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>

1 files changed, 5 insertions, 5 deletions

diff --git a/arch/ppc/Makefile b/arch/ppc/Makefile
index eee6264e8a04..43802e95c892 100644
--- a/arch/ppc/Makefile
+++ b/arch/ppc/Makefile
@@ -24,20 +24,20 @@ LDFLAGS_vmlinux	:= -Ttext $(KERNELLOAD) -Bstatic
 # The -Iarch/$(ARCH)/include is temporary while we are merging
 CPPFLAGS        += -Iarch/$(ARCH) -Iarch/$(ARCH)/include
 AFLAGS          += -Iarch/$(ARCH)
-CFLAGS          += -Iarch/$(ARCH) -msoft-float -pipe \
+KBUILD_CFLAGS   += -Iarch/$(ARCH) -msoft-float -pipe \
                 -ffixed-r2 -mmultiple
 
 # No AltiVec instruction when building kernel
-CFLAGS          += $(call cc-option, -mno-altivec)
+KBUILD_CFLAGS   += $(call cc-option, -mno-altivec)
 
-CPP             = $(CC) -E $(CFLAGS)
+CPP             = $(CC) -E $(KBUILD_CFLAGS)
 # Temporary hack until we have migrated to asm-powerpc
 LINUXINCLUDE    += -Iarch/$(ARCH)/include
 
 CHECKFLAGS      += -D__powerpc__
 
 ifndef CONFIG_FSL_BOOKE
-CFLAGS          += -mstring
+KBUILD_CFLAGS   += -mstring
 endif
 
 cpu-as-$(CONFIG_4xx)            += -Wa,-m405
@@ -46,7 +46,7 @@ cpu-as-$(CONFIG_E500)		+= -Wa,-me500
 cpu-as-$(CONFIG_E200)           += -Wa,-me200
 
 AFLAGS += $(cpu-as-y)
-CFLAGS += $(cpu-as-y)
+KBUILD_CFLAGS += $(cpu-as-y)
 
 # Default to the common case.
 KBUILD_DEFCONFIG := common_defconfig