From: "H.J. Lu" <hjl.tools@gmail.com>
To: Michael Matz <matz@suse.de>
Cc: 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: <CAMe9rOpQ4Fwk7wJNQuW_5VFuZTApuixt5e=NdrUmZccYK17cCg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.20.1602231756490.20277@wotan.suse.de>
On Tue, Feb 23, 2016 at 9:01 AM, Michael Matz <matz@suse.de> wrote:
> Hi,
>
> On Tue, 23 Feb 2016, H.J. Lu wrote:
>
>> >> Not only we need to change defined weak symbol behavior, we also need
>> >> to change undefined non-weak symbol behavior when taking its address.
>> >
>> > Why? An undefined non-weak symbol reference leads to a linker error,
>> > done. Why change that?
>>
>> Make it "external non-weak symbol", which is a symbol defined in a
>> shared object.
>
> What would you like to change in behaviour for them (and why must it be
> done at the same time as changing something for weak symbols)? A
> reference to the address of such a function symbol from an executable
> resolves to the plt slot currently (which in turn is exported, so that
> address references from other modules resolve to the same). A reference
> to a non-function symbol is loaded from the got. In all cases must this
> symbol be defined somewhere (otherwise linker error), so I don't see what
> we need to change, nor why that would force DT_TEXTREL (or the compiler to
> emit PIC like code).
>
At run-time, there is no difference between weak defined and non-weak
defined symbols. If we change defined weak symbol behavior, we also
need to change defined non-weak symbol behavior.
--
H.J.
next prev parent reply other threads:[~2016-02-23 17:10 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 [this message]
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
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
2016-01-01 0:00 ` H.J. Lu
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