x86/Makefile: remove $(guard) use from $(TARGET).efi target

Following the patch 65d104984c ("x86: fix race to build
arch/x86/efi/relocs-dummy.o"), the error message
  nm: 'efi/relocs-dummy.o': No such file"
started to appear on system which can't build the .efi target. This is
because relocs-dummy.o isn't built anymore.
The error is printed by the evaluation of VIRT_BASE and ALT_BASE which
aren't use anyway.

But, we don't need that file as we don't want to build `$(TARGET).efi'
anyway.  On such system, $(guard) evaluate to the shell builtin ':',
which prevent any of the shell commands in `$(TARGET).efi' from been
executed.

Even if $(guard) is evaluated opon use, it depends on $(XEN_BUILD_PE)
which is evaluated at the assignment. So, we can replace $(guard) in
$(TARGET).efi by having two different rules depending on
$(XEN_BUILD_PE) instead.

The change with this patch is that none of the dependency of
$(TARGET).efi will be built if the linker doesn't support PE
and VIRT_BASE and ALT_BASE don't get evaluated anymore, so nm will not
complain about the missing relocs-dummy.o file anymore.

Since prelink-efi.o isn't built on system that can't build
$(TARGET).efi anymore, we can remove the $(guard) variable everywhere.

Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>

xen/arch/x86/Makefile

@@ -120,20 +120,20 @@ prelink_lto.o: $(ALL_OBJS)
 	$(LD_LTO) -r -o $@ $^
 
 prelink-efi_lto.o: $(ALL_OBJS) efi/runtime.o efi/compat.o
-	$(guard) $(LD_LTO) -r -o $@ $(filter-out %/efi/built_in.o,$^)
+	$(LD_LTO) -r -o $@ $(filter-out %/efi/built_in.o,$^)
 
 # Link it with all the binary objects
 prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink_lto.o
 	$(LD) $(LDFLAGS) -r -o $@ $^
 
 prelink-efi.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) prelink-efi_lto.o efi/boot.init.o
-	$(guard) $(LD) $(LDFLAGS) -r -o $@ $^
+	$(LD) $(LDFLAGS) -r -o $@ $^
 else
 prelink.o: $(ALL_OBJS)
 	$(LD) $(LDFLAGS) -r -o $@ $^
 
 prelink-efi.o: $(ALL_OBJS) efi/boot.init.o efi/runtime.o efi/compat.o
-	$(guard) $(LD) $(LDFLAGS) -r -o $@ $(filter-out %/efi/built_in.o,$^)
+	$(LD) $(LDFLAGS) -r -o $@ $(filter-out %/efi/built_in.o,$^)
 endif
 
 $(TARGET)-syms: prelink.o xen.lds
@@ -178,8 +178,6 @@ CFLAGS-$(XEN_BUILD_EFI) += -DXEN_BUILD_EFI
 
 $(TARGET).efi: VIRT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A VIRT_START$$,,p')
 $(TARGET).efi: ALT_BASE = 0x$(shell $(NM) efi/relocs-dummy.o | sed -n 's, A ALT_START$$,,p')
-# Don't use $(wildcard ...) here - at least make 3.80 expands this too early!
-$(TARGET).efi: guard = $(if $(filter y,$(XEN_BUILD_PE)),,:)
 
 ifneq ($(build_id_linker),)
 ifeq ($(call ld-ver-build-id,$(LD) $(filter -m%,$(EFI_LDFLAGS))),y)
@@ -197,27 +195,31 @@ note_file :=
 endif
 note_file_option ?= $(note_file)
 
+ifeq ($(filter y,$(XEN_BUILD_PE)),y)
 $(TARGET).efi: prelink-efi.o $(note_file) efi.lds efi/relocs-dummy.o efi/mkreloc
 	$(foreach base, $(VIRT_BASE) $(ALT_BASE), \
-	          $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< efi/relocs-dummy.o \
+	          $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< efi/relocs-dummy.o \
 	                $(BASEDIR)/common/symbols-dummy.o $(note_file_option) -o $(@D)/.$(@F).$(base).0 &&) :
-	$(guard) efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).0) >$(@D)/.$(@F).0r.S
-	$(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).0 \
-		| $(guard) $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).0s.S
-	$(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o
+	efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).0) >$(@D)/.$(@F).0r.S
+	$(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).0 \
+		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).0s.S
+	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o
 	$(foreach base, $(VIRT_BASE) $(ALT_BASE), \
-	          $(guard) $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< \
+	          $(LD) $(call EFI_LDFLAGS,$(base)) -T efi.lds -N $< \
 	                $(@D)/.$(@F).0r.o $(@D)/.$(@F).0s.o $(note_file_option) -o $(@D)/.$(@F).$(base).1 &&) :
-	$(guard) efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).1) >$(@D)/.$(@F).1r.S
-	$(guard) $(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).1 \
-		| $(guard) $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).1s.S
-	$(guard) $(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o
-	$(guard) $(LD) $(call EFI_LDFLAGS,$(VIRT_BASE)) -T efi.lds -N $< \
+	efi/mkreloc $(foreach base,$(VIRT_BASE) $(ALT_BASE),$(@D)/.$(@F).$(base).1) >$(@D)/.$(@F).1r.S
+	$(NM) -pa --format=sysv $(@D)/.$(@F).$(VIRT_BASE).1 \
+		| $(BASEDIR)/tools/symbols $(all_symbols) --sysv --sort >$(@D)/.$(@F).1s.S
+	$(MAKE) -f $(BASEDIR)/Rules.mk $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o
+	$(LD) $(call EFI_LDFLAGS,$(VIRT_BASE)) -T efi.lds -N $< \
 	                $(@D)/.$(@F).1r.o $(@D)/.$(@F).1s.o $(note_file_option) -o $@
-	if $(guard) false; then rm -f $@; echo 'EFI support disabled'; \
-	else $(NM) -pa --format=sysv $(@D)/$(@F) \
-		| $(BASEDIR)/tools/symbols --xensyms --sysv --sort >$(@D)/$(@F).map; fi
+	$(NM) -pa --format=sysv $(@D)/$(@F) \
+		| $(BASEDIR)/tools/symbols --xensyms --sysv --sort >$(@D)/$(@F).map
 	rm -f $(@D)/.$(@F).[0-9]* $(@D)/..$(@F).[0-9]*
+else
+$(TARGET).efi: FORCE
+	rm -f $@; echo 'EFI support disabled'
+endif
 
 efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o efi/relocs-dummy.o: $(BASEDIR)/arch/x86/efi/built_in.o
 efi/boot.init.o efi/runtime.o efi/compat.o efi/buildid.o efi/relocs-dummy.o: ;