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authorAdrian Ratiu <adrian.ratiu@collabora.com>2022-03-08 14:14:28 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2022-03-08 23:36:37 +0100
commit7fd9fd46a459272e641be78c1cc36baab1921fa1 (patch)
tree77c749933c7d6d7c6740953128e2e257e5f0cc8a /tools/scripts/Makefile.include
parentd23a8720327d33616f584d76c80824bfa4699be6 (diff)
downloadlinux-7fd9fd46a459272e641be78c1cc36baab1921fa1.tar.bz2
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 <manojgupta@chromium.com> Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> 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
Diffstat (limited to 'tools/scripts/Makefile.include')
-rw-r--r--tools/scripts/Makefile.include4
1 files changed, 4 insertions, 0 deletions
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