[PATCH 4.1 034/123] kbuild: Allow arch Makefiles to override {cpp,ld,c}flags

From: Greg Kroah-Hartman
Date: Sat Aug 08 2015 - 18:32:45 EST

4.1-stable review patch. If anyone has any objections, please let me know.


From: Michal Marek <mmarek@xxxxxxx>

commit 61754c18752ffb78145671e94f053fb202fff041 upstream.

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@xxxxxxxxxxxx>
Signed-off-by: Michal Marek <mmarek@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

Documentation/kbuild/makefiles.txt | 8 ++++++++
Makefile | 9 +++++----
2 files changed, 13 insertions(+), 4 deletions(-)

--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -952,6 +952,14 @@ When kbuild executes, the following step
$(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
--- a/Makefile
+++ b/Makefile
@@ -783,10 +783,11 @@ endif
include scripts/Makefile.kasan
include scripts/Makefile.extrawarn

-# Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
+# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
+# last assignments

# Use --build-id when available.
LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/