Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
LD(1)			     GNU Development Tools			 LD(1)

NAME
       ld - Using LD, the GNU linker

SYNOPSIS
       ld [options] objfile ...

DESCRIPTION
       ld  combines a number of	object and archive files, relocates their data
       and ties	up symbol references. Usually the last	step  in  compiling  a
       program is to run ld.

       ld  accepts  Linker  Command  Language  files  written in a superset of
       AT&T's Link Editor Command Language syntax,  to	provide	 explicit  and
       total control over the linking process.

       This  man page does not describe	the command language; see the ld entry
       in "info", or the manual	ld: the	GNU linker, for	full  details  on  the
       command language	and on other aspects of	the GNU	linker.

       This version of ld uses the general purpose BFD libraries to operate on
       object files. This allows ld to read, combine, and write	 object	 files
       in  many	 different  formats---for example, COFF	or "a.out".  Different
       formats may be linked together to produce any available kind of	object
       file.

       Aside  from  its	flexibility, the GNU linker is more helpful than other
       linkers in providing diagnostic information.  Many linkers abandon exe-
       cution  immediately  upon  encountering an error; whenever possible, ld
       continues executing, allowing you to identify other errors (or, in some
       cases, to get an	output file in spite of	the error).

       The GNU linker ld is meant to cover a broad range of situations,	and to
       be as compatible	as possible with other linkers.	 As a result, you have
       many choices to control its behavior.

OPTIONS
       The  linker  supports a plethora	of command-line	options, but in	actual
       practice	few of them are	used in	any particular context.	 For instance,
       a  frequent  use	of ld is to link standard Unix object files on a stan-
       dard, supported Unix  system.   On  such	 a  system,  to	 link  a  file
       "hello.o":

	       ld -o <output> /lib/crt0.o hello.o -lc

       This  tells ld to produce a file	called output as the result of linking
       the file	"/lib/crt0.o" with "hello.o" and the library  "libc.a",	 which
       will come from the standard search directories.	(See the discussion of
       the -l option below.)

       Some of the command-line	options	to ld may be specified at any point in
       the command line.  However, options which refer to files, such as -l or
       -T, cause the file to be	read at	the point at which the option  appears
       in  the	command	 line,	relative  to  the  object files	and other file
       options.	 Repeating non-file options with  a  different	argument  will
       either  have  no	 further  effect, or override prior occurrences	(those
       further to the left on the command line)	of that	option.	 Options which
       may  be meaningfully specified more than	once are noted in the descrip-
       tions below.

       Non-option arguments are	object files  or  archives  which  are	to  be
       linked  together.   They	 may follow, precede, or be mixed in with com-
       mand-line options, except that an  object  file	argument  may  not  be
       placed between an option	and its	argument.

       Usually	the  linker  is	invoked	with at	least one object file, but you
       can specify other forms of binary input files using  -l,	 -R,  and  the
       script  command	language.   If no binary input files at	all are	speci-
       fied, the linker	does not produce any output, and issues	the message No
       input files.

       If  the	linker can not recognize the format of an object file, it will
       assume that it is a linker script.  A script specified in this way aug-
       ments  the  main	 linker	 script	 used for the link (either the default
       linker script or	the one	specified by using -T).	 This feature  permits
       the  linker  to link against a file which appears to be an object or an
       archive,	but actually  merely  defines  some  symbol  values,  or  uses
       "INPUT"	or  "GROUP"  to	 load  other  objects.	Note that specifying a
       script in this way merely augments the main linker script; use  the  -T
       option to replace the default linker script entirely.

       For  options  whose  names  are	a single letter, option	arguments must
       either follow the option	letter without intervening whitespace,	or  be
       given  as  separate  arguments  immediately  following  the option that
       requires	them.

       For options whose names are multiple letters, either one	 dash  or  two
       can   precede   the   option   name;  for  example,  -trace-symbol  and
       --trace-symbol are equivalent.  Note - there is one exception  to  this
       rule.   Multiple	 letter	 options  that start with a lower case 'o' can
       only be preceeded by two	dashes.	 This is to reduce confusion with  the
       -o  option.   So	for example -omagic sets the output file name to magic
       whereas --omagic	sets the NMAGIC	flag on	the output.

       Arguments to multiple-letter options must either	be separated from  the
       option  name by an equals sign, or be given as separate arguments imme-
       diately	following  the	option	that  requires	them.	For   example,
       --trace-symbol  foo  and	 --trace-symbol=foo  are  equivalent.	Unique
       abbreviations of	the names of multiple-letter options are accepted.

       Note - if the linker is being invoked indirectly, via a compiler	driver
       (eg gcc)	then all the linker command line options should	be prefixed by
       -Wl, (or	whatever is appropriate	for the	 particular  compiler  driver)
       like this:

		 gcc -Wl,--startgroup foo.o bar.o -Wl,--endgroup

       This  is	 important,  because otherwise the compiler driver program may
       silently	drop the linker	options, resulting in a	bad link.

       Here is a table of the generic command line switches  accepted  by  the
       GNU linker:

       -akeyword
	   This	 option	 is  supported	for  HP/UX compatibility.  The keyword
	   argument must be one	of the strings archive,	 shared,  or  default.
	   -aarchive is	functionally equivalent	to -Bstatic, and the other two
	   keywords are	functionally equivalent	to -Bdynamic.  This option may
	   be used any number of times.

       -Aarchitecture
       --architecture=architecture
	   In  the  current  release of	ld, this option	is useful only for the
	   Intel 960 family of architectures.  In that ld  configuration,  the
	   architecture	argument identifies the	particular architecture	in the
	   960 family, enabling	some safeguards	 and  modifying	 the  archive-
	   library search path.

	   Future  releases  of	ld may support similar functionality for other
	   architecture	families.

       -b input-format
       --format=input-format
	   ld may be configured	to support more	than one kind of object	 file.
	   If  your  ld	 is  configured	this way, you can use the -b option to
	   specify the binary format for input object files that  follow  this
	   option  on the command line.	 Even when ld is configured to support
	   alternative object formats, you don't usually need to specify this,
	   as  ld should be configured to expect as a default input format the
	   most	usual format on	each machine.  input-format is a text  string,
	   the	name  of  a  particular	format supported by the	BFD libraries.
	   (You	can list the available binary formats with objdump -i.)

	   You may want	to use this option if you are linking  files  with  an
	   unusual  binary  format.   You  can	also  use -b to	switch formats
	   explicitly (when linking object files  of  different	 formats),  by
	   including  -b  input-format	before each group of object files in a
	   particular format.

	   The default format is taken from the	environment variable  "GNUTAR-
	   GET".

	   You	can also define	the input format from a	script,	using the com-
	   mand	"TARGET";

       -c MRI-commandfile
       --mri-script=MRI-commandfile
	   For compatibility with linkers produced by MRI, ld  accepts	script
	   files   written  in	an  alternate,	restricted  command  language,
	   described in	the MRI	Compatible Script Files	section	of GNU ld doc-
	   umentation.	Introduce MRI script files with	the option -c; use the
	   -T option to	run linker scripts written in the  general-purpose  ld
	   scripting language.	If MRI-cmdfile does not	exist, ld looks	for it
	   in the directories specified	by any -L options.

       -d
       -dc
       -dp These three options are equivalent; multiple	 forms	are  supported
	   for	compatibility with other linkers.  They	assign space to	common
	   symbols even	if a relocatable output	file is	specified  (with  -r).
	   The script command "FORCE_COMMON_ALLOCATION"	has the	same effect.

       -e entry
       --entry=entry
	   Use	entry  as  the explicit	symbol for beginning execution of your
	   program, rather than	the default entry point.  If there is no  sym-
	   bol	named  entry,  the linker will try to parse entry as a number,
	   and use that	as the entry address (the number will  be  interpreted
	   in  base  10;  you may use a	leading	0x for base 16,	or a leading 0
	   for base 8).

       -E
       --export-dynamic
	   When	creating a dynamically linked executable, add all  symbols  to
	   the	dynamic	 symbol	table.	The dynamic symbol table is the	set of
	   symbols which are visible from dynamic objects at run time.

	   If you do not use this option, the dynamic symbol table  will  nor-
	   mally  contain  only	 those	symbols	 which	are referenced by some
	   dynamic object mentioned in the link.

	   If you use "dlopen" to load a dynamic object	which needs  to	 refer
	   back	 to the	symbols	defined	by the program,	rather than some other
	   dynamic object, then	you will probably need to use this option when
	   linking the program itself.

	   You	can also use the version script	to control what	symbols	should
	   be added to the dynamic symbol table	if the output format  supports
	   it.	See the	description of --version-script	in @ref{VERSION}.

       -EB Link	big-endian objects.  This affects the default output format.

       -EL Link	 little-endian	objects.  This affects the default output for-
	   mat.

       -f
       --auxiliary name
	   When	creating an ELF	shared object, set the	internal  DT_AUXILIARY
	   field  to  the  specified name.  This tells the dynamic linker that
	   the symbol table of the shared object should	be used	as  an	auxil-
	   iary	filter on the symbol table of the shared object	name.

	   If  you later link a	program	against	this filter object, then, when
	   you run the program,	the dynamic linker will	see  the  DT_AUXILIARY
	   field.   If the dynamic linker resolves any symbols from the	filter
	   object, it will first check whether there is	a  definition  in  the
	   shared  object  name.   If there is one, it will be used instead of
	   the definition in the filter	object.	 The shared object  name  need
	   not	exist.	 Thus the shared object	name may be used to provide an
	   alternative implementation of certain functions, perhaps for	debug-
	   ging	or for machine specific	performance.

	   This	 option	 may  be  specified  more than once.  The DT_AUXILIARY
	   entries will	be created in the order	in which they  appear  on  the
	   command line.

       -F name
       --filter	name
	   When	 creating  an  ELF  shared  object, set	the internal DT_FILTER
	   field to the	specified name.	 This tells the	 dynamic  linker  that
	   the symbol table of the shared object which is being	created	should
	   be used as a	filter on the symbol table of the shared object	 name.

	   If  you later link a	program	against	this filter object, then, when
	   you run the program,	the dynamic  linker  will  see	the  DT_FILTER
	   field.   The	 dynamic  linker will resolve symbols according	to the
	   symbol table	of the filter object as	usual, but  it	will  actually
	   link	 to the	definitions found in the shared	object name.  Thus the
	   filter object can be	used to	select a subset	of  the	 symbols  pro-
	   vided by the	object name.

	   Some	 older	linkers	 used  the  -F option throughout a compilation
	   toolchain for specifying object-file	format for both	input and out-
	   put	object	files.	 The GNU linker	uses other mechanisms for this
	   purpose: the	-b, --format, --oformat	options, the "TARGET"  command
	   in  linker  scripts,	and the	"GNUTARGET" environment	variable.  The
	   GNU linker will ignore the -F  option  when	not  creating  an  ELF
	   shared object.

       -fini name
	   When	 creating  an  ELF executable or shared	object,	call NAME when
	   the executable or shared object is unloaded,	by setting DT_FINI  to
	   the	address	 of the	function.  By default, the linker uses "_fini"
	   as the function to call.

       -g  Ignored.  Provided for compatibility	with other tools.

       -Gvalue
       --gpsize=value
	   Set the maximum size	of objects to be optimized using the GP	regis-
	   ter	to size.  This is only meaningful for object file formats such
	   as MIPS ECOFF which supports	putting	large and small	 objects  into
	   different sections.	This is	ignored	for other object file formats.

       -hname
       -soname=name
	   When	creating an ELF	shared	object,	 set  the  internal  DT_SONAME
	   field  to  the specified name.  When	an executable is linked	with a
	   shared object which has a DT_SONAME field, then when	the executable
	   is  run  the	 dynamic linker	will attempt to	load the shared	object
	   specified by	the DT_SONAME field rather than	 the  using  the  file
	   name	given to the linker.

       -i  Perform an incremental link (same as	option -r).

       -init name
	   When	 creating  an  ELF executable or shared	object,	call NAME when
	   the executable or shared object is loaded, by  setting  DT_INIT  to
	   the	address	 of the	function.  By default, the linker uses "_init"
	   as the function to call.

       -larchive
       --library=archive
	   Add archive file archive to the list	of files to link.  This	option
	   may	be used	any number of times.  ld will search its path-list for
	   occurrences of "libarchive.a" for every archive specified.

	   On systems which support shared libraries, ld may also  search  for
	   libraries  with  extensions	other than ".a".  Specifically,	on ELF
	   and SunOS systems, ld will search a directory for a library with an
	   extension  of  ".so"	 before	searching for one with an extension of
	   ".a".  By convention, a ".so" extension indicates a shared library.

	   The	linker will search an archive only once, at the	location where
	   it is specified on the command line.	 If the	archive	defines	a sym-
	   bol	which  was  undefined in some object which appeared before the
	   archive on the command line,	the linker will	include	the  appropri-
	   ate	file(s)	 from the archive.  However, an	undefined symbol in an
	   object appearing later on the  command  line	 will  not  cause  the
	   linker to search the	archive	again.

	   See	the -( option for a way	to force the linker to search archives
	   multiple times.

	   You may list	the same archive multiple times	on the command line.

	   This	type of	archive	searching is standard for Unix linkers.	  How-
	   ever,  if  you  are using ld	on AIX,	note that it is	different from
	   the behaviour of the	AIX linker.

       -Lsearchdir
       --library-path=searchdir
	   Add path searchdir to the list of paths that	ld will	search for ar-
	   chive  libraries  and  ld control scripts.  You may use this	option
	   any number of times.	 The directories are searched in the order  in
	   which  they	are specified on the command line.  Directories	speci-
	   fied	on the command line are	searched before	the  default  directo-
	   ries.   All	-L  options apply to all -l options, regardless	of the
	   order in which the options appear.

	   The default set of paths searched (without being specified with -L)
	   depends on which emulation mode ld is using,	and in some cases also
	   on how it was configured.

	   The paths  can  also	 be  specified	in  a  link  script  with  the
	   "SEARCH_DIR"	 command.  Directories specified this way are searched
	   at the point	in which the linker  script  appears  in  the  command
	   line.

       -memulation
	   Emulate  the	 emulation  linker.  You can list the available	emula-
	   tions with the --verbose or -V options.

	   If the -m option is not used,  the  emulation  is  taken  from  the
	   "LDEMULATION" environment variable, if that is defined.

	   Otherwise,  the  default  emulation depends upon how	the linker was
	   configured.

       -M
       --print-map
	   Print a link	map to the  standard  output.	A  link	 map  provides
	   information about the link, including the following:

	   o   Where object files and symbols are mapped into memory.

	   o   How common symbols are allocated.

	   o   All archive members included in the link, with a	mention	of the
	       symbol which caused the archive member to be brought in.

       -n
       --nmagic
	   Turn	off page  alignment  of	 sections,  and	 mark  the  output  as
	   "NMAGIC" if possible.

       -N
       --omagic
	   Set	the text and data sections to be readable and writable.	 Also,
	   do not page-align the data segment.	If the output format  supports
	   Unix	style magic numbers, mark the output as	"OMAGIC".

       -o output
       --output=output
	   Use	output	as  the	 name  for the program produced	by ld; if this
	   option is not specified, the	name a.out is used  by	default.   The
	   script command "OUTPUT" can also specify the	output file name.

       -O level
	   If  level  is  a  numeric values greater than zero ld optimizes the
	   output.  This might take significantly longer and therefore	proba-
	   bly should only be enabled for the final binary.

       -q
       --emit-relocs
	   Leave  relocation  sections and contents in fully linked exececuta-
	   bles.  Post link analysis and  optimization	tools  may  need  this
	   information	in  order to perform correct modifications of executa-
	   bles.  This results in larger executables.

	   This	option is currently only supported on ELF platforms.

       -r
       --relocateable
	   Generate relocatable	output---i.e., generate	an  output  file  that
	   can	in  turn  serve	 as input to ld.  This is often	called partial
	   linking.  As	a side effect, in environments that  support  standard
	   Unix	 magic	numbers, this option also sets the output file's magic
	   number to "OMAGIC".	If this	option is not specified,  an  absolute
	   file	 is produced.  When linking C++	programs, this option will not
	   resolve references to constructors; to do that, use -Ur.

	   When	an input file does not have the	 same  format  as  the	output
	   file, partial linking is only supported if that input file does not
	   contain any relocations.  Different output formats can have further
	   restrictions; for example some "a.out"-based	formats	do not support
	   partial linking with	input files in other formats at	all.

	   This	option does the	same thing as -i.

       -R filename
       --just-symbols=filename
	   Read	symbol names and their addresses from  filename,  but  do  not
	   relocate  it	 or include it in the output.  This allows your	output
	   file	to refer symbolically to absolute locations of memory  defined
	   in other programs.  You may use this	option more than once.

	   For	compatibility with other ELF linkers, if the -R	option is fol-
	   lowed by a directory	name, rather than a file name, it  is  treated
	   as the -rpath option.

       -s
       --strip-all
	   Omit	all symbol information from the	output file.

       -S
       --strip-debug
	   Omit	 debugger  symbol  information	(but not all symbols) from the
	   output file.

       -t
       --trace
	   Print the names of the input	files as ld processes them.

       -T scriptfile
       --script=scriptfile
	   Use scriptfile as the linker	script.	  This	script	replaces  ld's
	   default  linker  script  (rather than adding	to it),	so commandfile
	   must	specify	everything necessary  to  describe  the	 output	 file.
	   If  scriptfile  does	not exist in the current directory, "ld" looks
	   for it in the directories specified by any  preceding  -L  options.
	   Multiple -T options accumulate.

       -u symbol
       --undefined=symbol
	   Force  symbol to be entered in the output file as an	undefined sym-
	   bol.	 Doing this may, for example, trigger  linking	of  additional
	   modules from	standard libraries.  -u	may be repeated	with different
	   option arguments  to	 enter	additional  undefined  symbols.	  This
	   option is equivalent	to the "EXTERN"	linker script command.

       -Ur For	anything other than C++	programs, this option is equivalent to
	   -r: it generates relocatable	output---i.e., an output file that can
	   in  turn serve as input to ld.  When	linking	C++ programs, -Ur does
	   resolve references to constructors, unlike -r.  It does not work to
	   use	-Ur  on	 files	that were themselves linked with -Ur; once the
	   constructor table has been built, it	cannot be added	to.   Use  -Ur
	   only	for the	last partial link, and -r for the others.

       --unique[=SECTION]
	   Creates  a separate output section for every	input section matching
	   SECTION, or if the optional wildcard	SECTION	argument  is  missing,
	   for	every  orphan  input  section.	 An  orphan section is one not
	   specifically	mentioned in a linker script.  You may use this	option
	   multiple times on the command line;	It prevents the	normal merging
	   of input sections with the same  name,  overriding  output  section
	   assignments in a linker script.

       -v
       --version
       -V  Display  the	 version  number for ld.  The -V option	also lists the
	   supported emulations.

       -x
       --discard-all
	   Delete all local symbols.

       -X
       --discard-locals
	   Delete all temporary	local symbols.	For most targets, this is  all
	   local symbols whose names begin with	L.

       -y symbol
       --trace-symbol=symbol
	   Print  the  name of each linked file	in which symbol	appears.  This
	   option may be given any number of times.  On	 many  systems	it  is
	   necessary to	prepend	an underscore.

	   This	 option	 is  useful  when you have an undefined	symbol in your
	   link	but don't know where the reference is coming from.

       -Y path
	   Add path to the default library search path.	  This	option	exists
	   for Solaris compatibility.

       -z keyword
	   The	recognized  keywords are "initfirst", "interpose", "loadfltr",
	   "nodefaultlib", "nodelete", "nodlopen", "nodump", "now",  "origin",
	   "combreloc",	 "nocombreloc"	and "nocopyreloc".  The	other keywords
	   are ignored for Solaris compatibility. "initfirst" marks the	object
	   to  be  initialized	first  at  runtime  before  any	other objects.
	   "interpose" marks the  object  that	its  symbol  table  interposes
	   before all symbols but the primary executable. "loadfltr" marks the
	   object that	its  filtees  be  processed  immediately  at  runtime.
	   "nodefaultlib" marks	the object that	the search for dependencies of
	   this	 object	 will  ignore  any  default  library   search	paths.
	   "nodelete"  marks  the  object  shouldn't  be  unloaded at runtime.
	   "nodlopen" marks the	object not available  to  "dlopen".   "nodump"
	   marks  the  object  can not be dumped by "dldump".  "now" marks the
	   object with the  non-lazy  runtime  binding.	  "origin"  marks  the
	   object  may	contain	 $ORIGIN.  "defs" disallows undefined symbols.
	   "muldefs" allows multiple definitions.  "combreloc" combines	multi-
	   ple	reloc  sections	 and  sorts them to make dynamic symbol	lookup
	   caching possible.  "nocombreloc" disables multiple  reloc  sections
	   combining.  "nocopyreloc" disables production of copy relocs.

       -( archives -)
       --start-group archives --end-group
	   The archives	should be a list of archive files.  They may be	either
	   explicit file names,	or -l options.

	   The specified archives are searched repeatedly until	no  new	 unde-
	   fined  references  are  created.   Normally,	an archive is searched
	   only	once in	the order that it is specified on  the	command	 line.
	   If  a symbol	in that	archive	is needed to resolve an	undefined sym-
	   bol referred	to by an object	in an archive that  appears  later  on
	   the command line, the linker	would not be able to resolve that ref-
	   erence.  By grouping	the archives, they all be searched  repeatedly
	   until all possible references are resolved.

	   Using  this	option has a significant performance cost.  It is best
	   to use it only  when	 there	are  unavoidable  circular  references
	   between two or more archives.

       -assert keyword
	   This	option is ignored for SunOS compatibility.

       -Bdynamic
       -dy
       -call_shared
	   Link	 against  dynamic libraries.  This is only meaningful on plat-
	   forms for which shared libraries are	 supported.   This  option  is
	   normally  the default on such platforms.  The different variants of
	   this	option are for compatibility with various  systems.   You  may
	   use	this  option  multiple	times  on the command line: it affects
	   library searching for -l options which follow it.

       -Bgroup
	   Set the "DF_1_GROUP"	flag in	the "DT_FLAGS_1" entry in the  dynamic
	   section.   This causes the runtime linker to	handle lookups in this
	   object and its dependencies to be performed only inside the	group.
	   --no-undefined  is  implied.	 This option is	only meaningful	on ELF
	   platforms which support shared libraries.

       -Bstatic
       -dn
       -non_shared
       -static
	   Do not link against shared libraries.  This is only	meaningful  on
	   platforms  for which	shared libraries are supported.	 The different
	   variants of this option are for compatibility with various systems.
	   You	may  use  this	option	multiple times on the command line: it
	   affects library searching for -l options which follow it.

       -Bsymbolic
	   When	creating a shared library, bind	references to  global  symbols
	   to  the definition within the shared	library, if any.  Normally, it
	   is possible for a program linked against a shared library to	 over-
	   ride	the definition within the shared library.  This	option is only
	   meaningful on ELF platforms which support shared libraries.

       --check-sections
       --no-check-sections
	   Asks	the linker not to check	section	addresses after	they have been
	   assigned  to	 see  if there any overlaps.  Normally the linker will
	   perform this	check, and if it finds any overlaps  it	 will  produce
	   suitable error messages.  The linker	does know about, and does make
	   allowances for sections in overlays.	 The default behaviour can  be
	   restored by using the command line switch --check-sections.

       --cref
	   Output a cross reference table.  If a linker	map file is being gen-
	   erated, the cross reference table is	printed	to the map file.  Oth-
	   erwise, it is printed on the	standard output.

	   The	format of the table is intentionally simple, so	that it	may be
	   easily processed by a script	if necessary.  The symbols are printed
	   out,	 sorted	 by  name.   For  each symbol, a list of file names is
	   given.  If the symbol is defined, the  first	 file  listed  is  the
	   location of the definition.	The remaining files contain references
	   to the symbol.

       --no-define-common
	   This	option inhibits	the assignment of addresses to common symbols.
	   The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.

	   The --no-define-common option allows	 decoupling  the  decision  to
	   assign  addresses  to  Common symbols from the choice of the	output
	   file	type; otherwise	a non-Relocatable output type forces assigning
	   addresses  to Common	symbols.  Using	--no-define-common allows Com-
	   mon symbols that  are  referenced  from  a  shared  library	to  be
	   assigned  addresses	only in	the main program.  This	eliminates the
	   unused duplicate space in the shared	library, and also prevents any
	   possible confusion over resolving to	the wrong duplicate when there
	   are many dynamic modules with specialized search paths for  runtime
	   symbol resolution.

       --defsym	symbol=expression
	   Create  a global symbol in the output file, containing the absolute
	   address given by expression.	 You may use this option as many times
	   as  necessary  to  define  multiple symbols in the command line.  A
	   limited form	of arithmetic is supported for the expression in  this
	   context:  you  may  give  a	hexadecimal constant or	the name of an
	   existing symbol, or use "+" and "-" to add or subtract  hexadecimal
	   constants or	symbols.  If you need more elaborate expressions, con-
	   sider using the linker command language from	a script.  Note: there
	   should  be  no white	space between symbol, the equals sign (``=''),
	   and expression.

       --demangle[=style]
       --no-demangle
	   These options control whether to demangle  symbol  names  in	 error
	   messages and	other output.  When the	linker is told to demangle, it
	   tries to present symbol names in  a	readable  fashion:  it	strips
	   leading underscores if they are used	by the object file format, and
	   converts C++	mangled	symbol names into user readable	 names.	  Dif-
	   ferent  compilers  have  different  mangling	 styles.  The optional
	   demangling style argument can be  used  to  choose  an  appropriate
	   demangling  style  for  your	compiler.  The linker will demangle by
	   default unless the environment variable COLLECT_NO_DEMANGLE is set.
	   These options may be	used to	override the default.

       --dynamic-linker	file
	   Set	the  name of the dynamic linker.  This is only meaningful when
	   generating dynamically linked ELF executables.  The default dynamic
	   linker is normally correct; don't use this unless you know what you
	   are doing.

       --embedded-relocs
	   This	option is only meaningful when linking MIPS embedded PIC code,
	   generated  by  the  -membedded-pic  option  to the GNU compiler and
	   assembler.  It causes the linker to create a	 table	which  may  be
	   used	 at runtime to relocate	any data which was statically initial-
	   ized	to pointer values.  See	the  code  in  testsuite/ld-empic  for
	   details.

       --fatal-warnings
	   Treat all warnings as errors.

       --force-exe-suffix
	   Make	sure that an output file has a .exe suffix.

	   If  a  successfully	built fully linked output file does not	have a
	   ".exe" or ".dll" suffix, this option	forces the linker to copy  the
	   output  file	 to  one  of  the same name with a ".exe" suffix. This
	   option  is  useful  when  using  unmodified	Unix  makefiles	 on  a
	   Microsoft Windows host, since some versions of Windows won't	run an
	   image unless	it ends	in a ".exe" suffix.

       --no-gc-sections
       --gc-sections
	   Enable garbage collection of	unused input sections.	It is  ignored
	   on  targets	that  do  not support this option.  This option	is not
	   compatible with -r, nor should it be	 used  with  dynamic  linking.
	   The	default	 behaviour (of not performing this garbage collection)
	   can be restored by specifying --no-gc-sections on the command line.

       --help
	   Print  a summary of the command-line	options	on the standard	output
	   and exit.

       --target-help
	   Print a summary of all target specific options on the standard out-
	   put and exit.

       -Map mapfile
	   Print  a  link map to the file mapfile.  See	the description	of the
	   -M option, above.

       --no-keep-memory
	   ld normally optimizes for speed over	memory usage  by  caching  the
	   symbol  tables  of  input files in memory.  This option tells ld to
	   instead optimize for	memory usage, by rereading the	symbol	tables
	   as  necessary.  This	may be required	if ld runs out of memory space
	   while linking a large executable.

       --no-undefined
       -z defs
	   Normally when creating a  non-symbolic  shared  library,  undefined
	   symbols  are	allowed	and left to be resolved	by the runtime loader.
	   These options disallows such	undefined symbols.

       --allow-multiple-definition
       -z muldefs
	   Normally when a symbol is defined multiple times, the  linker  will
	   report  a fatal error. These	options	allow multiple definitions and
	   the first definition	will be	used.

       --allow-shlib-undefined
	   Allow undefined symbols in shared objects even  when	--no-undefined
	   is  set.  The  net result will be that undefined symbols in regular
	   objects will	still trigger  an  error,  but	undefined  symbols  in
	   shared objects will be ignored.  The	implementation of no_undefined
	   makes the assumption	that the runtime linker	will  choke  on	 unde-
	   fined  symbols.   However there is at least one system (BeOS) where
	   undefined symbols in	shared libraries is normal  since  the	kernel
	   patches  them  at load time to select which function	is most	appro-
	   priate for the current architecture.	 I.E.  dynamically  select  an
	   appropriate memset function.	 Apparently it is also normal for HPPA
	   shared libraries to have undefined symbols.

       --no-undefined-version
	   Normally when a symbol has an undefined version,  the  linker  will
	   ignore it. This option disallows symbols with undefined version and
	   a fatal error will be issued	instead.

       --no-warn-mismatch
	   Normally ld will give an error if you try to	 link  together	 input
	   files  that	are  mismatched	 for some reason, perhaps because they
	   have	been compiled for different processors or for different	 endi-
	   annesses.  This option tells	ld that	it should silently permit such
	   possible errors.  This option should	only be	 used  with  care,  in
	   cases when you have taken some special action that ensures that the
	   linker errors are inappropriate.

       --no-whole-archive
	   Turn	off the	effect of the --whole-archive  option  for  subsequent
	   archive files.

       --noinhibit-exec
	   Retain  the	executable  output  file  whenever it is still usable.
	   Normally, the linker	will not produce an output file	if it  encoun-
	   ters	 errors	 during	 the link process; it exits without writing an
	   output file when it issues any error	whatsoever.

       -nostdlib
	   Only	search library directories explicitly specified	on the command
	   line.   Library  directories	specified in linker scripts (including
	   linker scripts specified on the command line) are ignored.

       --oformat output-format
	   ld may be configured	to support more	than one kind of object	 file.
	   If your ld is configured this way, you can use the --oformat	option
	   to specify the binary format	for the	output object file.  Even when
	   ld  is  configured to support alternative object formats, you don't
	   usually need	to specify this, as ld should be configured to produce
	   as  a  default output format	the most usual format on each machine.
	   output-format is a text string, the name  of	 a  particular	format
	   supported by	the BFD	libraries.  (You can list the available	binary
	   formats with	objdump	-i.)  The script command  "OUTPUT_FORMAT"  can
	   also	specify	the output format, but this option overrides it.

       -qmagic
	   This	option is ignored for Linux compatibility.

       -Qy This	option is ignored for SVR4 compatibility.

       --relax
	   An option with machine dependent effects.  This option is only sup-
	   ported on a few targets.

	   On some platforms, the --relax option performs global optimizations
	   that	 become	 possible  when	 the linker resolves addressing	in the
	   program, such  as  relaxing	address	 modes	and  synthesizing  new
	   instructions	in the output object file.

	   On  some  platforms	these  link time global	optimizations may make
	   symbolic debugging of the resulting executable impossible.  This is
	   known  to be	the case for the Matsushita MN10200 and	MN10300	family
	   of processors.

	   On platforms	where this is not supported, --relax is	accepted,  but
	   ignored.

       --retain-symbols-file filename
	   Retain only the symbols listed in the file filename,	discarding all
	   others.  filename is	simply a flat file, with one symbol  name  per
	   line.   This	 option	 is especially useful in environments (such as
	   VxWorks) where a large global symbol	table  is  accumulated	gradu-
	   ally, to conserve run-time memory.

	   --retain-symbols-file  does	not discard undefined symbols, or sym-
	   bols	needed for relocations.

	   You may only	specify	 --retain-symbols-file	once  in  the  command
	   line.  It overrides -s and -S.

       -rpath dir
	   Add	a  directory to	the runtime library search path.  This is used
	   when	linking	an ELF executable with	shared	objects.   All	-rpath
	   arguments  are concatenated and passed to the runtime linker, which
	   uses	them to	locate shared objects at runtime.  The	-rpath	option
	   is  also  used  when	 locating  shared  objects which are needed by
	   shared objects explicitly included in the link; see the description
	   of  the  -rpath-link	option.	 If -rpath is not used when linking an
	   ELF	executable,  the  contents   of	  the	environment   variable
	   "LD_RUN_PATH" will be used if it is defined.

	   The -rpath option may also be used on SunOS.	 By default, on	SunOS,
	   the linker will form	a runtime search  patch	 out  of  all  the  -L
	   options  it	is  given.   If	 a  -rpath option is used, the runtime
	   search path will be formed exclusively using	 the  -rpath  options,
	   ignoring  the -L options.  This can be useful when using gcc, which
	   adds	many -L	options	which may be on	NFS mounted filesystems.

	   For compatibility with other	ELF linkers, if	the -R option is  fol-
	   lowed  by  a	directory name,	rather than a file name, it is treated
	   as the -rpath option.

       -rpath-link DIR
	   When	using ELF or SunOS, one	shared library	may  require  another.
	   This	happens	when an	"ld -shared" link includes a shared library as
	   one of the input files.

	   When	 the  linker  encounters  such	a  dependency  when  doing   a
	   non-shared,	non-relocatable	 link,	it  will  automatically	try to
	   locate the required shared library and include it in	the  link,  if
	   it  is  not	included  explicitly.  In such a case, the -rpath-link
	   option specifies the	first  set  of	directories  to	 search.   The
	   -rpath-link option may specify a sequence of	directory names	either
	   by specifying a list	of names separated by colons, or by  appearing
	   multiple times.

	   This	 option	should be used with caution as it overrides the	search
	   path	that may have been hard	compiled into  a  shared  library.  In
	   such	 a  case  it  is  possible  to use unintentionally a different
	   search path than the	runtime	linker would do.

	   The linker uses the	following  search  paths  to  locate  required
	   shared libraries.

	   1.  Any directories specified by -rpath-link	options.

	   2.  Any  directories	 specified  by -rpath options.	The difference
	       between -rpath and -rpath-link is that directories specified by
	       -rpath  options are included in the executable and used at run-
	       time, whereas the -rpath-link option is only effective at  link
	       time. It	is for the native linker only.

	   3.  On  an  ELF system, if the -rpath and "rpath-link" options were
	       not used, search	 the  contents	of  the	 environment  variable
	       "LD_RUN_PATH". It is for	the native linker only.

	   4.  On  SunOS, if the -rpath	option was not used, search any	direc-
	       tories specified	using -L options.

	   5.  For a native linker, the	contents of the	 environment  variable
	       "LD_LIBRARY_PATH".

	   6.  For  a  native  ELF  linker, the	directories in "DT_RUNPATH" or
	       "DT_RPATH"  of  a  shared  library  are	searched  for	shared
	       libraries  needed  by it. The "DT_RPATH"	entries	are ignored if
	       "DT_RUNPATH" entries exist.

	   7.  The default directories,	normally /lib and /usr/lib.

	   8.  For  a  native  linker  on  an  ELF   system,   if   the	  file
	       /etc/ld.so.conf	exists,	 the list of directories found in that
	       file.

	   If the required shared library is not found,	the linker will	 issue
	   a warning and continue with the link.

       -shared
       -Bshareable
	   Create  a shared library.  This is currently	only supported on ELF,
	   XCOFF and SunOS platforms.  On SunOS, the linker will automatically
	   create  a shared library if the -e option is	not used and there are
	   undefined symbols in	the link.

       --sort-common
	   This	option tells ld	to sort	the common symbols  by	size  when  it
	   places them in the appropriate output sections.  First come all the
	   one byte symbols, then all the two byte, then all  the  four	 byte,
	   and	then everything	else.  This is to prevent gaps between symbols
	   due to alignment constraints.

       --split-by-file [size]
	   Similar to --split-by-reloc but creates a new  output  section  for
	   each	input file when	size is	reached.  size defaults	to a size of 1
	   if not given.

       --split-by-reloc	[count]
	   Tries to creates extra sections in the output file so that no  sin-
	   gle	output	section	 in  the file contains more than count reloca-
	   tions.  This	is useful when generating huge relocatable  files  for
	   downloading	into  certain  real  time kernels with the COFF	object
	   file	format;	since COFF cannot represent more  than	65535  reloca-
	   tions  in  a	single section.	 Note that this	will fail to work with
	   object file formats which do	not support arbitrary  sections.   The
	   linker  will	not split up individual	input sections for redistribu-
	   tion, so if a single	input section contains more than count reloca-
	   tions one output section will contain that many relocations.	 count
	   defaults to a value of 32768.

       --stats
	   Compute and display statistics about	the operation of  the  linker,
	   such	as execution time and memory usage.

       --traditional-format
	   For	some  targets, the output of ld	is different in	some ways from
	   the output of some existing linker.	This switch requests ld	to use
	   the traditional format instead.

	   For	example, on SunOS, ld combines duplicate entries in the	symbol
	   string table.  This can reduce the size of an output	file with full
	   debugging information by over 30 percent.  Unfortunately, the SunOS
	   "dbx" program can not read the  resulting  program  ("gdb"  has  no
	   trouble).   The --traditional-format	switch tells ld	to not combine
	   duplicate entries.

       --section-start sectionname=org
	   Locate a section in the output file at the absolute	address	 given
	   by  org.   You  may	use  this option as many times as necessary to
	   locate multiple sections in the command line.  org must be a	single
	   hexadecimal	integer; for compatibility with	other linkers, you may
	   omit	the leading 0x usually	associated  with  hexadecimal  values.
	   Note:  there	 should	 be  no	 white	space between sectionname, the
	   equals sign (``=''),	and org.

       -Tbss org
       -Tdata org
       -Ttext org
	   Use org as the  starting  address  for---respectively---the	"bss",
	   "data",  or	the  "text" segment of the output file.	 org must be a
	   single hexadecimal integer; for compatibility with  other  linkers,
	   you	may  omit  the	leading	0x usually associated with hexadecimal
	   values.

       --dll-verbose
       --verbose
	   Display the version number for ld and list  the  linker  emulations
	   supported.	Display	 which	input  files can and cannot be opened.
	   Display the linker script being used	by the linker.

       --version-script=version-scriptfile
	   Specify the name of a version script	to the linker.	This is	 typi-
	   cally  used	when  creating	shared libraries to specify additional
	   information about the version heirarchy for the library being  cre-
	   ated.   This	 option	is only	meaningful on ELF platforms which sup-
	   port	shared libraries.

       --warn-common
	   Warn	when a common symbol is	combined with another common symbol or
	   with	 a symbol definition.  Unix linkers allow this somewhat	sloppy
	   practice, but linkers on some other operating systems do not.  This
	   option  allows you to find potential	problems from combining	global
	   symbols.  Unfortunately, some C libraries use this practice,	so you
	   may	get some warnings about	symbols	in the libraries as well as in
	   your	programs.

	   There are three kinds of global  symbols,  illustrated  here	 by  C
	   examples:

	   int i = 1;
	       A definition, which goes	in the initialized data	section	of the
	       output file.

	   extern int i;
	       An undefined reference, which does not allocate	space.	 There
	       must be either a	definition or a	common symbol for the variable
	       somewhere.

	   int i;
	       A common	symbol.	 If there are only (one	or more)  common  sym-
	       bols  for a variable, it	goes in	the uninitialized data area of
	       the output file.	 The linker merges multiple common symbols for
	       the same	variable into a	single symbol.	If they	are of differ-
	       ent sizes, it picks the largest size.  The linker turns a  com-
	       mon  symbol into	a declaration, if there	is a definition	of the
	       same variable.

	   The --warn-common option can	produce	five kinds of warnings.	  Each
	   warning consists of a pair of lines:	the first describes the	symbol
	   just	encountered, and the  second  describes	 the  previous	symbol
	   encountered	with  the  same	 name.	One or both of the two symbols
	   will	be a common symbol.

	   1.  Turning a common	symbol into  a	reference,  because  there  is
	       already a definition for	the symbol.

		       <file>(<section>): warning: common of `<symbol>'
			  overridden by	definition
		       <file>(<section>): warning: defined here

	   2.  Turning a common	symbol into a reference, because a later defi-
	       nition for the symbol is	encountered.  This is the same as  the
	       previous	 case,	except	that  the symbols are encountered in a
	       different order.

		       <file>(<section>): warning: definition of `<symbol>'
			  overriding common
		       <file>(<section>): warning: common is here

	   3.  Merging a common	symbol with a previous same-sized common  sym-
	       bol.

		       <file>(<section>): warning: multiple common
			  of `<symbol>'
		       <file>(<section>): warning: previous common is here

	   4.  Merging a common	symbol with a previous larger common symbol.

		       <file>(<section>): warning: common of `<symbol>'
			  overridden by	larger common
		       <file>(<section>): warning: larger common is here

	   5.  Merging	a common symbol	with a previous	smaller	common symbol.
	       This is the same	as the previous	case, except that the  symbols
	       are encountered in a different order.

		       <file>(<section>): warning: common of `<symbol>'
			  overriding smaller common
		       <file>(<section>): warning: smaller common is here

       --warn-constructors
	   Warn	 if any	global constructors are	used.  This is only useful for
	   a few object	file formats.  For  formats  like  COFF	 or  ELF,  the
	   linker can not detect the use of global constructors.

       --warn-multiple-gp
	   Warn	 if  multiple global pointer values are	required in the	output
	   file.  This is only meaningful for certain processors, such as  the
	   Alpha.  Specifically, some processors put large-valued constants in
	   a special section.  A special register (the global pointer)	points
	   into	 the  middle  of this section, so that constants can be	loaded
	   efficiently via a base-register relative  addressing	 mode.	 Since
	   the	offset	in base-register relative mode is fixed	and relatively
	   small (e.g.,	16 bits), this limits the maximum size of the constant
	   pool.  Thus,	in large programs, it is often necessary to use	multi-
	   ple global pointer values in	order to be able to address all	possi-
	   ble	constants.  This option	causes a warning to be issued whenever
	   this	case occurs.

       --warn-once
	   Only	warn once for each undefined symbol, rather than once per mod-
	   ule which refers to it.

       --warn-section-align
	   Warn	 if  the  address  of  an output section is changed because of
	   alignment.  Typically, the alignment	will be	set by an  input  sec-
	   tion.  The address will only	be changed if it not explicitly	speci-
	   fied; that is, if the "SECTIONS" command does not specify  a	 start
	   address for the section.

       --whole-archive
	   For	 each	archive	 mentioned  on	the  command  line  after  the
	   --whole-archive option, include every object	file in	the archive in
	   the link, rather than searching the archive for the required	object
	   files.  This	is normally used to turn an archive file into a	shared
	   library,  forcing  every  object  to	 be  included in the resulting
	   shared library.  This option	may be used more than once.

	   Two notes when using	this option from gcc: First, gcc doesn't  know
	   about  this option, so you have to use -Wl,-whole-archive.  Second,
	   don't forget	to use -Wl,-no-whole-archive after your	 list  of  ar-
	   chives,  because gcc	will add its own list of archives to your link
	   and you may not want	this flag to affect those as well.

       --wrap symbol
	   Use a wrapper function for symbol.  Any undefined reference to sym-
	   bol	will  be resolved to "__wrap_symbol".  Any undefined reference
	   to "__real_symbol" will be resolved to symbol.

	   This	can be used to provide a wrapper for a system  function.   The
	   wrapper function should be called "__wrap_symbol".  If it wishes to
	   call	the system function, it	should call "__real_symbol".

	   Here	is a trivial example:

		   void	*
		   __wrap_malloc (int c)
		   {
		     printf ("malloc called with %ld\n", c);
		     return __real_malloc (c);
		   }

	   If you link other code with this file using --wrap malloc, then all
	   calls  to  "malloc" will call the function "__wrap_malloc" instead.
	   The call to "__real_malloc" in "__wrap_malloc" will call  the  real
	   "malloc" function.

	   You may wish	to provide a "__real_malloc" function as well, so that
	   links without the --wrap option will	succeed.  If you do this,  you
	   should  not	put the	definition of "__real_malloc" in the same file
	   as "__wrap_malloc"; if you do, the assembler	may resolve  the  call
	   before the linker has a chance to wrap it to	"malloc".

       --enable-new-dtags
       --disable-new-dtags
	   This	 linker	 can create the	new dynamic tags in ELF. But the older
	   ELF	 systems   may	 not   understand   them.   If	 you   specify
	   --enable-new-dtags, the dynamic tags	will be	created	as needed.  If
	   you specify --disable-new-dtags, no new dynamic tags	will  be  cre-
	   ated.  By  default, the new dynamic tags are	not created. Note that
	   those options are only available for	ELF systems.

       The i386	PE linker supports the -shared option, which causes the	output
       to  be  a  dynamically  linked  library	(DLL) instead of a normal exe-
       cutable.	 You should name the output "*.dll" when you use this  option.
       In  addition,  the  linker  fully  supports the standard	"*.def"	files,
       which may be specified on the linker command line like an  object  file
       (in fact, it should precede archives it exports symbols from, to	ensure
       that they get linked in,	just like a normal object file).

       In addition to the options common to all	targets, the  i386  PE	linker
       support	additional  command line options that are specific to the i386
       PE target.  Options that	take values may	be separated from their	values
       by either a space or an equals sign.

       --add-stdcall-alias
	   If  given, symbols with a stdcall suffix (@nn) will be exported as-
	   is and also with the	suffix stripped.

       --base-file file
	   Use file as the name	of a file in which to save the base  addresses
	   of all the relocations needed for generating	DLLs with dlltool.

       --dll
	   Create  a  DLL  instead  of a regular executable.  You may also use
	   -shared or specify a	"LIBRARY" in a given ".def" file.

       --enable-stdcall-fixup
       --disable-stdcall-fixup
	   If the link finds a symbol that it cannot resolve, it will  attempt
	   to  do  "fuzzy  linking" by looking for another defined symbol that
	   differs only	in the format of the symbol name  (cdecl  vs  stdcall)
	   and will resolve that symbol	by linking to the match.  For example,
	   the undefined  symbol  "_foo"  might	 be  linked  to	 the  function
	   "_foo@12", or the undefined symbol "_bar@16"	might be linked	to the
	   function "_bar".  When the linker does this,	it prints  a  warning,
	   since  it normally should have failed to link, but sometimes	import
	   libraries generated from third-party	dlls may need this feature  to
	   be  usable.	If you specify --enable-stdcall-fixup, this feature is
	   fully enabled and warnings are not printed.	If you specify	--dis-
	   able-stdcall-fixup,	this  feature  is disabled and such mismatches
	   are considered to be	errors.

       --export-all-symbols
	   If given, all global	symbols	in the objects used  to	 build	a  DLL
	   will	 be  exported  by  the	DLL.  Note that	this is	the default if
	   there otherwise wouldn't be any exported symbols.  When symbols are
	   explicitly  exported	via DEF	files or implicitly exported via func-
	   tion	attributes, the	default	is to not export anything else	unless
	   this	 option	is given.  Note	that the symbols "DllMain@12", "DllEn-
	   tryPoint@0",	"DllMainCRTStartup@12",	and "impure_ptr" will  not  be
	   automatically  exported.   Also,  symbols  imported from other DLLs
	   will	not be re-exported, nor	 will  symbols	specifying  the	 DLL's
	   internal  layout  such  as  those beginning with "_head_" or	ending
	   with	"_iname".  In addition,	no symbols from	"libgcc",  "libstd++",
	   "libmingw32",  or  "crtX.o"	will be	exported.  Symbols whose names
	   begin with "__rtti_"	or "__builtin_"	will not be exported, to  help
	   with	 C++ DLLs.  Finally, there is an extensive list	of cygwin-pri-
	   vate	symbols	that are not exported (obviously, this applies on when
	   building  DLLs  for	cygwin	targets).   These cygwin-excludes are:
	   "_cygwin_dll_entry@12",  "_cygwin_crt0_common@8",  "_cygwin_noncyg-
	   win_dll_entry@12",  "_fmode",  "_impure_ptr",  "cygwin_attach_dll",
	   "cygwin_premain0",  "cygwin_premain1",   "cygwin_premain2",	 "cyg-
	   win_premain3", and "environ".

       --exclude-symbols symbol,symbol,...
	   Specifies  a	 list  of  symbols  which  should not be automatically
	   exported.  The symbol names may be delimited	by commas or colons.

       --exclude-libs lib,lib,...
	   Specifies a list of archive libraries from which symbols should not
	   be  automatically  exported.	 The library names may be delimited by
	   commas or colons.  Specifying "--exclude-libs ALL" excludes symbols
	   in  all archive libraries from automatic export. Symbols explicitly
	   listed in a .def  file  are	still  exported,  regardless  of  this
	   option.

       --file-alignment
	   Specify the file alignment.	Sections in the	file will always begin
	   at file offsets which are multiples of this number.	This  defaults
	   to 512.

       --heap reserve
       --heap reserve,commit
	   Specify  the	amount of memory to reserve (and optionally commit) to
	   be used as heap for this program.  The default is 1Mb reserved,  4K
	   committed.

       --image-base value
	   Use	value as the base address of your program or dll.  This	is the
	   lowest memory location that will be used when your program  or  dll
	   is  loaded.	To reduce the need to relocate and improve performance
	   of your dlls, each should have a unique base	address	and not	 over-
	   lap	any  other dlls.  The default is 0x400000 for executables, and
	   0x10000000 for dlls.

       --kill-at
	   If given, the stdcall suffixes (@nn)	will be	stripped from  symbols
	   before they are exported.

       --major-image-version value
	   Sets	the major number of the	"image version".  Defaults to 1.

       --major-os-version value
	   Sets	the major number of the	"os version".  Defaults	to 4.

       --major-subsystem-version value
	   Sets	the major number of the	"subsystem version".  Defaults to 4.

       --minor-image-version value
	   Sets	the minor number of the	"image version".  Defaults to 0.

       --minor-os-version value
	   Sets	the minor number of the	"os version".  Defaults	to 0.

       --minor-subsystem-version value
	   Sets	the minor number of the	"subsystem version".  Defaults to 0.

       --output-def file
	   The	linker will create the file file which will contain a DEF file
	   corresponding to the	DLL the	linker is generating.  This  DEF  file
	   (which  should  be  called "*.def") may be used to create an	import
	   library with	"dlltool" or may be used as a reference	 to  automati-
	   cally or implicitly exported	symbols.

       --out-implib file
	   The	linker	will create the	file file which	will contain an	import
	   lib corresponding to	the DLL	the linker is generating. This	import
	   lib	(which should be called	"*.dll.a" or "*.a" may be used to link
	   clients against the generated DLL; this behavior makes it  possible
	   to skip a separate "dlltool"	import library creation	step.

       --enable-auto-image-base
	   Automatically  choose the image base	for DLLs, unless one is	speci-
	   fied	using the "--image-base" argument.  By using a hash  generated
	   from	the dllname to create unique image bases for each DLL, in-mem-
	   ory collisions and relocations which	can  delay  program  execution
	   are avoided.

       --disable-auto-image-base
	   Do  not automatically generate a unique image base.	If there is no
	   user-specified image	base ("--image-base") then  use	 the  platform
	   default.

       --dll-search-prefix string
	   When	 linking  dynamically  to  a  dll without an import library, i
	   search for "<string><basename>.dll"	in  preference	to  "lib<base-
	   name>.dll".	This  behavior	allows	easy  distinction between DLLs
	   built for the various "subplatforms":  native,  cygwin,  uwin,  pw,
	   etc.	  For  instance,  cygwin DLLs typically	use "--dll-search-pre-
	   fix=cyg".

       --enable-auto-import
	   Do sophisticated linking of "_symbol" to "__imp__symbol"  for  DATA
	   imports  from  DLLs,	and create the necessary thunking symbols when
	   building the	DLLs with those	DATA  exports.	 This  generally  will
	   'just work' -- but sometimes	you may	see this message:

	   "variable  '<var>' can't be auto-imported. Please read the documen-
	   tation for ld's "--enable-auto-import" for details."

	   This	message	occurs when some (sub)expression accesses  an  address
	   ultimately  given  by the sum of two	constants (Win32 import	tables
	   only	allow one).  Instances where this may occur  include  accesses
	   to  member  fields of struct	variables imported from	a DLL, as well
	   as using a constant index into an array variable  imported  from  a
	   DLL.	  Any multiword	variable (arrays, structs, long	long, etc) may
	   trigger this	error condition.  However,  regardless	of  the	 exact
	   data	type of	the offending exported variable, ld will always	detect
	   it, issue the warning, and exit.

	   There are several ways to address this  difficulty,	regardless  of
	   the data type of the	exported variable:

	   One solution	is to force one	of the 'constants' to be a variable --
	   that	is, unknown and	un-optimizable at compile time.	  For  arrays,
	   there  are  two  possibilities:  a)	make  the indexee (the array's
	   address) a variable,	or b) make the 'constant'  index  a  variable.
	   Thus:

		   extern type extern_array[];
		   extern_array[1] -->
		      {	volatile type *t=extern_array; t[1] }

	   or

		   extern type extern_array[];
		   extern_array[1] -->
		      {	volatile int t=1; extern_array[t] }

	   For	structs	 (and most other multiword data	types) the only	option
	   is to make the struct itself	(or the	long long, or the  ...)	 vari-
	   able:

		   extern struct s extern_struct;
		   extern_struct.field -->
		      {	volatile struct	s *t=&extern_struct; t->field }

	   or

		   extern long long extern_ll;
		   extern_ll -->
		     { volatile	long long * local_ll=&extern_ll; *local_ll }

	   A  second  method  of  dealing  with	 this difficulty is to abandon
	   'auto-import'  for  the  offending  symbol	and   mark   it	  with
	   "__declspec(dllimport)".   However, in practice that	requires using
	   compile-time	#defines to indicate whether you are building  a  DLL,
	   building  client  code  that	will link to the DLL, or merely	build-
	   ing/linking to a static library.   In making	the choice between the
	   various methods of resolving	the 'direct address with constant off-
	   set'	problem, you should consider typical real-world	usage:

	   Original:

		   --foo.h
		   extern int arr[];
		   --foo.c
		   #include "foo.h"
		   void	main(int argc, char **argv){
		     printf("%d\n",arr[1]);
		   }

	   Solution 1:

		   --foo.h
		   extern int arr[];
		   --foo.c
		   #include "foo.h"
		   void	main(int argc, char **argv){
		     /*	This workaround	is for win32 and cygwin; do not	"optimize" */
		     volatile int *parr	= arr;
		     printf("%d\n",parr[1]);
		   }

	   Solution 2:

		   --foo.h
		   /* Note: auto-export	is assumed (no __declspec(dllexport)) */
		   #if (defined(_WIN32)	|| defined(__CYGWIN__))	&& \
		     !(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
		   #define FOO_IMPORT __declspec(dllimport)
		   #else
		   #define FOO_IMPORT
		   #endif
		   extern FOO_IMPORT int arr[];
		   --foo.c
		   #include "foo.h"
		   void	main(int argc, char **argv){
		     printf("%d\n",arr[1]);
		   }

	   A third way to avoid	this problem is	to re-code your	library	to use
	   a functional	interface rather than a	data interface for the offend-
	   ing variables (e.g. set_foo() and get_foo() accessor	functions).

       --disable-auto-import
	   Do not  attempt  to	do  sophisticalted  linking  of	 "_symbol"  to
	   "__imp__symbol" for DATA imports from DLLs.

       --enable-extra-pe-debug
	   Show	 additional debug info related to auto-import symbol thunking.

       --section-alignment
	   Sets	the section alignment.	Sections in memory will	 always	 begin
	   at  addresses  which	 are  a	 multiple of this number.  Defaults to
	   0x1000.

       --stack reserve
       --stack reserve,commit
	   Specify the amount of memory	to reserve (and	optionally commit)  to
	   be used as stack for	this program.  The default is 2Mb reserved, 4K
	   committed.

       --subsystem which
       --subsystem which:major
       --subsystem which:major.minor
	   Specifies the subsystem under which your program will execute.  The
	   legal  values  for  which  are  "native", "windows",	"console", and
	   "posix".  You may optionally	set the	subsystem version also.

ENVIRONMENT
       You can change the behavior of ld with the environment variables	 "GNU-
       TARGET",	"LDEMULATION", and "COLLECT_NO_DEMANGLE".

       "GNUTARGET" determines the input-file object format if you don't	use -b
       (or its synonym --format).  Its value should be one of  the  BFD	 names
       for an input format.  If	there is no "GNUTARGET"	in the environment, ld
       uses the	natural	format	of  the	 target.  If  "GNUTARGET"  is  set  to
       "default"  then	BFD attempts to	discover the input format by examining
       binary input files; this	method often succeeds, but there are potential
       ambiguities, since there	is no method of	ensuring that the magic	number
       used to specify object-file formats is unique.  However,	the configura-
       tion  procedure	for  BFD on each system	places the conventional	format
       for that	system first in	the search-list, so ambiguities	 are  resolved
       in favor	of convention.

       "LDEMULATION"  determines the default emulation if you don't use	the -m
       option.	The emulation can affect various aspects of linker  behaviour,
       particularly  the  default  linker  script.  You	can list the available
       emulations with the --verbose or	-V options.  If	the -m option  is  not
       used,  and  the	"LDEMULATION" environment variable is not defined, the
       default emulation depends upon how the linker was configured.

       Normally, the linker will default to demangling symbols.	  However,  if
       "COLLECT_NO_DEMANGLE"  is  set in the environment, then it will default
       to not demangling symbols.  This	environment variable is	used in	a sim-
       ilar  fashion  by the "gcc" linker wrapper program.  The	default	may be
       overridden by the --demangle and	--no-demangle options.

SEE ALSO
       ar(1), nm(1), objcopy(1), objdump(1), readelf(1)	and the	 Info  entries
       for binutils and	ld.

COPYRIGHT
       Copyright  (c)  1991,  92,  93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free
       Software	Foundation, Inc.

       Permission is granted to	copy, distribute and/or	modify	this  document
       under  the  terms of the	GNU Free Documentation License,	Version	1.1 or
       any later version published by the Free Software	 Foundation;  with  no
       Invariant  Sections,  with no Front-Cover Texts,	and with no Back-Cover
       Texts.  A copy of the license is	included in the	section	entitled  "GNU
       Free Documentation License".

binutils-2.13			  2002-10-30				 LD(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | SEE ALSO | COPYRIGHT

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=ld&sektion=1&manpath=FreeBSD+5.2.1-RELEASE>

home | help