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authorMasahiro Yamada <yamada.masahiro@socionext.com>2018-08-22 16:51:09 +0300
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-08-24 02:10:00 +0300
commite85d1d65cd8a9083040e280d172eba762875f8f1 (patch)
tree8038ed2a967ad92502f45a7173bdda15cfed57b7
parentf6f57a46435d7253a52a1a07a58183678ad266a0 (diff)
downloadlinux-e85d1d65cd8a9083040e280d172eba762875f8f1.tar.xz
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>
-rw-r--r--Makefile8
-rw-r--r--init/Kconfig2
2 files changed, 4 insertions, 6 deletions
diff --git a/Makefile b/Makefile
index c4d7b4befac6..1623b8b6e8f5 100644
--- a/Makefile
+++ b/Makefile
@@ -790,8 +790,8 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once)
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 @@ LDFLAGS_BUILD_ID := $(call ld-option, --build-id)
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 9bd50ba8253f..21b855921eaf 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1085,6 +1085,8 @@ config LD_DEAD_CODE_DATA_ELIMINATION
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,