From 5241ab4cf42d3a93b933b55d3d53f43049081fa1 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 29 Jul 2019 18:15:17 +0900 Subject: [PATCH] kbuild: initialize CLANG_FLAGS correctly in the top Makefile CLANG_FLAGS is initialized by the following line: CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) ..., which is run only when CROSS_COMPILE is set. Some build targets (bindeb-pkg etc.) recurse to the top Makefile. When you build the kernel with Clang but without CROSS_COMPILE, the same compiler flags such as -no-integrated-as are accumulated into CLANG_FLAGS. If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', Kbuild will recompile everything needlessly due to the build command change. Fix this by correctly initializing CLANG_FLAGS. Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") Cc: # v5.0+ Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Acked-by: Nick Desaulniers --- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index fa0fbe7851ea..5ee6f6889869 100644 --- a/Makefile +++ b/Makefile @@ -472,6 +472,7 @@ KBUILD_CFLAGS_MODULE := -DMODULE KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds KBUILD_LDFLAGS := GCC_PLUGINS_CFLAGS := +CLANG_FLAGS := export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC export CPP AR NM STRIP OBJCOPY OBJDUMP PAHOLE KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS @@ -519,7 +520,7 @@ endif ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) ifneq ($(CROSS_COMPILE),) -CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) +CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)