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

From: Jessica Yu
Date: Wed Apr 01 2020 - 04:00:41 EST


+++ John Stultz [31/03/20 15:09 -0700]:
On Tue, Mar 31, 2020 at 2:58 AM Jessica Yu <jeyu@xxxxxxxxxx> wrote:
+++ John Stultz [30/03/20 23:25 -0700]:
>On Mon, Mar 30, 2020 at 10:49 PM John Stultz <john.stultz@xxxxxxxxxx> 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an outdated Module.symvers file for example, you will see the "FATAL: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