PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold

[Florian Weimer]

* 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