linux-kernel - Re: [PATCH v2] modpost: move the namespace field in Module.symvers last

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Message-ID: <20200401080033.GA12505@linux-8ccs>
Date:   Wed, 1 Apr 2020 10:00:34 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     John Stultz <john.stultz@...aro.org>
Cc:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Matthias Maennich <maennich@...gle.com>,
        Lucas De Marchi <lucas.de.marchi@...il.com>,
        stable <stable@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] modpost: move the namespace field in Module.symvers
 last

+++ John Stultz [31/03/20 15:09 -0700]:
>On Tue, Mar 31, 2020 at 2:58 AM Jessica Yu <jeyu@...nel.org> wrote:
>> +++ John Stultz [30/03/20 23:25 -0700]:
>> >On Mon, Mar 30, 2020 at 10:49 PM John Stultz <john.stultz@...aro.org> wrote:
>> >> The only difference I can find is that the Module.symvers in the
>> >> external module project doesn't seem to have a tab at the end of each
>> >> line (where as Module.symvers for the kernel - which doesn't seem to
>> >> have any namespace names - does).
>> >>
>> >> Is there something I need to tweak on the external Kbuild to get
>> >> Module.symvers to be generated properly (with the empty tab at the
>> >> end) for this new change?
>> >> Or does the parser need to be a bit more flexible?
>> >>
>> >
>> >One extra clue on this: I noticed the external module Makefile had
>> >KBUILD_EXTRA_SYMBOLS="$(EXTRA_SYMBOLS)"  in the $(MAKE) string, where
>> >EXTRA_SYMBOLS pointed to some files that no longer exist.  I removed
>> >the KBUILD_EXTRA_SYMBOLS= argument, and magically, the generated
>> >Module.symvers now had tabs at the end of each line.
>> >
>> >I wonder if there some path in the KBUILD_EXTRA_SYMBOLS= handling that
>> >isn't generating the output in the same way?
>>
>> I'm afraid we're going to need some specifics on reproducing this
>> issue. Could you provide a reproducer or steps on how to reproduce? I
>> have not been able to trigger this problem even with
>> KBUILD_EXTRA_SYMBOLS pointing to an invalid path (I also tested with
>> valid paths).
>>
>> I tested with a skeleton external module that exports two functions,
>> one with a namespace and one without. I built this module against the
>> latest v5.6 kernel. The generated Module.symvers was correct - the
>> namespaced function had the namespace at the end and the other
>> function without a namespace had a tab at the end.
>>
>> I also tested with two external modules, one with a symbol dependency
>> on the other, so KBUILD_EXTRA_SYMBOLS usage is required here. The
>> generated Module.symvers was also correct here.
>>
>> The only advice I can offer at this time is that all external modules
>> must be built against the new kernel to generate a correctly formated
>> Module.symvers file. If you have any KBUILD_EXTRA_SYMBOLS pointing to
>> an outdated Module.symvers file for example, you will see the "FATAL:
>> parse error in symbol dump file" error.
>
>Well, my apologies.  :(  In the light of day, this isn't reproducing
>anymore. I'm a bit at a loss as to why I was tripping over it so
>regularly before, but I suspect something in the build is leaving a
>stale Modules.symvers around from before this patch landed.
>
>Terribly sorry for the noise.

No problem, thank for reporting back!

Jessica