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Re: [PATCH] PR ld/19636: [x86] Resolve undefweak and defined symbols in executable
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Cary Coutant <ccoutant at gmail dot com>
- Cc: Michael Matz <matz at suse dot de>, Binutils <binutils at sourceware dot org>
- Date: Wed, 24 Feb 2016 15:20:06 -0800
- Subject: Re: [PATCH] PR ld/19636: [x86] Resolve undefweak and defined symbols in executable
- Authentication-results: sourceware.org; auth=none
- References: <20160223175814 dot GA2858 at intel dot com> <alpine dot LSU dot 2 dot 20 dot 1602241541430 dot 20277 at wotan dot suse dot de> <CAMe9rOoxU43=dhGYZZGQtWhfbU-sGRoaiiJ7PfPNtzSc05-t-A at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241552020 dot 20277 at wotan dot suse dot de> <CAMe9rOpEWKVVP=-o0t0emkjKR0-xqnn-YZ5C5nfa=0E4BkEZaw at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241709410 dot 20277 at wotan dot suse dot de> <CAMe9rOr5qa_PBJA3oDENWErRfrojtzC1ncXaWwyh-1EAczPn-g at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241749340 dot 20277 at wotan dot suse dot de> <CAMe9rOrSNYV_x-5aU7K+hXHNrinE9Co8y1F5VUkY+SoRQize=g at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241753490 dot 20277 at wotan dot suse dot de> <CAMe9rOpZNHtKRvx+5QurEOcVU96WEQuBRPJ6UorocjE-8Jd+vQ at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241808400 dot 20277 at wotan dot suse dot de> <CAMe9rOpAkC238Gvji0rf1_wBqEAZDDeTkhp_o-BirUrTa622aA at mail dot gmail dot com> <alpine dot LSU dot 2 dot 20 dot 1602241843180 dot 20277 at wotan dot suse dot de> <CAJimCsG=1u_yM6SBFAxCxB4JvWtxO5fZ22+OmG6UC_RYON3DdA at mail dot gmail dot com>
On Wed, Feb 24, 2016 at 3:08 PM, Cary Coutant <ccoutant@gmail.com> wrote:
> FWIW, gold used to leave references to weak undefs for the dynamic
> loader to resolve. We got complaints, and changed it to match gnu ld's
> behavior:
>
> https://sourceware.org/ml/binutils/2008-04/msg00019.html
>
> https://sourceware.org/ml/binutils/2008-04/msg00269.html
>
> I'd prefer not to change ld after having already changed gold to match
> -- especially so when that change was motivated by user complaints.
>
> Daniel replied to the first of the above messages, suggesting that the
> existing ld behavior was surprising, and I agreed. Ian's response was:
>
>> Based on this discussion, I think we should go ahead and commit this
>> to gold. It makes gold act like GNU ld. Clearly more thought is
>> required before changing the linker behaviour in this area.
>
> I suppose this thread can be considered "more thought", but it hasn't
> swayed me. We've had eight more years worth of installed base using
> the current behavior since that discussion.
>
Generate a dynamic relocation against undefined weak symbol
isn't an option for x86-64 if input isn't PIC due to run-time relocation
overflow in .text section.
--
H.J.