linux-kernel - Re: [PATCH v4 00/10] klp-convert livepatch build tooling

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Message-ID: <76da6ab0-5540-d9ff-c5ea-6dc31a39c744@redhat.com>
Date:   Tue, 25 Jun 2019 09:24:20 -0400
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Miroslav Benes <mbenes@...e.cz>, Petr Mladek <pmladek@...e.com>
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v4 00/10] klp-convert livepatch build tooling

On 6/25/19 7:36 AM, Miroslav Benes wrote:
> 
 > [ ... snip ... ]
 >
> So I made a couple of experiments and found that GCC is somehow involved.
> If klp-convert (from scripts/livepatch/) is compiled with our GCC 4.8.5
> from SLE12, the output is incorrect. If I compile it with GCC 7.4.0 from
> openSUSE Leap 15.1, the output is correct.
> 
> If I revert commit d59cadc0a8f8 ("[squash] klp-convert: make
> convert_rela() list-safe") (from Joe's expanded github tree), the problem
> disappears.
> 
> I haven't spotted any problem in the code and I cannot explain a
> dependency on GCC version. Any ideas?
> 

Thanks for revisiting and debugging this.  Narrowing it down to my "fix" 
to convert_rela() should be helpful.

In my case, I was probably testing with RHEL-8, which has gcc 8.2 vs 
RHEL-7 which has gcc 4.8.  I'll have to make sure to try with a few 
different versions for the next round.

-- Joe