSUF): %.mo libqemustub.a
 	$(call LINK,$^)
+	@# Copy to build root so modules can be loaded when program started without install
+	$(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@), "  CP    $(subst /,-,$@)"))
 
 .PHONY: modules
 modules:
@@ -211,6 +213,7 @@ $(foreach o,$(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-objs += module-common.o)
     $(eval $o: $($o-objs))
     $(eval modules-objs-m += $($o-objs))
     $(eval modules-m += $o)