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Re: [PATCH] PR ld/19636: [x86] Resolve undefweak and defined symbols in executable
- From: Michael Matz <matz at suse dot de>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: binutils at sourceware dot org
- Date: Wed, 24 Feb 2016 15:45:00 +0100 (CET)
- 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>
Hi,
On Tue, 23 Feb 2016, H.J. Lu wrote:
> For i386 and x86-64, undefined weak and defined symbols are resolved
> without dynamic relocation when creating executable. Undefined weak
> symbols aren't needed in the dynamic symbol table in executable. One
> exception is on i386, we need undefined weak symbols in the dynamic
> symbol table in PIE if input relocatable files contain branchs without
> PLT so that we can branch to 0 with dynamic relocation in text section.
Um, wait. Have you now changed it so that this program won't work anymore
(no matter if PIC or non-PIC)?:
extern void undef() __attribute__((weak));
int main()
{
if (undef)
undef ();
return 0;
}
> This makes behaviors of static excutable, dynamic excutable and position
> independent executable consistent with references to undefined weak and
> defined symbols, regardless if the relocatable input is compiled with
> PIC or not.
Because, while consistence is good, it's more important that the above
program keeps working (and if only under PIC).
Ciao,
Michael.