[PATCH] zap linking-only option from EMBEDDED_EXTRA_CFLAGS

[Jan Beulich <jbeulich@xxxxxxxx>]

While I was suspicious of the compiler issuing a diagnostic about an
unused linking-only option when not doing any linking, I did check this
with a couple of gcc versions only, but not with Clang. (Oddly enough at
least older Clang versions complain about the use of '-nopie' now that
we actually use '-no-pie'.) Filter out the problematic option in all
cases where the variable is consumed for compilation only (which right
now is everywhere).

Fixes: ecd6b9759919 ("Config.mk: correct PIE-related option(s) in 
EMBEDDED_EXTRA_CFLAGS")
Reported-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Arguably with all users of EMBEDDED_EXTRA_CFLAGS using these just for
compiling, the option could be omitted from that variable right away.
But if any compile-and-link-in-one-go use appeared, there would be an
issue.

--- a/tools/firmware/Rules.mk
+++ b/tools/firmware/Rules.mk
@@ -13,7 +13,7 @@ endif
 
 CFLAGS += -Werror
 
-$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
+$(call cc-options-add,CFLAGS,CC,$(filter-out -no-pie,$(EMBEDDED_EXTRA_CFLAGS)))
 
 $(call cc-option-add,CFLAGS,CC,-fcf-protection=none)
 
--- a/tools/tests/x86_emulator/testcase.mk
+++ b/tools/tests/x86_emulator/testcase.mk
@@ -2,7 +2,7 @@ XEN_ROOT = $(CURDIR)/../../..
 CFLAGS :=
 include $(XEN_ROOT)/tools/Rules.mk
 
-$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
+$(call cc-options-add,CFLAGS,CC,$(filter-out -no-pie,$(EMBEDDED_EXTRA_CFLAGS)))
 
 CFLAGS += -fno-builtin -g0 $($(TESTCASE)-cflags)
 
--- a/xen/arch/arm/arch.mk
+++ b/xen/arch/arm/arch.mk
@@ -1,7 +1,7 @@
 ########################################
 # arm-specific definitions
 
-$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
+$(call cc-options-add,CFLAGS,CC,$(filter-out -no-pie,$(EMBEDDED_EXTRA_CFLAGS)))
 $(call cc-option-add,CFLAGS,CC,-Wnested-externs)
 
 # Prevent floating-point variables from creeping into Xen.
--- a/xen/arch/x86/arch.mk
+++ b/xen/arch/x86/arch.mk
@@ -10,7 +10,7 @@ CFLAGS += -DXEN_IMG_OFFSET=$(XEN_IMG_OFF
 # Prevent floating-point variables from creeping into Xen.
 CFLAGS += -msoft-float
 
-$(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
+$(call cc-options-add,CFLAGS,CC,$(filter-out -no-pie,$(EMBEDDED_EXTRA_CFLAGS)))
 $(call cc-option-add,CFLAGS,CC,-Wnested-externs)
 $(call as-option-add,CFLAGS,CC,"vmcall",-DHAVE_AS_VMX)
 $(call as-option-add,CFLAGS,CC,"crc32 %eax$$(comma)%eax",-DHAVE_AS_SSE4_2)
--- a/xen/arch/x86/boot/Makefile
+++ b/xen/arch/x86/boot/Makefile
@@ -12,7 +12,7 @@ endif
 $(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))
+$(call cc-options-add,CFLAGS_x86_32,CC,$(filter-out 
-no-pie,$(EMBEDDED_EXTRA_CFLAGS)))
 CFLAGS_x86_32 += -Werror -fno-builtin -g0 -msoft-float
 ifdef building_out_of_srctree
 CFLAGS_x86_32 += -I$(objtree)/include