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>

3 files changed, 5 insertions, 5 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