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Re: ELF extension for starting symbol search from module dependencies
- From: Jakub Jelinek <jakub at redhat dot com>
- To: "Maciej W. Rozycki" <macro at ds2 dot pg dot gda dot pl>
- Cc: Luca Barbieri <ldb at ldb dot ods dot org>, Debian-Devel ML <debian-devel at lists dot debian dot org>, GNU binutils ML <binutils at sources dot redhat dot com>, GNU libc ML <libc-alpha at sources dot redhat dot com>
- Date: Thu, 22 Aug 2002 11:23:00 +0200
- Subject: Re: ELF extension for starting symbol search from module dependencies
- References: <1029939164.1828.25.camel@ldb> <Pine.GSO.3.96.1020822102531.22495A-100000@delta.ds2.pg.gda.pl>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Thu, Aug 22, 2002 at 10:35:33AM +0200, Maciej W. Rozycki wrote:
> On 21 Aug 2002, Luca Barbieri wrote:
>
> > This is a proposal (including patches) for a GNU extension to the ELF
> > executable format that adds a flag that causes the dynamic loader to
> > start searching for symbols referenced by modules with the flag set from
> > the module itself and its immediate dependencies. If the symbol is not
> > found in this way, the dynamic linker continues the search as usual.
> >
> > This extension would be useful to allow to load in the same address
> > space multiple libraries that define identical symbols, that would be
> > used by different modules possibly unaware of each other's use of such
> > symbols.
>
> Hmm, what if two functions which get imported from different versions of
> the same library operate on a static (private to the library) variable
> that is needed for a proper operation for some reason? You'd better
> rebuild the sources to use a single version of each library instead.
Or, even better, introduce symbol versioning for libpng.so and maintain it
ABI compatible from this point on...
Jakub