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From: Nathan Chancellor <natechancellor@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	linux-mips@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Dmitry Golovin <dima@golovin.in>,
	Sedat Dilek <sedat.dilek@gmail.com>
Subject: Re: [PATCH 2/2] MIPS: VDSO: Do not disable VDSO when linking with ld.lld
Date: Sun, 19 Apr 2020 13:05:58 -0700	[thread overview]
Message-ID: <20200419200558.GA13017@Ryzen-7-3700X.localdomain> (raw)
In-Reply-To: <CAK7LNAS7QHB3GuBeLDh66OHbYRMzmNQNwiueU7jH1i7v0UTAAQ@mail.gmail.com>

Hi Masahiro,

On Mon, Apr 20, 2020 at 04:32:20AM +0900, Masahiro Yamada wrote:
> On Mon, Apr 20, 2020 at 3:17 AM Nathan Chancellor
> <natechancellor@gmail.com> wrote:
> >
> > On Sun, Apr 19, 2020 at 11:04:45AM -0700, Nathan Chancellor wrote:
> > > Currently, when linking with ld.lld, this warning pops up:
> > >
> > >     arch/mips/vdso/Makefile:70: MIPS VDSO requires binutils >= 2.25
> > >
> > > ld-ifversion calls ld-version, which calls scripts/ld-version.sh, which
> > > is specific to GNU ld. ld.lld has a completely different versioning
> > > scheme (as it follows LLVM's versioning) and it does not have the issue
> > > mentioned in the comment above this block so it should not be subjected
> > > to this check.
> > >
> > > With this patch, the VDSO successfully links and shows P_MIPS_PC32 in
> > > vgettimeofday.o.
> > >
> > > $ llvm-objdump -Dr arch/mips/vdso/vgettimeofday.o | grep R_MIPS_PC32
> > >                       00000024:  R_MIPS_PC32  _start
> > >                       000000b0:  R_MIPS_PC32  _start
> > >                       000002bc:  R_MIPS_PC32  _start
> > >                       0000036c:  R_MIPS_PC32  _start
> > >                       00000468:  R_MIPS_PC32  _start
> > >
> > > Link: https://github.com/ClangBuiltLinux/linux/issues/785
> > > Link: https://github.com/llvm/llvm-project/commit/e364e2e9ce50c12eb2bf093560e1a1a8544d455a
> > > Reported-by: Dmitry Golovin <dima@golovin.in>
> > > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> > > ---
> > >  arch/mips/vdso/Makefile | 8 +++++---
> > >  1 file changed, 5 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/arch/mips/vdso/Makefile b/arch/mips/vdso/Makefile
> > > index d7fe8408603e..f99e583d14a1 100644
> > > --- a/arch/mips/vdso/Makefile
> > > +++ b/arch/mips/vdso/Makefile
> > > @@ -65,9 +65,11 @@ DISABLE_VDSO := n
> > >  # the comments on that file.
> > >  #
> > >  ifndef CONFIG_CPU_MIPSR6
> > > -  ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
> > > -    $(warning MIPS VDSO requires binutils >= 2.25)
> > > -    DISABLE_VDSO := y
> > > +  ifndef CONFIG_LD_IS_LLD
> > > +    ifeq ($(call ld-ifversion, -lt, 225000000, y),y)
> > > +      $(warning MIPS VDSO requires binutils >= 2.25)
> > > +      DISABLE_VDSO := y
> > > +    endif
> > >    endif
> > >  endif
> > >
> > > --
> > > 2.26.1
> > >
> >
> > Hmmm, I still see this warning when first runing make <config>... I
> > assume because this Makefile gets parsed before Kconfig runs.
> 
> 
> I do not see the warning for 'make <config>'.
> 
> Could you tell me how to reproduce it?
> 
> 
> For cleaning, indeed, i see the warning.
> 
> 
> $ make ARCH=mips  LLVM=1 clean
> arch/mips/vdso/Makefile:70: MIPS VDSO requires binutils >= 2.25

This is enough. I think I figured out how to avoid it, I'll be sending
out v2 shortly, I'd appreciate any comments that you have.

> >
> > Perhaps it would be better to check if ld-version is 0 (since that means
> > we are not using GNU ld):
> >
> > ifneq ($(call ld-ifversion, -eq, 0, y),y)
> >
> > I am open to suggestions though.
> >
> > Cheers,
> > Nathan
> >
> > --
> > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20200419181715.GA36234%40ubuntu-s3-xlarge-x86.
> 
> 
> 
> -- 
> Best Regards
> Masahiro Yamada
> 

Cheers,
Nathan

  reply	other threads:[~2020-04-19 20:06 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-19 18:04 [PATCH 1/2] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-19 18:04 ` [PATCH 2/2] MIPS: VDSO: Do not disable VDSO when linking with ld.lld Nathan Chancellor
2020-04-19 18:17   ` Nathan Chancellor
2020-04-19 19:32     ` Masahiro Yamada
2020-04-19 20:05       ` Nathan Chancellor [this message]
2020-04-19 20:21 ` [PATCH v2 1/3] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-19 20:21   ` [PATCH v2 2/3] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-20  9:53     ` Sedat Dilek
2020-04-21  2:42       ` Nathan Chancellor
2020-04-23 14:41         ` Masahiro Yamada
2020-04-19 20:21   ` [PATCH v2 3/3] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-23 14:38   ` [PATCH v2 1/3] kbuild: add CONFIG_LD_IS_LLD Masahiro Yamada
2020-04-23 17:18   ` [PATCH v3 1/4] " Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 2/4] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 3/4] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO Nathan Chancellor
2020-04-26 16:27       ` Thomas Bogendoerfer
2020-04-27  2:08         ` Nathan Chancellor
2020-04-27 16:22           ` Maciej W. Rozycki
2020-04-27 23:24             ` Nathan Chancellor
2020-04-29 17:46               ` Maciej W. Rozycki
2020-04-30  3:14                 ` Nathan Chancellor
2020-04-28  2:17         ` Nathan Chancellor
2020-04-23 17:18     ` [PATCH v3 4/4] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-28 22:14     ` [PATCH v5 0/5] Allow ld.lld to link the MIPS VDSO Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 1/5] kbuild: add CONFIG_LD_IS_LLD Nathan Chancellor
2020-04-29  7:13         ` Sedat Dilek
2020-04-30  3:05           ` Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 2/5] MIPS: VDSO: Move disabling the VDSO logic to Kconfig Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 3/5] MIPS: Unconditionally specify '-EB' or '-EL' Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 4/5] MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO Nathan Chancellor
2020-04-28 22:54         ` Fangrui Song
2020-04-29  0:44           ` Nathan Chancellor
2020-05-02 13:34           ` Maciej W. Rozycki
2020-05-02 13:50         ` Maciej W. Rozycki
2020-05-02 15:49           ` Nathan Chancellor
2020-04-28 22:14       ` [PATCH v4 5/5] MIPS: VDSO: Allow ld.lld to link the VDSO Nathan Chancellor
2020-04-29  7:04       ` [PATCH v5 0/5] Allow ld.lld to link the MIPS VDSO Sedat Dilek
2020-04-30  3:06         ` Nathan Chancellor
2020-05-12  8:05       ` Thomas Bogendoerfer
2020-05-12  8:28         ` Nathan Chancellor
2020-05-13 11:18           ` Thomas Bogendoerfer

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