linux-kernel - Re: [PATCH] sound/oss/dmasound: fix build when some drivers are =m and others are =y

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Message-ID: <588b3e9e-df03-8bd6-b36e-b88212e01e3f@infradead.org>
Date:   Thu, 18 Nov 2021 18:33:04 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kernel test robot <lkp@...el.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>
Subject: Re: [PATCH] sound/oss/dmasound: fix build when some drivers are =m
 and others are =y

On 11/17/21 10:50 PM, Arnd Bergmann wrote:
> On Thu, Nov 18, 2021 at 7:21 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>>
>> When CONFIG_DMASOUND_ATARI=y and CONFIG_DMASOUND_Q40=m,
>> dmasound_atari.o is built first (listed first in the Makefile),
>> so dmasound_core.o is built as builtin, not for use by loadable
>> modules. Then dmasound_q40.o is built and linked with the
>> already-built dmasound_core.o, but the latter does not support
>> use by loadable modules. This causes the missing symbol to be
>> undefined.
>>
>> Fixes this build error:
>> ERROR: modpost: "dmasound_deinit" [sound/oss/dmasound/dmasound_q40.ko] undefined!
> 
> I suspect your patch now breaks the case where multiple drivers are
> built-in, because that puts the same global symbols into vmlinux more
> than once.

True dat.

>> -EXPORT_SYMBOL(dmasound);
>> -EXPORT_SYMBOL(dmasound_init);
>> -#ifdef MODULE
>> -EXPORT_SYMBOL(dmasound_deinit);
>> -#endif
> 
>  From a very brief look, I would think that removing this #ifdef and
> unconditionally defining dmasound_deinit is the correct solution
> here, to solve the case of the core driver being built-in but called
> from a loadable module, the Makefile logic is otherwise correct.

OK, thanks for the info.
I'm not going to spend any more time on it...

-- 
~Randy