From: Behan Webster <behanw@converseincode.com>
Date: Fri, 21 Apr 2017 18:20:01 +0000 (-0700)
Subject: kbuild: Add better clang cross build support
X-Git-Tag: v4.12-rc1~27^2~9
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=785f11aa595bc3d4e74096cbd598ada54ecc0d81;p=platform%2Fkernel%2Flinux-exynos.git

kbuild: Add better clang cross build support

Add cross target to CC if using clang. Also add custom gcc toolchain
path for fallback gcc tools.

Clang will fallback to using things like ld, as, and libgcc if
(respectively) one of the llvm linkers isn't available, the integrated
assembler is turned off, or an appropriately cross-compiled version of
compiler-rt isn't available. To this end, you can specify the path to
this fallback gcc toolchain with GCC_TOOLCHAIN.

Signed-off-by: Behan Webster <behanw@converseincode.com>
Reviewed-by: Jan-Simon Möller <dl9pf@gmx.de>
Reviewed-by: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

diff --git a/Makefile b/Makefile
index f178b9a..88d6072 100644
--- a/Makefile
+++ b/Makefile
@@ -688,6 +688,15 @@ endif
 KBUILD_CFLAGS += $(stackp-flag)
 
 ifeq ($(cc-name),clang)
+ifneq ($(CROSS_COMPILE),)
+CLANG_TARGET	:= -target $(notdir $(CROSS_COMPILE:%-=%))
+GCC_TOOLCHAIN	:= $(realpath $(dir $(shell which $(LD)))/..)
+endif
+ifneq ($(GCC_TOOLCHAIN),)
+CLANG_GCC_TC	:= -gcc-toolchain $(GCC_TOOLCHAIN)
+endif
+KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
+KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)