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/m32r/Makefile b/arch/m32r/Makefile
index 60e12f312654..c80618ab60ea 100644
--- a/arch/m32r/Makefile
+++ b/arch/m32r/Makefile
@@ -9,7 +9,7 @@ LDFLAGS		:=
 OBJCOPYFLAGS    := -O binary -R .note -R .comment -S
 LDFLAGS_vmlinux :=
 
-CFLAGS += -pipe -fno-schedule-insns
+KBUILD_CFLAGS += -pipe -fno-schedule-insns
 CFLAGS_KERNEL += -mmodel=medium
 CFLAGS_MODULE += -mmodel=large
 
@@ -24,14 +24,14 @@ endif
 cflags-$(CONFIG_ISA_M32R)       += -DNO_FPU
 aflags-$(CONFIG_ISA_M32R)       += -DNO_FPU -O2 -Wa,-no-bitinst
 
-CFLAGS += $(cflags-y)
+KBUILD_CFLAGS += $(cflags-y)
 AFLAGS += $(aflags-y)
 
 CHECKFLAGS      += -D__m32r__ -D__BIG_ENDIAN__=1
 
 head-y  := arch/m32r/kernel/head.o arch/m32r/kernel/init_task.o
 
-LIBGCC  := $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
+LIBGCC  := $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
 
 libs-y  += arch/m32r/lib/ $(LIBGCC)
 core-y  += arch/m32r/kernel/    \