kbuild: test dead code/data elimination support in Kconfig
This config option should be enabled only when both the compiler and
the linker support necessary flags. Add proper dependencies to Kconfig.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/Makefile b/Makefile
index c4d7b4b..1623b8b 100644
--- a/Makefile
+++ b/Makefile
@@ -790,8 +790,8 @@
endif
ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
-KBUILD_CFLAGS_KERNEL += $(call cc-option,-ffunction-sections,)
-KBUILD_CFLAGS_KERNEL += $(call cc-option,-fdata-sections,)
+KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections
+LDFLAGS_vmlinux += --gc-sections
endif
# arch Makefile may override CC so keep this after arch Makefile is included
@@ -857,10 +857,6 @@
KBUILD_LDFLAGS_MODULE += $(LDFLAGS_BUILD_ID)
LDFLAGS_vmlinux += $(LDFLAGS_BUILD_ID)
-ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
-LDFLAGS_vmlinux += $(call ld-option, --gc-sections,)
-endif
-
ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
LDFLAGS_vmlinux += $(call ld-option, -X,)
endif
diff --git a/init/Kconfig b/init/Kconfig
index 9bd50ba..21b8559 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1085,6 +1085,8 @@
bool "Dead code and data elimination (EXPERIMENTAL)"
depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
depends on EXPERT
+ depends on $(cc-option,-ffunction-sections -fdata-sections)
+ depends on $(ld-option,--gc-sections)
help
Enable this if you want to do dead code and data elimination with
the linker by compiling with -ffunction-sections -fdata-sections,