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, 4 insertions, 4 deletions

diff --git a/arch/cris/Makefile b/arch/cris/Makefile
index ee114699ef8e..32ef6f3cce06 100644
--- a/arch/cris/Makefile
+++ b/arch/cris/Makefile
@@ -31,16 +31,16 @@ OBJCOPYFLAGS := -O binary -R .note -R .comment -S
 CPPFLAGS_vmlinux.lds = -DDRAM_VIRTUAL_BASE=0x$(CONFIG_ETRAX_DRAM_VIRTUAL_BASE)
 AFLAGS += -mlinux
 
-CFLAGS := $(CFLAGS) -mlinux -march=$(arch-y) -pipe
+KBUILD_CFLAGS += -mlinux -march=$(arch-y) -pipe
 
 ifdef CONFIG_FRAME_POINTER
-CFLAGS := $(subst -fomit-frame-pointer,,$(CFLAGS)) -g
-CFLAGS += -fno-omit-frame-pointer
+KBUILD_CFLAGS := $(subst -fomit-frame-pointer,,$(KBUILD_CFLAGS)) -g
+KBUILD_CFLAGS += -fno-omit-frame-pointer
 endif
 
 head-y := arch/$(ARCH)/$(SARCH)/kernel/head.o
 
-LIBGCC = $(shell $(CC) $(CFLAGS) -print-file-name=libgcc.a)
+LIBGCC = $(shell $(CC) $(KBUILD_CFLAGS) -print-file-name=libgcc.a)
 
 core-y          += arch/$(ARCH)/kernel/ arch/$(ARCH)/mm/
 core-y          += arch/$(ARCH)/$(SARCH)/kernel/ arch/$(ARCH)/$(SARCH)/mm/