Re: prelink ok?

["tong changda" <tongcd at hotmail dot com>]

Hello
   I had applied the prelink on my Intel Xscale PDA, It quicken things 
much faster, It is a wonderful tool.
   But I still thought prelink should be give UND symbol the address on 
embedded device. Only for PC, we should care  shared library or binary is 
usable when prelinking can't be used.
   I found the sequence of resolving UND symbol according the ldd result, 
So I want to place the most-likely library to be the first lib that relied, 
Is there a tool to change the sequence of library relies without recompile 
the source code?

> From: Jakub Jelinek <jakub@redhat.com>
> Reply-To: Jakub Jelinek <jakub@redhat.com>
> To: tong changda <tongcd@hotmail.com>
> CC: libc-alpha@sources.redhat.com
> Subject: Re: prelink ok?
> Date: Wed, 15 Jun 2005 07:54:32 +0200
>
> On Wed, Jun 15, 2005 at 11:27:10AM +0800, tong changda wrote:
> > Hello everybody
> > sorry if not proper to ask here
> >
> > I use prelink on arm dynamic library and execute file. prelink -av 
finished
> > without warning, but readelf shows some unexpects:
> >
> > /lib/libavformat.so.1               420b8000-420fb8b8
> > 0x00000001 (NEEDED)                 Shared library: [libc.so.6]
> > .....
> > 57: 420faacc    32 OBJECT  GLOBAL DEFAULT   13 pam_image_format
> > 58: 00000000   252 FUNC    GLOBAL DEFAULT  UND strchr@GLIBC_2.0 (2)
> >
> > our symbol external is left unsolved, but local symbol are solved the
> > address normally,
> > I think after prelink there should be no UND symbol,Did I compile the
> > library the wrong way?
>
> prelink doesn't change undefined symbols in this way.
> All it does is 1) relocate the shared library to a certain fixed address
> 2) apply relocations 3) prepare things for the dynamic linker, so that if
> all libraries and the binary are mapped in the right places and have not
> been changed since prelinking, ld.so can skip all the relocation handling
> and instead just apply some fixups
> The shared libraries must still be usable even when prelinking can't be
> used.  So e.g. the changing of undefined symbols you are expecting
> (why?) certainly must not be done, as otherwise the shared library
> or binary wouldn't be usable when prelinking can't be used.
> Please read prelink's documentation if you want to know more.
>
> 	Jakub

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