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/sparc/Makefile b/arch/sparc/Makefile
index f33c3817f014..2ce781a7cbf0 100644
--- a/arch/sparc/Makefile
+++ b/arch/sparc/Makefile
@@ -8,15 +8,15 @@
 #
 
 #
-# Uncomment the first CFLAGS if you are doing kgdb source level
+# Uncomment the first KBUILD_CFLAGS if you are doing kgdb source level
 # debugging of the kernel to get the proper debugging information.
 
 AS              := $(AS) -32
 LDFLAGS         := -m elf32_sparc
 CHECKFLAGS      += -D__sparc__
 
-#CFLAGS := $(CFLAGS) -g -pipe -fcall-used-g5 -fcall-used-g7
-CFLAGS := $(CFLAGS) -m32 -pipe -mno-fpu -fcall-used-g5 -fcall-used-g7
+#KBUILD_CFLAGS += -g -pipe -fcall-used-g5 -fcall-used-g7
+KBUILD_CFLAGS += -m32 -pipe -mno-fpu -fcall-used-g5 -fcall-used-g7
 AFLAGS := $(AFLAGS) -m32
 
 #LDFLAGS_vmlinux = -N -Ttext 0xf0004000