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 66 Copyright (C) 2012-2014 Free Software Foundation, Inc. 67 68 Copying and distribution of this file, with or without modification, 69 are permitted in any medium without royalty provided the copyright 70 notice and this notice are preserved. 71
