kbuild: Allow arch Makefiles to override {cpp,ld,c}flags
Since commit a1c48bb1 (Makefile: Fix unrecognized cross-compiler command
line options), the arch Makefile is included earlier by the main
Makefile, preventing the arc architecture to set its -O3 compiler
option. Since there might be more use cases for an arch Makefile to
fine-tune the options, add support for ARCH_CPPFLAGS, ARCH_AFLAGS and
ARCH_CFLAGS variables that are appended to the respective kbuild
variables. The user still has the final say via the KCPPFLAGS, KAFLAGS
and KCFLAGS variables.
Reported-by: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Michal Marek <mmarek@suse.com>
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index e63b446..13f888a 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -952,6 +952,14 @@
$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
mode) if this option is supported by $(AR).
+ ARCH_CPPFLAGS, ARCH_AFLAGS, ARCH_CFLAGS Overrides the kbuild defaults
+
+ These variables are appended to the KBUILD_CPPFLAGS,
+ KBUILD_AFLAGS, and KBUILD_CFLAGS, respectively, after the
+ top-level Makefile has set any other flags. This provides a
+ means for an architecture to override the defaults.
+
+
--- 6.2 Add prerequisites to archheaders:
The archheaders: rule is used to generate header files that