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, 3 insertions, 3 deletions

diff --git a/arch/sparc64/Makefile b/arch/sparc64/Makefile
index cad10c5b83d3..b083dc458ce9 100644
--- a/arch/sparc64/Makefile
+++ b/arch/sparc64/Makefile
@@ -39,17 +39,17 @@ AS		:= $(AS) --undeclared-regs
 endif
 
 ifneq ($(NEW_GCC),y)
-  CFLAGS := $(CFLAGS) -pipe -mno-fpu -mtune=ultrasparc -mmedlow \
+  KBUILD_CFLAGS += -pipe -mno-fpu -mtune=ultrasparc -mmedlow \
             -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
 else
-  CFLAGS := $(CFLAGS) -m64 -pipe -mno-fpu -mcpu=ultrasparc -mcmodel=medlow \
+  KBUILD_CFLAGS += -m64 -pipe -mno-fpu -mcpu=ultrasparc -mcmodel=medlow \
             -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare \
             $(CC_UNDECL)
   AFLAGS += -m64 -mcpu=ultrasparc $(CC_UNDECL)
 endif
 
 ifeq ($(CONFIG_MCOUNT),y)
-  CFLAGS := $(CFLAGS) -pg
+  KBUILD_CFLAGS += -pg
 endif
 
 head-y := arch/sparc64/kernel/head.o arch/sparc64/kernel/init_task.o