Messages in this thread Patch in this message | | | From | Nathan Chancellor <> | Subject | [PATCH] arm64: Don't unconditionally add -Wno-psabi to KBUILD_CFLAGS | Date | Fri, 7 Jun 2019 09:12:01 -0700 |
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This is a GCC only option, which warns about ABI changes within GCC, so unconditionally adding breaks Clang with tons of:
warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option]
and link time failures:
ld.lld: error: undefined symbol: __efistub___stack_chk_guard >>> referenced by arm-stub.c:73 (/home/nathan/cbl/linux/drivers/firmware/efi/libstub/arm-stub.c:73) >>> arm-stub.stub.o:(__efistub_install_memreserve_table) in archive ./drivers/firmware/efi/libstub/lib.a
I suspect the link time failure comes from some flags not being added via cc-option, which will always fail when an unknown flag is unconditionally added to KBUILD_CFLAGS because -Werror is added after commit c3f0d0bc5b01 ("kbuild, LLVMLinux: Add -Werror to cc-option to support clang").
$ echo "int main() { return 0; }" | clang -Wno-psabi -o /dev/null -x c - warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option] 1 warning generated.
$ echo $? 0
$ echo "int main() { return 0; }" | clang -Werror -Wno-psabi -o /dev/null -x c - error: unknown warning option '-Wno-psabi' [-Werror,-Wunknown-warning-option]
$ echo $? 1
This side effect is user visible (aside from the inordinate amount of -Wunknown-warning-option and build failure), as some warnings that are normally disabled like -Waddress-of-packed-member or -Wunused-const-variable show up.
Use cc-disable-warning so that it gets disabled for GCC and does nothing for Clang.
Fixes: ebcc5928c5d9 ("arm64: Silence gcc warnings about arch ABI drift") Link: https://github.com/ClangBuiltLinux/linux/issues/511 Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- arch/arm64/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 8fbd583b18e1..e9d2e578cbe6 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -51,7 +51,7 @@ endif KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -KBUILD_CFLAGS += -Wno-psabi +KBUILD_CFLAGS += $(call cc-disable-warning, psabi) KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) -- 2.22.0.rc3
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