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Date:   Thu, 5 Sep 2019 13:16:17 +0200
From:   Jessica Yu <jeyu@kernel.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Matthew Dharm <mdharm-usb@one-eyed-alien.net>,
        Guenter Roeck <linux@roeck-us.net>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Lucas De Marchi <lucas.de.marchi@gmail.com>,
        Martijn Coenen <maco@android.com>,
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Subject: Re: [usb-storage] Re: [PATCH v4 12/12] RFC: watchdog: export core
 symbols in WATCHDOG_CORE namespace
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+++ Arnd Bergmann [05/09/19 12:52 +0200]:
>On Thu, Sep 5, 2019 at 12:41 PM Jessica Yu <jeyu@kernel.org> wrote:
>> +++ Matthew Dharm [04/09/19 09:16 -0700]:
>> >On Wed, Sep 4, 2019 at 5:12 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
>> >HOWEVER, I have one question:  If these patches are included, and
>> >someone wants to introduce a bit of code which needs to use two
>> >symbols from different namespaces but with the same name, can that be
>> >done?  That is, if driver A has symbol 'foo' and driver B has symbol
>> >'foo' (both in their respective namespaces), and driver C wants to use
>> >A.foo and B.foo, can that be supported?
>>
>> As of now, we currently don't support this - modpost will warn if a
>> symbol is exported more than once (across modules + vmlinux), and the
>> module loader currently assumes exported symbol names are unique.  Do
>> you have a concrete use case? If there is a strong need for this, I
>> don't think it'd be too hard to implement.
>
>I think what would prevent this from working in general is that having
>two modules with the same exported symbol in different namespaces
>won't link if you try to build both modules into the kernel itself.
>
>      Arnd

Ah yeah, you are right. I only tried building an identically named
exported symbol in a module and in the kernel, and there I got away
with a modpost warning. But this breaks when building the module into
the kernel, so I guess this is out of the question.

Thanks,

Jessica