Subject: Re: 'prebind' implementation (was Re: HEADS UP: migration to fully dynamic linked "base" system)
To: Jason R Thorpe <>
From: Bang Jun-Young <>
List: tech-userlevel
Date: 08/29/2002 00:15:36
On Wed, Aug 28, 2002 at 07:36:14AM -0700, Jason R Thorpe wrote:
> On Wed, Aug 28, 2002 at 09:28:26PM +0900, Bang Jun-Young wrote:
>  > More thoughts on prebinding:
>  >  
>  >  - '.pgot' would be better than '.pplt'. First, '.got' is mapped 
>  >    read-writable but '.plt' read-only, and second, it's much easier to
>  >    deal with GOT entries than PLT entries. '.plt' is code section so
>  >    you should know how jmp instruction is encoded for each archtecture. 
> Err, either way, you should be able to lift the code for the relocations,
> for both PLT and GOT objects, from ld.elf_so ... in fact, I'd think that
> you'd want to share as much code as possible...
> Sure, PLT entires are generally lazy-bound, but it would still be a
> performance benefit to pre-bind them, yes?

Yes. Especially, prebinding would be of more benefit to small binaries
like those in /bin and /sbin.

>  >  - Save base addresses of shared objects in some place of the binary,
>  >    and if they are different than actual base addresses of shared objects
>  >    mapped in memory, dynamic linker performs additional fixup process by
>  >    adding/subtracting delta to/from each entry in '.pgot'. This would
>  >    be simple and not be a time-taking job. 
> Hm, yah, that sounds like a good idea.

Thanks. ;-)


Bang Jun-Young <>