From: "H.J. Lu" <hjl.tools@gmail.com>
To: Michael Matz <matz@suse.de>
Cc: "Carlos O'Donell" <carlos@redhat.com>,
Alan Modra <amodra@gmail.com>,
gnu-gabi@sourceware.org
Subject: Re: Specify how undefined weak symbol should be resolved in executable
Date: Fri, 01 Jan 2016 00:00:00 -0000 [thread overview]
Message-ID: <CAMe9rOrBif7TL2QhGC4mmQhdZ-YM48V6r-71VX5k4JOmNgurGg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.20.1602241801070.20277@wotan.suse.de>
On Wed, Feb 24, 2016 at 9:08 AM, Michael Matz <matz@suse.de> wrote:
> Hi,
>
> On Wed, 24 Feb 2016, H.J. Lu wrote:
>
>> >> I was saying as far as ld was concerned, weak defined and non-weak
>> >> defined dynamic symbols would be treated equally at run-time. Do you
>> >> agree with me?
>> >
>> > I at least don't. The difference is that a defined weak symbol (at
>> > link edit time) might become undefined at runtime. A defined non-weak
>> > symbol can't. So they have to be handled differently.
>> >
>>
>> How?
>
> Like right now (mostly)? Resolution of weak symbols needs to be deferred
> to the dynamic linker, in particular they mustn't be resolved (to either
> zero or an address) at link edit time. There's one case where weak
> symbols can be resolved early: if at link edit time the executable itself
> provides a definition of 'foo' then weak references can be directly
> resolved to that one (because at runtime of that exectuable there's no
> possibility to not have this symbol defined).
>
> To not do that (i.e. resolve them always at link edit time) breaks various
> current uses of weak symbols. We could do that of course, but I don't
> think that would be useful to users.
I suggest you raise this issue at
https://groups.google.com/forum/#!forum/generic-abi
--
H.J.
next prev parent reply other threads:[~2016-02-24 17:23 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-01 0:00 H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Alan Modra
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` Szabolcs Nagy
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Alan Modra
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Alan Modra
2016-01-01 0:00 ` Carlos O'Donell
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu [this message]
2016-01-01 0:00 ` Michael Matz
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
2016-01-01 0:00 ` H.J. Lu
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