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From:   Olof Johansson <olof@lixom.net>
Date:   Fri, 28 Jun 2019 11:44:10 +0800
Message-ID: <CAOesGMjqhEi8rEnYy8JxvRV8HE_eRxfiXtmZNErWYwAX6ni12Q@mail.gmail.com>
Subject: Re: [PATCH] objtool: Be lenient about -Wundef
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Jun 28, 2019 at 8:00 AM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> On Wed, Jun 19, 2019 at 05:03:37AM -0700, Olof Johansson wrote:
> > Some libelf versions use undefined macros, which combined with newer GCC
> > makes for errors from system headers. This isn't overly useful to fail
> > compiling objtool for.
> >
> > Error as seen:
> >
> > cc1: all warnings being treated as errors
> > In file included from arch/x86/../../elf.h:10,
> >                  from arch/x86/decode.c:14:
> > /usr/include/libelf/gelf.h:25:5: error: "__LIBELF_INTERNAL__" is not defined, evaluates to 0 [-Werror=undef]
> >  #if __LIBELF_INTERNAL__
> >      ^~~~~~~~~~~~~~~~~~~
> >
> > For this reason, skip -Wundef on objtool.
> >
> > Signed-off-by: Olof Johansson <olof@lixom.net>
>
> Sorry for the delay, I was out last week and I'm still getting caught
> up.
>
> Which libelf was this?  I'm guessing it's the old non-elfutils version
> which has been unmaintained for 10 years (and which doesn't work with
> objtool anyway).
>
> It would be nice if we could figure out a way to detect that libelf and
> report a more useful error for it.

Yeah, looks like my docker image pulled in the very old libelf 0.8.13,
but has elfutils available. I'll switch it over locally to resolve
this.


-Olof