UPSTREAM: 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>
(cherry picked from commit 785f11aa595bc3d4e74096cbd598ada54ecc0d81)
Signed-off-by: Greg Hackmann <ghackmann@google.com>

Change-Id: I9e4ca1a149bc793b749952f1b5734bbc11777e65
This commit is contained in:
Behan Webster 2017-04-21 11:20:01 -07:00 committed by Greg Hackmann
parent 867697792d
commit 3ef0a0c859

View file

@ -694,6 +694,15 @@ 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_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)