70 lines
2.8 KiB
Plaintext
70 lines
2.8 KiB
Plaintext
gold is an ELF linker. It is intended to have complete support for
|
||
ELF and to run as fast as possible on modern systems. For normal use
|
||
it is a drop-in replacement for the older GNU linker.
|
||
|
||
gold is part of the GNU binutils. See ../binutils/README for more
|
||
general notes, including where to send bug reports.
|
||
|
||
gold was originally developed at Google, and was contributed to the
|
||
Free Software Foundation in March 2008. At Google it was designed by
|
||
Ian Lance Taylor, with major contributions by Cary Coutant, Craig
|
||
Silverstein, and Andrew Chatham.
|
||
|
||
The existing GNU linker manual is intended to be accurate
|
||
documentation for features which gold supports. gold supports most of
|
||
the features of the GNU linker for ELF targets. Notable
|
||
omissions--features of the GNU linker not currently supported in
|
||
gold--are:
|
||
* MRI compatible linker scripts
|
||
* cross-reference reports (--cref)
|
||
* various other minor options
|
||
|
||
|
||
Notes on the code
|
||
=================
|
||
|
||
These are some notes which may be helpful to people working on the
|
||
source code of gold itself.
|
||
|
||
gold is written in C++. It is a GNU program, and therefore follows
|
||
the GNU formatting standards as modified for C++. Source documents in
|
||
order of decreasing precedence:
|
||
http://www.gnu.org/prep/standards/
|
||
http://gcc.gnu.org/onlinedocs/libstdc++/manual/source_code_style.html
|
||
http://www.zembu.com/eng/procs/c++style.html
|
||
|
||
The linker is intended to have complete support for cross-compilation,
|
||
while still supporting the normal case of native linking as fast as
|
||
possible. In order to do this, many classes are actually templates
|
||
whose parameter is the ELF file class (e.g., 32 bits or 64 bits). The
|
||
C++ code is the same, but we don't pay the execution time cost of
|
||
always using 64-bit integers if the target is 32 bits. Many of these
|
||
class templates also have an endianness parameter: true for
|
||
big-endian, false for little-endian.
|
||
|
||
The linker is multi-threaded. The Task class represents a single unit
|
||
of work. Task objects are stored on a single Workqueue object. Tasks
|
||
communicate via Task_token objects. Task_token objects are only
|
||
manipulated while holding the master Workqueue lock. Relatively few
|
||
mutexes are used.
|
||
|
||
|
||
Build requirements
|
||
==================
|
||
|
||
The gold source code uses templates heavily. Building it requires a
|
||
recent version of g++. g++ 4.0.3 and 4.1.3 are known to work. g++
|
||
3.2, 3.4.3, and 4.1.2 are known to fail.
|
||
|
||
The linker script parser uses features which are only in newer
|
||
versions of bison. bison 2.3 is known to work. bison 1.26 is known
|
||
to fail. If you are building gold from an official binutils release,
|
||
the bison output should already be included.
|
||
|
||
|
||
Copyright (C) 2012 Free Software Foundation, Inc.
|
||
|
||
Copying and distribution of this file, with or without modification,
|
||
are permitted in any medium without royalty provided the copyright
|
||
notice and this notice are preserved.
|