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>

1 files changed, 13 insertions, 4 deletions

diff --git a/Makefile.target b/Makefile.target
index af6ac7eaa1..9a6e7dd1b8 100644
--- a/Makefile.target
+++ b/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)
+
+# Now restore obj-y
+obj-y := $(obj-y-save)
 
-all-obj-y = $(obj-y)
-all-obj-y += $(addprefix ../, $(common-obj-y))
+all-obj-y = $(obj-y) $(common-obj-y)
+all-obj-$(CONFIG_SOFTMMU) += $(block-obj-y)
 
 ifndef CONFIG_HAIKU
 LIBS+=-lm