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From:   Thomas Garnier <thgarnie@google.com>
Date:   Fri, 1 Feb 2019 09:35:00 -0800
Message-ID: <CAJcbSZEkc2Rc7uemA0Qw2uJhvNciLRxPrMVSQV_-O_N8zozZ_Q@mail.gmail.com>
Subject: Re: [PATCH v6 15/27] compiler: Option to default to hidden symbols
To:     Adrian Hunter <adrian.hunter@intel.com>
Cc:     Thomas Garnier <thgarnie@chromium.org>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        kristen@linux.intel.com, Thomas Gleixner <tglx@linutronix.de>,
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On Fri, Feb 1, 2019 at 12:24 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> On 31/01/19 9:24 PM, Thomas Garnier wrote:
> > Provide an option to default visibility to hidden except for key
> > symbols. This option is disabled by default and will be used by x86_64
> > PIE support to remove errors between compilation units.
> >
> > The default visibility is also enabled for external symbols that are
> > compared as they maybe equals (start/end of sections). In this case,
> > older versions of GCC will remove the comparison if the symbols are
> > hidden. This issue exists at least on gcc 4.9 and before.
>
> What does this mean, if anything, for what/how symbols appear in /proc/kallsyms?

No, they will still appear in kallsyms. Some symbols are not absolute
anymore or moved sections but still present.

-- 
Thomas