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>

4 files changed, 7 insertions, 7 deletions

diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index cb1035f2b7e9..646292aaf1fc 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -50,7 +50,7 @@ HOSTCFLAGS_build.o := $(LINUXINCLUDE)
 # that way we can complain to the user if the CPU is insufficient.
 cflags-i386   := 
 cflags-x86_64 := -m32
-CFLAGS		:= $(LINUXINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
+KBUILD_CFLAGS	:= $(LINUXINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
 		   $(cflags-$(ARCH)) \
 		   -Wall -Wstrict-prototypes \
 		   -march=i386 -mregparm=3 \
@@ -61,7 +61,7 @@ CFLAGS		:= $(LINUXINCLUDE) -g -Os -D_SETUP -D__KERNEL__ \
 			$(call cc-option, -fno-unit-at-a-time)) \
 		   $(call cc-option, -fno-stack-protector) \
 		   $(call cc-option, -mpreferred-stack-boundary=2)
-AFLAGS		:= $(CFLAGS) -D__ASSEMBLY__
+AFLAGS		:= $(KBUILD_CFLAGS) -D__ASSEMBLY__
 
 $(obj)/zImage:  IMAGE_OFFSET := 0x1000
 $(obj)/zImage:  EXTRA_AFLAGS := $(SVGA_MODE) $(RAMDISK)
diff --git a/arch/x86/boot/compressed/Makefile_32 b/arch/x86/boot/compressed/Makefile_32
index 22613c652d22..e43ff7c56e6e 100644
--- a/arch/x86/boot/compressed/Makefile_32
+++ b/arch/x86/boot/compressed/Makefile_32
@@ -11,7 +11,7 @@ EXTRA_AFLAGS	:= -traditional
 LDFLAGS_vmlinux := -T
 hostprogs-y	:= relocs
 
-CFLAGS  := -m32 -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
+KBUILD_CFLAGS  := -m32 -D__KERNEL__ $(LINUX_INCLUDE) -O2 \
 	   -fno-strict-aliasing -fPIC \
 	   $(call cc-option,-ffreestanding) \
 	   $(call cc-option,-fno-stack-protector)
diff --git a/arch/x86/boot/compressed/Makefile_64 b/arch/x86/boot/compressed/Makefile_64
index dc6b3380cc45..3013ad01fe69 100644
--- a/arch/x86/boot/compressed/Makefile_64
+++ b/arch/x86/boot/compressed/Makefile_64
@@ -6,11 +6,11 @@
 
 targets		:= vmlinux vmlinux.bin vmlinux.bin.gz head_64.o misc_64.o piggy.o
 
-CFLAGS := -m64 -D__KERNEL__ $(LINUXINCLUDE) -O2  \
+KBUILD_CFLAGS := -m64 -D__KERNEL__ $(LINUXINCLUDE) -O2  \
 	  -fno-strict-aliasing -fPIC -mcmodel=small \
 	   $(call cc-option, -ffreestanding) \
 	   $(call cc-option, -fno-stack-protector)
-AFLAGS  := $(CFLAGS) -D__ASSEMBLY__
+AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
 LDFLAGS := -m elf_x86_64
 
 LDFLAGS_vmlinux := -T
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 8d03de029d9b..dcd6bb9e0bb3 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -34,8 +34,8 @@ $(obj)/vdso.so: $(src)/vdso.lds $(vobjs) FORCE
 
 CFL := $(PROFILING) -mcmodel=small -fPIC -g0 -O2 -fasynchronous-unwind-tables -m64
 
-$(obj)/vclock_gettime.o: CFLAGS = $(CFL)
-$(obj)/vgetcpu.o: CFLAGS = $(CFL)
+$(obj)/vclock_gettime.o: KBUILD_CFLAGS = $(CFL)
+$(obj)/vgetcpu.o: KBUILD_CFLAGS = $(CFL)
 
 # We also create a special relocatable object that should mirror the symbol
 # table and layout of the linked DSO.  With ld -R we can then refer to