Linker and Libraries Guide

Symbol Elimination

An extension to symbol reduction is the elimination of a symbol entry from an object's symbol table. Local symbols are only maintained in an object's .symtab symbol table. This entire table can be removed from the object by using the link-editor's -s option, or strip(1). On occasion, you might want to maintain the .symtab symbol table but remove selected local symbol definitions.

Symbol elimination can be carried out using the mapfile keyword ELIMINATE. As with the local directive, symbols can be individually defined, or the symbol name can be defined as the special auto-elimination directive “*”. The following example shows the elimination of the symbol bar for the previous symbol reduction example.

$ cat mapfile
$mapfile_version 2
$ cc -o -M mapfile -G foo.c bar.c
$ elfdump -sN.symtab | egrep 'foo$|bar$|str$'
      [26]  0x00010690 0x00000004  OBJT LOCL  H    0 .data          str
      [44]  0x000004e8 0x0000002c  FUNC GLOB  D    0 .text          foo

The -B eliminate option can be used to assert the auto-elimination directive “*” from the command line.