[v2,2/4] Makefile: clang: choose GCC_TOOLCHAIN_DIR not on LD

Message ID 20190211193008.24101-2-ndesaulniers@google.com
State Accepted
Commit ad15006cc78459d059af56729c4d9bed7c7fd860
Headers show
Series
  • [v2,1/4] init/Kconfig: add config support for detecting linker
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Commit Message

Nick Desaulniers Feb. 11, 2019, 7:30 p.m.
This causes an issue when trying to build with `make LD=ld.lld` if
ld.lld and the rest of your cross tools aren't in the same directory
(ex. /usr/local/bin) (as is the case for Android's build system), as the
GCC_TOOLCHAIN_DIR then gets set based on `which $(LD)` which will point
where LLVM tools are, not GCC/binutils tools are located.

Instead, select the GCC_TOOLCHAIN_DIR based on another tool provided by
binutils for which LLVM does not provide a substitute for, such as
elfedit.

Fixes commit 785f11aa595b ("kbuild: Add better clang cross build support")

Link: https://github.com/ClangBuiltLinux/linux/issues/341
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

Tested-by: Nathan Chancellor <natechancellor@gmail.com>

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

---
Changes V1->V2:
* add reviewed and tested tags.

 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.20.1.791.gb4d0f1c61a-goog

Comments

Masahiro Yamada Feb. 16, 2019, 3:02 a.m. | #1
On Tue, Feb 12, 2019 at 5:42 AM <ndesaulniers@google.com> wrote:
>

> This causes an issue when trying to build with `make LD=ld.lld` if

> ld.lld and the rest of your cross tools aren't in the same directory

> (ex. /usr/local/bin) (as is the case for Android's build system), as the

> GCC_TOOLCHAIN_DIR then gets set based on `which $(LD)` which will point

> where LLVM tools are, not GCC/binutils tools are located.

>

> Instead, select the GCC_TOOLCHAIN_DIR based on another tool provided by

> binutils for which LLVM does not provide a substitute for, such as

> elfedit.

>

> Fixes commit 785f11aa595b ("kbuild: Add better clang cross build support")

>

> Link: https://github.com/ClangBuiltLinux/linux/issues/341

> Suggested-by: Nathan Chancellor <natechancellor@gmail.com>

> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

> Tested-by: Nathan Chancellor <natechancellor@gmail.com>

> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

> ---


This one looks correct to me.

Applied to linux-kbuild.



> Changes V1->V2:

> * add reviewed and tested tags.

>

>  Makefile | 2 +-

>  1 file changed, 1 insertion(+), 1 deletion(-)

>

> diff --git a/Makefile b/Makefile

> index 86cf35d1d79d..d3b65e96d183 100644

> --- a/Makefile

> +++ b/Makefile

> @@ -492,7 +492,7 @@ endif

>  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 $(LD)))

> +GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))

>  CLANG_FLAGS    += --prefix=$(GCC_TOOLCHAIN_DIR)

>  GCC_TOOLCHAIN  := $(realpath $(GCC_TOOLCHAIN_DIR)/..)

>  endif

> --

> 2.20.1.791.gb4d0f1c61a-goog

>



--
Best Regards
Masahiro Yamada

Patch

diff --git a/Makefile b/Makefile
index 86cf35d1d79d..d3b65e96d183 100644
--- a/Makefile
+++ b/Makefile
@@ -492,7 +492,7 @@  endif
 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 $(LD)))
+GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
 CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif