kbuild: enable 'make CFLAGS=...' to add additional options to CC
The variable CFLAGS is a wellknown variable and the usage by
kbuild may result in unexpected behaviour.
On top of that several people over time has asked for a way to
pass in additional flags to gcc.
This patch replace use of CFLAGS with KBUILD_CFLAGS all over the
tree and enabling one to use:
make CFLAGS=...
to specify additional gcc commandline options.
One usecase is when trying to find gcc bugs but other
use cases has been requested too.
Patch was tested on following architectures:
alpha, arm, i386, x86_64, mips, sparc, sparc64, ia64, m68k
Test was simple to do a defconfig build, apply the patch and check
that nothing got rebuild.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
diff --git a/Makefile b/Makefile
index 4e474fa..3bc86c69 100644
--- a/Makefile
+++ b/Makefile
@@ -320,7 +320,7 @@
CPPFLAGS := -D__KERNEL__ $(LINUXINCLUDE)
-CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
+KBUILD_CFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -fno-common \
-Werror-implicit-function-declaration
AFLAGS := -D__ASSEMBLY__
@@ -335,7 +335,7 @@
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
export CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
-export CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
+export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
export AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
# When compiling out-of-tree modules, put MODVERDIR in the module
@@ -492,36 +492,36 @@
all: vmlinux
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-CFLAGS += -Os
+KBUILD_CFLAGS += -Os
else
-CFLAGS += -O2
+KBUILD_CFLAGS += -O2
endif
include $(srctree)/arch/$(ARCH)/Makefile
ifdef CONFIG_FRAME_POINTER
-CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
+KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls
else
-CFLAGS += -fomit-frame-pointer
+KBUILD_CFLAGS += -fomit-frame-pointer
endif
ifdef CONFIG_DEBUG_INFO
-CFLAGS += -g
+KBUILD_CFLAGS += -g
AFLAGS += -gdwarf-2
endif
# Force gcc to behave correct even for buggy distributions
-CFLAGS += $(call cc-option, -fno-stack-protector)
+KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector)
# arch Makefile may override CC so keep this after arch Makefile is included
NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS += $(NOSTDINC_FLAGS)
# warn about C99 declaration after statement
-CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
+KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
# disable pointer signed / unsigned warnings in gcc 4.0
-CFLAGS += $(call cc-option,-Wno-pointer-sign,)
+KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,)
# Use --build-id when available.
LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\