[PATCH 3/3] x86/build: Clean up boot/Makefile

[Andrew Cooper <andrew.cooper3@citrix.com>]

There are no .S intermediate files, so rework in terms of head-bin-objs.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
CC: Anthony PERARD <anthony.perard@citrix.com>

I'm slightly -1 on this, because

  head-bin-objs := $(addprefix $(obj)/,$(head-bin-objs))

is substantial obfuscation which I'd prefer to bin.

Anthony: Why does dropping the targets += line interfere with incremental
builds?  With it gone, *.bin are regenerated unconditionally, but I can't see
what would cause that, nor why the normal dependencies on head.o don't work.
---
 xen/arch/x86/boot/Makefile | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/xen/arch/x86/boot/Makefile b/xen/arch/x86/boot/Makefile
index 294ac2418583..527f3e393037 100644
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -1,16 +1,17 @@
 obj-bin-y += head.o
-head-srcs := cmdline.S reloc.S
 
-nocov-y += $(head-srcs:.S=.o)
-noubsan-y += $(head-srcs:.S=.o)
-targets += $(head-srcs:.S=.o)
+head-bin-objs := cmdline.o reloc.o
 
-head-srcs := $(addprefix $(obj)/, $(head-srcs))
+nocov-y += $(head-bin-objs)
+noubsan-y += $(head-bin-objs)
+targets += $(head-bin-objs)
+
+head-bin-objs := $(addprefix $(obj)/,$(head-bin-objs))
 
 # For .incbin - add $(obj) to the include path and add the dependencies
 # manually as they're not included in .d
 $(obj)/head.o: AFLAGS-y += -Wa$(comma)-I$(obj)
-$(obj)/head.o: $(head-srcs:.S=.bin)
+$(obj)/head.o: $(head-bin-objs:.o=.bin)
 
 CFLAGS_x86_32 := $(subst -m64,-m32 -march=i686,$(XEN_TREEWIDE_CFLAGS))
 $(call cc-options-add,CFLAGS_x86_32,CC,$(EMBEDDED_EXTRA_CFLAGS))
@@ -18,8 +19,8 @@ CFLAGS_x86_32 += -Werror -fno-builtin -g0 -msoft-float
 CFLAGS_x86_32 += -I$(srctree)/include
 
 # override for 32bit binaries
-$(head-srcs:.S=.o): CFLAGS_stack_boundary :=
-$(head-srcs:.S=.o): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic
+$(head-bin-objs): CFLAGS_stack_boundary :=
+$(head-bin-objs): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic
 
 %.bin: %.lnk
 	$(OBJCOPY) -j .text -O binary $< $@
@@ -27,4 +28,4 @@ $(head-srcs:.S=.o): XEN_CFLAGS := $(CFLAGS_x86_32) -fpic
 %.lnk: %.o $(src)/build32.lds
 	$(LD) $(subst x86_64,i386,$(LDFLAGS_DIRECT)) -N -T $(filter %.lds,$^) -o $@ $<
 
-clean-files := cmdline.S reloc.S *.lnk *.bin
+clean-files := *.lnk *.bin
-- 
2.11.0