[XEN PATCH v4 28/32] libs/light: Rework acpi table build targets

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

Currently, a rebuild of libxl will always rebuild for example
"build.o". This is because the target depends on "acpi" which never
exist. So instead we will have "build.o" have as prerequisites targets
that are actually generated by "acpi", that is $(DSDT_FILES-y).

While "dsdt_*.c" isn't really a dependency for "build.o", a side
effect of building that dsdt_*.c is to also generate the "ssdt_*.h"
that "build.o" needs, but I don't want to list all the headers needed
by "build.o" and duplicate the information available in
"libacpi/Makefile" at this time.

Also avoid duplicating the "acpi" target for Arm, and unique one for
both architecture. And move the "acpi" target to be with other targets
rather than in the middle of the source listing. For the same reason,
move the prerequisites listing for both $(DSDT_FILES-y) and "build.o".

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---

Notes:
    v4:
    - new patch

 tools/libs/light/Makefile | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/libs/light/Makefile b/tools/libs/light/Makefile
index 1d5716dbba..4a8b0f7bcf 100644
--- a/tools/libs/light/Makefile
+++ b/tools/libs/light/Makefile
@@ -32,14 +32,10 @@ ACPI_PATH  = $(XEN_ROOT)/tools/libacpi
 DSDT_FILES-$(CONFIG_X86) = dsdt_pvh.c
 ACPI_OBJS  = $(patsubst %.c,%.o,$(DSDT_FILES-y)) build.o static_tables.o
 ACPI_PIC_OBJS = $(patsubst %.o,%.opic,$(ACPI_OBJS))
-$(DSDT_FILES-y) build.o build.opic: acpi
+
 vpath build.c $(ACPI_PATH)/
 vpath static_tables.c $(ACPI_PATH)/
 
-.PHONY: acpi
-acpi:
-       $(MAKE) -C $(ACPI_PATH) ACPI_BUILD_DIR=$(CURDIR) 
DSDT_FILES="$(DSDT_FILES-y)"
-
 OBJS-$(CONFIG_X86) += $(ACPI_OBJS)
 
 CFLAGS += -Wno-format-zero-length -Wmissing-declarations \
@@ -58,8 +54,6 @@ ifeq ($(CONFIG_ARM_64),y)
 DSDT_FILES-y = dsdt_anycpu_arm.c
 OBJS-y += libxl_arm_acpi.o
 OBJS-y += $(DSDT_FILES-y:.c=.o)
-dsdt_anycpu_arm.c:
-       $(MAKE) -C $(ACPI_PATH) ACPI_BUILD_DIR=$(CURDIR) 
DSDT_FILES="$(DSDT_FILES-y)"
 else
 OBJS-$(CONFIG_ARM) += libxl_arm_no_acpi.o
 endif
@@ -191,6 +185,12 @@ all: $(CLIENTS) $(TEST_PROGS) $(AUTOSRCS) $(AUTOINCS)
 
 $(OBJS-y) $(PIC_OBJS) $(SAVE_HELPER_OBJS) $(LIBXL_TEST_OBJS) 
$(TEST_PROG_OBJS): $(AUTOINCS) libxl.api-ok
 
+$(DSDT_FILES-y): acpi
+
+# Depends on the source files generated by the "acpi" target even if "build.o"
+# don't needs them but do need the headers that are also generated by "acpi".
+build.o build.opic: $(DSDT_FILES-y)
+
 libxl.api-ok: check-libxl-api-rules _libxl.api-for-check
        $(PERL) $^
        touch $@
@@ -227,6 +227,10 @@ _libxl_type%.h _libxl_type%_json.h _libxl_type%_private.h 
_libxl_type%.c: libxl_
 $(XEN_INCLUDE)/_%.h: _%.h
        $(call move-if-changed,_$*.h,$(XEN_INCLUDE)/_$*.h)
 
+.PHONY: acpi
+acpi:
+       $(MAKE) -C $(ACPI_PATH) ACPI_BUILD_DIR=$(CURDIR) 
DSDT_FILES="$(DSDT_FILES-y)"
+
 libxenlight_test.so: $(PIC_OBJS) $(LIBXL_TEST_OBJS)
        $(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenlight.so.$(MAJOR) 
$(SHLIB_LDFLAGS) -o $@ $^ $(LDLIBS) $(APPEND_LDFLAGS)
 
-- 
Anthony PERARD