linux-kernel - Re: [PATCH v6 00/10] kbuild: yet another series of cleanups (modpost, LTO, MODULE_REL

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Date:   Sun, 22 May 2022 15:49:33 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Sedat Dilek <sedat.dilek@...il.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-modules <linux-modules@...r.kernel.org>,
        clang-built-linux <llvm@...ts.linux.dev>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: Re: [PATCH v6 00/10] kbuild: yet another series of cleanups (modpost,
 LTO, MODULE_REL_CRCS, export.h)

On Sun, May 22, 2022 at 10:45 AM Sedat Dilek <sedat.dilek@...il.com> wrote:
>
> On Fri, May 13, 2022 at 4:31 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > On Fri, May 13, 2022 at 8:42 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
> > >
> > >
> > > This is the third batch of cleanups in this development cycle.
> > >
> >
> >
> > This series is available at
> > git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
> >  lto-cleanup-v6
> >
>
> Hi Masahiro,
>
> I cloned the repository on top of latest Linus Git.
>
> Not able to boot in Quemu - Not able to boot on bare metal.
>
> $ grep module_layout log_quemu-5.18.0-rc7-2-amd64-clang14-lto.txt
> 366:[    2.173265] floppy: disagrees about version of symbol module_layout
> 367:[    2.198746] scsi_common: disagrees about version of symbol module_layout
> 368:[    2.205573] i2c_piix4: disagrees about version of symbol module_layout
> 369:[    2.210610] psmouse: disagrees about version of symbol module_layout
> 370:[    2.225138] scsi_common: disagrees about version of symbol module_layout
> 371:[    2.235536] scsi_common: disagrees about version of symbol module_layout
> 375:Begin: Running /scripts/local-premount ... [    2.298555]
> crc32c_intel: disagrees about version of symbol module_layout
> 376:[    2.303335] crc32c_generic: disagrees about version of symbol
> module_layout
> 377:[    2.306667] libcrc32c: disagrees about version of symbol module_layout
>
> Infos: LLVM-14 + CONFIG_LTO_CLANG_THIN=y
>
> My linux-config and qemu-log are attached.
>


Thanks for your testing.

I was also able to reproduce this issue.


The problematic parts are:

[    2.298555] crc32c_intel: disagrees about version of symbol module_layout
[    2.303335] crc32c_generic: disagrees about version of symbol module_layout
[    2.306667] libcrc32c: disagrees about version of symbol module_layout



When CONFIG_LTO_CLANG_THIN=y,
I cannot see any __crc_* symbols in "nm  vmlinux".

Perhaps, LTO might have discarded all the __crc_* symbols
from vmlinux, but I am still checking the details...



-- 
Best Regards
Masahiro Yamada