That's safe to do for now. Here's the 0-day failure thread: https://lists.01.org/pipermail/lkp/2017-October/007427.html If I can sort out the issue, I'll submit a v3. On Mon, Oct 30, 2017 at 8:46 AM, Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > 2017-10-30 15:50 GMT+09:00 Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>: >> 2017-10-29 0:00 GMT+09:00 Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>: >>> 2017-10-28 5:13 GMT+09:00 Nick Desaulniers <ndesaulniers@xxxxxxxxxx>: >>>> 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@xxxxxxxxxxxxx> >>>> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> >>>> Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> >>>> --- >>>> Changes since v1: >>>> * base patch off of >>>> git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git >>>> kbuild branch, per Masahiro. >>>> * Use $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) rather than $(CLANG_TRIPLE), per >>>> Masahiro. >>>> >>>> scripts/Kbuild.include | 5 +++-- >>>> 1 file changed, 3 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include >>>> index 064f477dfdca..0f09e4508554 100644 >>>> --- a/scripts/Kbuild.include >>>> +++ b/scripts/Kbuild.include >>>> @@ -228,12 +228,13 @@ cc-if-fullversion = $(shell [ $(cc-fullversion) $(1) $(2) ] && echo $(3) || echo >>>> # cc-ldoption >>>> # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) >>>> cc-ldoption = $(call try-run-cached,\ >>>> - $(CC) $(1) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) >>>> + $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) >>>> >>>> # ld-option >>>> # Usage: LDFLAGS += $(call ld-option, -X) >>>> ld-option = $(call try-run-cached,\ >>>> - $(CC) -x c /dev/null -c -o "$$TMPO" ; $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) >>>> + $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c -o "$$TMPO"; \ >>>> + $(LD) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) >>>> >>>> # ar-option >>>> # Usage: KBUILD_ARFLAGS := $(call ar-option,D) >>>> -- >>>> 2.15.0.rc2.357.g7e34df9404-goog >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >>> Applied to linux-kbuild/kbuild. Thanks! >> >> >> >> I do not know the cause of the problem reported by the 0-day bot, but >> if the problem happens in the following line, >> >> ifeq ($(CONFIG_X86_32),y) >> LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker) >> else >> >> >> >> Does the following solve the issue? (adding $(LDFLAGS)) >> >> ld-option = $(call try-run,\ >> $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c >> -o "$$TMPO"; \ >> $(LD) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) >> >> > > > I dropped this patch for now. > > -- > Best Regards > Masahiro Yamada -- Thanks, ~Nick Desaulniers -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
