What is prelink?

Prelink is a program, totally not the same thing with Linux's ld.so's LD_PRELOAD environment variable.

       prelink is a program which modifies ELF shared libraries and ELF dynam-
       ically linked binaries, so that the time which dynamic linker needs for
       their relocation at startup significantly decreases  and  also  due  to
       fewer  relocations the run-time memory consumption decreases too (espe-
       cially number of unshareable pages).  Such  prelinking  information  is
       only  used  if  all its dependant libraries have not changed since pre-
       linking, otherwise programs are relocated normally.

       prelink first collects ELF binaries which should be prelinked  and  all
       the  ELF shared libraries they depend on. Then it assigns a unique vir-
       tual address space slot for each library and relinks the shared library
       to  that base address.  When the dynamic linker attempts to load such a
       library, unless that virtual address space slot is already occupied, it
       will  map it into the given slot.  After this is done, prelink with the
       help of dynamic linker  resolves  all  relocations  in  the  binary  or
       library against its dependant libraries and stores the relocations into
       the ELF object.  It also stores  a  list  of  all  dependant  libraries
       together  with  their  checksums into the binary or library.  For bina-
       ries, it also computes a list of conflicts (relocations  which  resolve
       differently  in  the  binary’s  symbol search scope than in the smaller
       search scope in which the dependant library was resolved) and stores it
       into a special ELF section.

 

For informations about LD_PRELOAD, refer to linker, load, library book P243.