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authorNick Desaulniers <ndesaulniers@google.com>2017-11-06 10:47:54 -0800
committerMasahiro Yamada <yamada.masahiro@socionext.com>2017-11-13 22:54:24 +0900
commit86a9df597cdd564d2d29c65897bcad42519e3678 (patch)
treecd57b48ad69e38ff413bec74c03e79f492d87539
parente17c400ae194945eef9d9cae38a321c92c1986fb (diff)
kbuild: fix linker feature test macros when cross compiling with Clang
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>
-rw-r--r--scripts/Kbuild.include5
1 files changed, 3 insertions, 2 deletions
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 064f477dfdca..be1c9d65eaf4 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) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
# ar-option
# Usage: KBUILD_ARFLAGS := $(call ar-option,D)