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authorFangrui Song <maskray@google.com>2020-07-21 10:31:23 -0700
committerMasahiro Yamada <masahiroy@kernel.org>2020-07-23 11:29:07 +0900
commitca9b31f6bb9c6aa9b4e5f0792f39a97bbffb8c51 (patch)
treedee5668b628e5dd68cecf71c6f47a7c21523061b
parent20b1be59528295e5c2a8812059b8560753dd8e68 (diff)
downloadlwn-ca9b31f6bb9c6aa9b4e5f0792f39a97bbffb8c51.tar.gz
lwn-ca9b31f6bb9c6aa9b4e5f0792f39a97bbffb8c51.zip
Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang cross compilation
When CROSS_COMPILE is set (e.g. aarch64-linux-gnu-), if $(CROSS_COMPILE)elfedit is found at /usr/bin/aarch64-linux-gnu-elfedit, GCC_TOOLCHAIN_DIR will be set to /usr/bin/. --prefix= will be set to /usr/bin/ and Clang as of 11 will search for both $(prefix)aarch64-linux-gnu-$needle and $(prefix)$needle. GCC searchs for $(prefix)aarch64-linux-gnu/$version/$needle, $(prefix)aarch64-linux-gnu/$needle and $(prefix)$needle. In practice, $(prefix)aarch64-linux-gnu/$needle rarely contains executables. To better model how GCC's -B/--prefix takes in effect in practice, newer Clang (since https://github.com/llvm/llvm-project/commit/3452a0d8c17f7166f479706b293caf6ac76ffd90) only searches for $(prefix)$needle. Currently it will find /usr/bin/as instead of /usr/bin/aarch64-linux-gnu-as. Set --prefix= to $(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) (/usr/bin/aarch64-linux-gnu-) so that newer Clang can find the appropriate cross compiling GNU as (when -no-integrated-as is in effect). Cc: stable@vger.kernel.org Reported-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Fangrui Song <maskray@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1099 Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
-rw-r--r--Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 676f1cfb1d56..9d9d4166c0be 100644
--- a/Makefile
+++ b/Makefile
@@ -567,7 +567,7 @@ ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
ifneq ($(CROSS_COMPILE),)
CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
-CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)
+CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
endif
ifneq ($(GCC_TOOLCHAIN),)