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

From: Michal Marek
Date: Wed Jul 01 2015 - 11:13:16 EST


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

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index 74b6c6d..d2b1c40 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -952,6 +952,14 @@ When kbuild executes, the following steps are followed (roughly):
$(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
diff --git a/Makefile b/Makefile
index 3ba5044..aa0dfbe 100644
--- 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
-KBUILD_CPPFLAGS += $(KCPPFLAGS)
-KBUILD_AFLAGS += $(KAFLAGS)
-KBUILD_CFLAGS += $(KCFLAGS)
+# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
+# last assignments
+KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
+KBUILD_AFLAGS += $(ARCH_AFLAGS) $(KAFLAGS)
+KBUILD_CFLAGS += $(ARCH_CFLAGS) $(KCFLAGS)

# Use --build-id when available.
LDFLAGS_BUILD_ID = $(patsubst -Wl$(comma)%,%,\
--
2.1.4

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