From 7fd9fd46a459272e641be78c1cc36baab1921fa1 Mon Sep 17 00:00:00 2001 From: Adrian Ratiu Date: Tue, 8 Mar 2022 14:14:28 +0200 Subject: [PATCH] tools: Fix unavoidable GCC call in Clang builds In ChromeOS and Gentoo we catch any unwanted mixed Clang/LLVM and GCC/binutils usage via toolchain wrappers which fail builds. This has revealed that GCC is called unconditionally in Clang configured builds to populate GCC_TOOLCHAIN_DIR. Allow the user to override CLANG_CROSS_FLAGS to avoid the GCC call - in our case we set the var directly in the ebuild recipe. In theory Clang could be able to autodetect these settings so this logic could be removed entirely, but in practice as the commit cebdb7374577 ("tools: Help cross-building with clang") mentions, this does not always work, so giving distributions more control to specify their flags & sysroot is beneficial. Suggested-by: Manoj Gupta Suggested-by: Nathan Chancellor Signed-off-by: Adrian Ratiu Signed-off-by: Daniel Borkmann Acked-by: Nathan Chancellor Cc: Nick Desaulniers Link: https://lore.kernel.org/lkml/87czjk4osi.fsf@ryzen9.i-did-not-set--mail-host-address--so-tickle-me Link: https://lore.kernel.org/bpf/20220308121428.81735-1-adrian.ratiu@collabora.com --- tools/scripts/Makefile.include | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include index 79d102304470..a2335e402145 100644 --- a/tools/scripts/Makefile.include +++ b/tools/scripts/Makefile.include @@ -89,6 +89,9 @@ ifeq ($(CC_NO_CLANG), 1) EXTRA_WARNINGS += -Wstrict-aliasing=3 else ifneq ($(CROSS_COMPILE),) +# Allow userspace to override CLANG_CROSS_FLAGS to specify their own +# sysroots and flags or to avoid the GCC call in pure Clang builds. +ifeq ($(CLANG_CROSS_FLAGS),) CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) ifneq ($(GCC_TOOLCHAIN_DIR),) @@ -96,6 +99,7 @@ CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) endif # GCC_TOOLCHAIN_DIR +endif # CLANG_CROSS_FLAGS CFLAGS += $(CLANG_CROSS_FLAGS) AFLAGS += $(CLANG_CROSS_FLAGS) endif # CROSS_COMPILE -- 2.11.0