build(makefile): add helper to detect linker options

This is a small helper to check for possible linker options. If the
linker supports the requested option it is returned and if not nothing
will be returned, e.g.:

  TF_LDFLAGS += $(call ld_option, --no-warn-rwx-segments)

can be called unconditional.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Change-Id: I236800852ece49948ff53a0b91fddba53c8f0f95

diff --git a/make_helpers/build_macros.mk b/make_helpers/build_macros.mk
index 4815efa74396c841aeb6699b51e58ecb2f6d7084..89f43f2f3308d8e0b87aababa6a8f8015e85f738 100644 (file)
--- a/make_helpers/build_macros.mk
+++ b/make_helpers/build_macros.mk
@@ -87,6 +87,12 @@ define assert_numerics
     $(foreach num,$1,$(eval $(call assert_numeric,$(num))))
 endef
 
+# Convenience function to check for a given linker option. An call to
+# $(call ld_option, --no-XYZ) will return --no-XYZ if supported by the linker
+define ld_option
+       $(shell if $(LD) $(1) -v >/dev/null 2>&1; then echo $(1); fi )
+endef
+
 # CREATE_SEQ is a recursive function to create sequence of numbers from 1 to
 # $(2) and assign the sequence to $(1)
 define CREATE_SEQ