linux-kernel - Re: [PATCH v3 3/6] modpost: Make mod_device

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Message-ID: <CAK7LNAQmQtvB4PfmH4MkRM123wySON6cF6TG79fi0WER1sz4Gw@mail.gmail.com>
Date: Mon, 2 Jun 2025 19:58:41 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Alexey Gladkov <legion@...nel.org>
Cc: Petr Pavlu <petr.pavlu@...e.com>, Luis Chamberlain <mcgrof@...nel.org>, 
	Sami Tolvanen <samitolvanen@...gle.com>, Daniel Gomez <da.gomez@...sung.com>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas.schier@...ux.dev>, 
	linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org, 
	linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v3 3/6] modpost: Make mod_device_table aliases more unique

On Mon, Jun 2, 2025 at 5:07 PM Alexey Gladkov <legion@...nel.org> wrote:
>
> On Mon, Jun 02, 2025 at 04:45:36PM +0900, Masahiro Yamada wrote:
> > On Tue, May 27, 2025 at 6:08 PM Alexey Gladkov <legion@...nel.org> wrote:
> > >
> > > In order to avoid symbol conflicts if they appear in the same binary, a
> > > more unique alias identifier can be generated.
> >
> > Why must this be unique?
> >
> > What problem would happen if the same symbol names
> > appear in MODULE_DEVICE_TABLE()?
>
> Before these patches this was not a problem as non-unique characters are
> in separate object files when the module is compiled separately.
>
> But when the modules are compiled into the kernel, there is a symbol
> conflict when linking vmlinuz. We have modules that export multiple device
> tables from different object files.

This is because the __mod_device_table__* symbols are global, but
I suspect they do not need to be.

Let's test this
https://lore.kernel.org/lkml/20250602105539.392362-1-masahiroy@kernel.org/T/#u




-- 
Best Regards
Masahiro Yamada