4.4-stable review patch. If anyone has any objections, please let me know.
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From: Nick Desaulniers ndesaulniers@google.com
commit 86a9df597cdd564d2d29c65897bcad42519e3678 upstream.
I was not seeing my linker flags getting added when using ld-option when cross compiling with Clang. Upon investigation, this seems to be due to a difference in how GCC vs Clang handle cross compilation.
GCC is configured at build time to support one backend, that is implicit when compiling. Clang is explicit via the use of `-target <triple>` and ships with all supported backends by default.
GNU Make feature test macros that compile then link will always fail when cross compiling with Clang unless Clang's triple is passed along to the compiler. For example:
$ clang -x c /dev/null -c -o temp.o $ aarch64-linux-android/bin/ld -E temp.o aarch64-linux-android/bin/ld: unknown architecture of input file `temp.o' is incompatible with aarch64 output aarch64-linux-android/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400078 $ echo $? 1
$ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o $ aarch64-linux-android/bin/ld -E temp.o aarch64-linux-android/bin/ld: warning: cannot find entry symbol _start; defaulting to 00000000004002e4 $ echo $? 0
This causes conditional checks that invoke $(CC) without the target triple, then $(LD) on the result, to always fail.
Suggested-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Nick Desaulniers ndesaulniers@google.com Reviewed-by: Matthias Kaehlcke mka@chromium.org Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com [nc: Fix conflicts due to lack of commit 3298b690b21cd in linux-4.4.y Use KBUILD_CFLAGS instead of CC_OPTION_FLAGS because commit d26e94149276f that introduced that variable isn't in 4.4 either] Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- scripts/Kbuild.include | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -147,12 +147,13 @@ cc-ifversion = $(shell [ $(cc-version) $ # cc-ldoption # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) cc-ldoption = $(call try-run,\ - $(CC) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) + $(CC) $(1) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
# ld-option # Usage: LDFLAGS += $(call ld-option, -X) ld-option = $(call try-run,\ - $(CC) -x c /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) + $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -x c /dev/null -c -o "$$TMPO"; \ + $(LD) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
# ar-option # Usage: KBUILD_ARFLAGS := $(call ar-option,D)