gold/README

   1 gold is an ELF linker.  It is intended to have complete support for
   2 ELF and to run as fast as possible on modern systems.  For normal use
   3 it is a drop-in replacement for the older GNU linker.
   4
   5 gold is part of the GNU binutils.  See ../binutils/README for more
   6 general notes, including where to send bug reports.
   7
   8 gold was originally developed at Google, and was contributed to the
   9 Free Software Foundation in March 2008.  At Google it was designed by
  10 Ian Lance Taylor, with major contributions by Cary Coutant, Craig
  11 Silverstein, and Andrew Chatham.
  12
  13 The existing GNU linker manual is intended to be accurate
  14 documentation for features which gold supports.  gold supports most of
  15 the features of the GNU linker for ELF targets.  Notable
  16 omissions--features of the GNU linker not currently supported in
  17 gold--are:
  18   * MRI compatible linker scripts
  19   * cross-reference reports (--cref)
  20   * various other minor options
  21
  22
  23 Notes on the code
  24 =================
  25
  26 These are some notes which may be helpful to people working on the
  27 source code of gold itself.
  28
  29 gold is written in C++.  It is a GNU program, and therefore follows
  30 the GNU formatting standards as modified for C++.  Source documents in
  31 order of decreasing precedence:
  32     http://www.gnu.org/prep/standards/
  33     http://gcc.gnu.org/onlinedocs/libstdc++/manual/source_code_style.html
  34     http://www.zembu.com/eng/procs/c++style.html
  35
  36 The linker is intended to have complete support for cross-compilation,
  37 while still supporting the normal case of native linking as fast as
  38 possible.  In order to do this, many classes are actually templates
  39 whose parameter is the ELF file class (e.g., 32 bits or 64 bits).  The
  40 C++ code is the same, but we don't pay the execution time cost of
  41 always using 64-bit integers if the target is 32 bits.  Many of these
  42 class templates also have an endianness parameter: true for
  43 big-endian, false for little-endian.
  44
  45 The linker is multi-threaded.  The Task class represents a single unit
  46 of work.  Task objects are stored on a single Workqueue object.  Tasks
  47 communicate via Task_token objects.  Task_token objects are only
  48 manipulated while holding the master Workqueue lock.  Relatively few
  49 mutexes are used.
  50
  51
  52 Build requirements
  53 ==================
  54
  55 The gold source code uses templates heavily.  Building it requires a
  56 recent version of g++.  g++ 4.0.3 and 4.1.3 are known to work.  g++
  57 3.2, 3.4.3, and 4.1.2 are known to fail.
  58
  59 The linker script parser uses features which are only in newer
  60 versions of bison.  bison 2.3 is known to work.  bison 1.26 is known
  61 to fail.  If you are building gold from an official binutils release,
  62 the bison output should already be included.
  63
  64 \f
  65 Copyright (C) 2012-2020 Free Software Foundation, Inc.
  66
  67 Copying and distribution of this file, with or without modification,
  68 are permitted in any medium without royalty provided the copyright
  69 notice and this notice are preserved.