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/s390/Makefile b/arch/s390/Makefile
index 143ed8e154af..62a0da42c7fd 100644
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -15,7 +15,7 @@
 
 ifndef CONFIG_64BIT
 LDFLAGS         := -m elf_s390
-CFLAGS          += -m31
+KBUILD_CFLAGS   += -m31
 AFLAGS          += -m31
 UTS_MACHINE     := s390
 STACK_SIZE      := 8192
@@ -23,7 +23,7 @@ CHECKFLAGS	+= -D__s390__ -msize-long
 else
 LDFLAGS         := -m elf64_s390
 MODFLAGS        += -fpic -D__PIC__
-CFLAGS          += -m64
+KBUILD_CFLAGS   += -m64
 AFLAGS          += -m64
 UTS_MACHINE     := s390x
 STACK_SIZE      := 16384
@@ -77,8 +77,8 @@ cflags-$(CONFIG_WARN_STACK) += -mwarn-dynamicstack
 cflags-$(CONFIG_WARN_STACK) += -mwarn-framesize=$(CONFIG_WARN_STACK_SIZE)
 endif
 
-CFLAGS          += -mbackchain -msoft-float $(cflags-y)
-CFLAGS          += -pipe -fno-strength-reduce -Wno-sign-compare 
+KBUILD_CFLAGS   += -mbackchain -msoft-float $(cflags-y)
+KBUILD_CFLAGS   += -pipe -fno-strength-reduce -Wno-sign-compare
 AFLAGS          += $(aflags-y)
 
 OBJCOPYFLAGS    := -O binary