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/um/Makefile b/arch/um/Makefile
index 989224f21346..18123bf7b649 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -58,14 +58,14 @@ SYS_DIR		:= $(ARCH_DIR)/include/sysdep-$(SUBARCH)
 #
 # These apply to USER_CFLAGS to.
 
-CFLAGS += $(CFLAGS-y) -D__arch_um__ -DSUBARCH=\"$(SUBARCH)\"    \
+KBUILD_CFLAGS += $(CFLAGS-y) -D__arch_um__ -DSUBARCH=\"$(SUBARCH)\"     \
         $(ARCH_INCLUDE) $(MODE_INCLUDE) -Dvmap=kernel_vmap      \
         -Din6addr_loopback=kernel_in6addr_loopback
 
 AFLAGS += $(ARCH_INCLUDE)
 
 USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -D__KERNEL__,,\
-        $(patsubst -I%,,$(CFLAGS)))) $(ARCH_INCLUDE) $(MODE_INCLUDE) \
+        $(patsubst -I%,,$(KBUILD_CFLAGS)))) $(ARCH_INCLUDE) $(MODE_INCLUDE) \
         -D_FILE_OFFSET_BITS=64
 
 include $(srctree)/$(ARCH_DIR)/Makefile-$(SUBARCH)
@@ -75,14 +75,14 @@ include $(srctree)/$(ARCH_DIR)/Makefile-os-$(OS)
 
 # -Derrno=kernel_errno - This turns all kernel references to errno into
 # kernel_errno to separate them from the libc errno.  This allows -fno-common
-# in CFLAGS.  Otherwise, it would cause ld to complain about the two different
+# in KBUILD_CFLAGS.  Otherwise, it would cause ld to complain about the two different
 # errnos.
 # These apply to kernelspace only.
 
 KERNEL_DEFINES = -Derrno=kernel_errno -Dsigprocmask=kernel_sigprocmask \
         -Dmktime=kernel_mktime $(ARCH_KERNEL_DEFINES)
-CFLAGS += $(KERNEL_DEFINES)
-CFLAGS += $(call cc-option,-fno-unit-at-a-time,)
+KBUILD_CFLAGS += $(KERNEL_DEFINES)
+KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time,)
 
 # These are needed for clean and mrproper, since in that case .config is not
 # included; the values here are meaningless