rules.mak: fix $(obj) to a real relative path

Makefile.target includes rule.mak and unnested common-obj-y, then prefix
them with '../', this will ignore object specific QEMU_CFLAGS in subdir
Makefile.objs:

    $(obj)/curl.o: QEMU_CFLAGS += $(CURL_CFLAGS)

Because $(obj) here is './block', instead of '../block'. This doesn't
hurt compiling because we basically build all .o from top Makefile,
before entering Makefile.target, but it will affact arriving per-object
libs support.

The starting point of $(obj) is passed in as argument of unnest-vars, as
well as nested variables, so that different Makefiles can pass in a
right value.

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

Makefile

@@ -122,6 +122,16 @@ defconfig:
 
 ifneq ($(wildcard config-host.mak),)
 include $(SRC_PATH)/Makefile.objs
+endif
+
+dummy := $(call unnest-vars,, \
+                stub-obj-y \
+                util-obj-y \
+                qga-obj-y \
+                block-obj-y \
+                common-obj-y)
+
+ifneq ($(wildcard config-host.mak),)
 include $(SRC_PATH)/tests/Makefile
 endif
 ifeq ($(CONFIG_SMARTCARD_NSS),y)
@@ -130,6 +140,10 @@ endif
 
 all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all
 
+vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
+
+vl.o: QEMU_CFLAGS+=$(SDL_CFLAGS)
+
 config-host.h: config-host.h-timestamp
 config-host.h-timestamp: config-host.mak
 qemu-options.def: $(SRC_PATH)/qemu-options.hx

Makefile.objs

@@ -41,7 +41,7 @@ libcacard-y += libcacard/vcardt.o
 # single QEMU executable should support all CPUs and machines.
 
 ifeq ($(CONFIG_SOFTMMU),y)
-common-obj-y = $(block-obj-y) blockdev.o blockdev-nbd.o block/
+common-obj-y = blockdev.o blockdev-nbd.o block/
 common-obj-y += net/
 common-obj-y += qdev-monitor.o device-hotplug.o
 common-obj-$(CONFIG_WIN32) += os-win32.o
@@ -111,18 +111,3 @@ version-lobj-$(CONFIG_WIN32) += $(BUILD_DIR)/version.lo
 # by libqemuutil.a.  These should be moved to a separate .json schema.
 qga-obj-y = qga/ qapi-types.o qapi-visit.o
 qga-vss-dll-obj-y = qga/
-
-vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
-
-vl.o: QEMU_CFLAGS+=$(SDL_CFLAGS)
-
-QEMU_CFLAGS+=$(GLIB_CFLAGS)
-
-nested-vars += \
-	stub-obj-y \
-	util-obj-y \
-	qga-obj-y \
-	qga-vss-dll-obj-y \
-	block-obj-y \
-	common-obj-y
-dummy := $(call unnest-vars)

Makefile.target

@@ -139,13 +139,22 @@ endif # CONFIG_SOFTMMU
 # Workaround for http://gcc.gnu.org/PR55489, see configure.
 %/translate.o: QEMU_CFLAGS += $(TRANSLATE_OPT_CFLAGS)
 
-nested-vars += obj-y
+dummy := $(call unnest-vars,,obj-y)
 
-# This resolves all nested paths, so it must come last
+# we are making another call to unnest-vars with different vars, protect obj-y,
+# it can be overriden in subdir Makefile.objs
+obj-y-save := $(obj-y)
+
+block-obj-y :=
+common-obj-y :=
 include $(SRC_PATH)/Makefile.objs
+dummy := $(call unnest-vars,..,block-obj-y common-obj-y)
 
-all-obj-y = $(obj-y)
-all-obj-y += $(addprefix ../, $(common-obj-y))
+# Now restore obj-y
+obj-y := $(obj-y-save)
+
+all-obj-y = $(obj-y) $(common-obj-y)
+all-obj-$(CONFIG_SOFTMMU) += $(block-obj-y)
 
 ifndef CONFIG_HAIKU
 LIBS+=-lm

configure

@@ -2360,6 +2360,7 @@ fi
 if $pkg_config --atleast-version=$glib_req_ver gthread-2.0; then
     glib_cflags=`$pkg_config --cflags gthread-2.0`
     glib_libs=`$pkg_config --libs gthread-2.0`
+    CFLAGS="$glib_cflags $CFLAGS"
     LIBS="$glib_libs $LIBS"
     libs_qga="$glib_libs $libs_qga"
 else

rules.mak

@@ -146,9 +146,6 @@ clean: clean-timestamp
 
 # magic to descend into other directories
 
-obj := .
-old-nested-dirs :=
-
 define push-var
 $(eval save-$2-$1 = $(value $1))
 $(eval $1 :=)
@@ -162,9 +159,11 @@ endef
 
 define unnest-dir
 $(foreach var,$(nested-vars),$(call push-var,$(var),$1/))
-$(eval obj := $(obj)/$1)
+$(eval obj-parent-$1 := $(obj))
+$(eval obj := $(if $(obj),$(obj)/$1,$1))
 $(eval include $(SRC_PATH)/$1/Makefile.objs)
-$(eval obj := $(patsubst %/$1,%,$(obj)))
+$(eval obj := $(obj-parent-$1))
+$(eval obj-parent-$1 := )
 $(foreach var,$(nested-vars),$(call pop-var,$(var),$1/))
 endef
 
@@ -179,7 +178,12 @@ $(if $(nested-dirs),
 endef
 
 define unnest-vars
+$(eval obj := $1)
+$(eval nested-vars := $2)
+$(eval old-nested-dirs := )
 $(call unnest-vars-1)
+$(if $1,$(foreach v,$(nested-vars),$(eval \
+	$v := $(addprefix $1/,$($v)))))
 $(foreach var,$(nested-vars),$(eval $(var) := $(filter-out %/, $($(var)))))
 $(shell mkdir -p $(sort $(foreach var,$(nested-vars),$(dir $($(var))))))
 $(foreach var,$(nested-vars), $(eval \