linux-kernel - Re: [PATCH v3] kbuild: check uniqueness of module names

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Message-ID: <CAK7LNARp5n+tL+m9HCysJXt==5fnpH21DDoS2ruuW_6r6BJUDQ@mail.gmail.com>
Date:   Mon, 20 May 2019 12:59:49 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>, Jessica Yu <jeyu@...nel.org>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Michael Schmitz <schmitzmic@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Rusty Russell <rusty@...tcorp.com.au>,
        Kees Cook <keescook@...omium.org>,
        Bernd Petrovitsch <bernd@...rovitsch.priv.at>,
        Alexander Kapshuk <alexander.kapshuk@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] kbuild: check uniqueness of module names

On Mon, May 20, 2019 at 8:52 AM Stephen Rothwell <sfr@...b.auug.org.au> wrote:
>
> Hi Masahiro,
>
> On Sat, 18 May 2019 01:07:15 +0900 Masahiro Yamada <yamada.masahiro@...ionext.com> wrote:
> >
> > It checks not only real modules, but also built-in modules (i.e.
> > controlled by tristate CONFIG option, but currently compiled with =y).
> > Non-unique names for built-in modules also cause problems because
> > /sys/modules/ would fall over.
> >
> > I tested allmodconfig on the latest kernel, and it detected the
> > following:
>
> A powerpc ppc64_defconfig produces:
>
> warning: same basename if the following are built as modules:
>   arch/powerpc/platforms/powermac/nvram.ko
>   drivers/char/nvram.ko
>
> Which is a false positive since
> arch/powerpc/platforms/powermac/Makefile has
>
> # CONFIG_NVRAM is an arch. independent tristate symbol, for pmac32 we really
> # need this to be a bool.  Cheat here and pretend CONFIG_NVRAM=m is really
> # CONFIG_NVRAM=y
> obj-$(CONFIG_NVRAM:m=y)         += nvram.o
>
> Which means that this nvram.o will never be built as a module.
> --
> Cheers,
> Stephen Rothwell


BTW, arm64 defconfig also produces a false positive:

warning: same basename if the following are built as modules:
  arch/arm64/lib/crc32.ko
  lib/crc32.ko

CONFIG_CRC32 is a tristate option, but ARM64 selects CRC32.
So, CRC32 is always =y.


We must stop checking modules.builtin soon.
Sorry about noises.




-- 
Best Regards
Masahiro Yamada