[PATCH] kbuild: llvmlinux: Set appropriate compiler-flag for CONFIG_CC_OPTIMIZE_FOR_SIZE

[Sedat Dilek]

Based on a patch of Behan Webster (see [1]).

CLANG (here: v3.7) requires '-Oz' as OptLevel to be set.

A Linux v4.3-rc1 kernel built fine with CONFIG_CC_OPTIMIZE_FOR_SIZE=y
and boots on bare metal.
This is a Ubuntu/precise AMD64 system.

Tested against Linux v4.3-rc1 and a refreshed llvmlinux patchset.

[1] http://git.linuxfoundation.org/?p=llvmlinux.git;a=blob;f=arch/all/patches/smaller.patch

CC: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
---
 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 4249441e535d..a57fb6b39ed7 100644
--- a/Makefile
+++ b/Makefile
@@ -622,7 +622,8 @@ KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
 endif
 
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-KBUILD_CFLAGS	+= -Os $(call cc-disable-warning,maybe-uninitialized,)
+KBUILD_CFLAGS 	+= $(call cc-option,-Oz,-Os)
+KBUILD_CFLAGS	+= $(call cc-disable-warning,maybe-uninitialized,)
 else
 KBUILD_CFLAGS	+= -O2
 endif
-- 
2.5.2

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