Messages in this thread | | | Subject | Re: [PATCH v2 1/1] x86/Makefile: make -stack-alignment conditional on LLD < 13.0.0 | From | Nathan Chancellor <> | Date | Thu, 10 Jun 2021 14:07:30 -0700 |
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On 6/10/2021 1:58 PM, Tor Vic wrote: > Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped > [1], leading to the following error message when building a LTO kernel > with Clang-13 and LLD-13: > > ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument > '-stack-alignment=8'. Try 'ld.lld --help' > ld.lld: Did you mean '--stackrealign=8'? > > It also appears that the '-code-model' flag is not necessary anymore > starting with LLVM-9 [2]. > > Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. > > These flags were necessary because these flags were not encoded in the > IR properly, so the link would restart optimizations without them. Now > there are properly encoded in the IR, and these flags exposing > implementation details are no longer necessary. > > Changes from v1: > - based on mainline > - provide more information about the flags (Nick) > - use correct tags
Small note for the future, probably not worth resending unless the x86 folks feel it is necessary but these comments belong between the '---' and the stats below so that they do not get included in the final commit message.
> Cc: stable@vger.kernel.org > Link: https://github.com/ClangBuiltLinux/linux/issues/1377 > [1]: https://reviews.llvm.org/D103048 > [2]: https://reviews.llvm.org/D52322 > Signed-off-by: Tor Vic <torvic9@mailbox.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org>
Thank you for the patch!
> --- > arch/x86/Makefile | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 307529417021..cb5e8d39cac1 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -200,8 +200,9 @@ endif > KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) > > ifdef CONFIG_LTO_CLANG > -KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \ > - -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) > +KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +endif > endif > > ifdef CONFIG_X86_NEED_RELOCS >
Cheers, Nathan
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