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

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Other than you changing the commit comment, this *is* my patch.

I haven't upstreamed this patch yet because we are still characterizing its effects on other architectures.

Clang certainly doesn't require -Oz to be used to be able to boot for arm nor arm64. So the commit message isn't correct either.

NAK

Behan

On 09/14/15 21:19, Sedat Dilek wrote:
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


--
Behan Webster
behanw@xxxxxxxxxxxxxxxxxx

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