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From: Florian Weimer <fweimer@redhat.com>
To: Michael Matz <matz@suse.de>
Cc: x86-64-abi@googlegroups.com,  Binutils <binutils@sourceware.org>,  "H.J. Lu" <hjl.tools@gmail.com>,  GNU C Library <libc-alpha@sourceware.org>,  Mark Wielaard <mark@klomp.org>,  Cary Coutant <ccoutant@gmail.com>,  Nick Clifton <nickc@redhat.com>,  Carlos O'Donell <carlos@redhat.com>,  Szabolcs Nagy <szabolcs.nagy@arm.com>
Subject: Re: PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold
References: <CAMe9rOrrayKnc_cPm4SmnDnUGLbBUmOYMBTMOM8KLAHVmb=rUQ@mail.gmail.com>
	<13a92cb0-a993-f684-9a96-e02e4afb1bef@redhat.com>
	<87sh2547ib.fsf@oldenburg.str.redhat.com>
	<alpine.LSU.2.21.1809211232400.7867@wotan.suse.de>
Date: Fri, 21 Sep 2018 13:04:00 -0000
In-Reply-To: <alpine.LSU.2.21.1809211232400.7867@wotan.suse.de> (Michael
	Matz's message of "Fri, 21 Sep 2018 12:55:16 +0000 (UTC)")
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* Michael Matz:

> (didn't take part in the side meeting, so sorry if this was discussed)

I don't think this came up.

> On Wed, 19 Sep 2018, Florian Weimer wrote:
>
>> Distributions have built binaries with 8-byte-aligned GNU property 
>> notes.
>
> Which ones?

Fedora 29 and downstream.

> Thing is, there are also binaries (or there could be) that are currently 
> "valid" that the align-8 approach makes invalid, so why say that's a 
> problem for the align-4 approach, but not for the align-8 one?

The 4-byte-aligned GNU property notes are ignored by glibc even if they
are otherwise syntactically valid.  So even if there is a hypothetical
distribution that is mostly built with binutils gold and thus has
4-byte-aligned GNU property notes, it would still not work as intended,
which makes me believe that such a distribution does not exist. 8-)

Thanks,
Florian