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  cannot 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
       (e.g.  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).

       --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.  This option is
           available only for the i386 PE targeted port of the linker and  for
           ELF  targeted  ports.   For i386 PE, symbols explicitly listed in a
           .def file are still exported, regardless of this option.   For  ELF
           targeted  ports, symbols affected by this option will be treated as
           hidden.

       -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.

           If searchdir begins with "=", then the "=" will be replaced by  the
           sysroot prefix, a path specified when the linker is configured.

           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:

           *   Where object files and symbols are mapped into memory.

           *   How common symbols are allocated.

           *   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, and disable linking against
           shared libraries.  If the output format supports Unix  style  magic
           numbers,  mark  the  output  as "OMAGIC". Note: Although a writable
           text section is allowed for PE-COFF targets, it does not conform to
           the format specification published by Microsoft.

       --no-omagic
           This  option negates most of the effects of the -N option.  It sets
           the text section to be read-only, and forces the data segment to be
           page-aligned.   Note  - this option does not enable linking against
           shared libraries.  Use -Bdynamic for this.

       -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
       --relocatable
           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:

           combreloc
               Combines multiple reloc sections and sorts them to make dynamic
               symbol lookup caching possible.

           defs
               Disallows undefined symbols in object files.  Undefined symbols
               in shared libraries are still allowed.

           initfirst
               This option is only meaningful when building a  shared  object.
               It  marks  the  object  so that its runtime initialization will
               occur before the runtime initialization of  any  other  objects
               brought  into the process at the same time.  Similarly the run-
               time finalization of the object will occur  after  the  runtime
               finalization of 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 filters be processed immediately  at
               runtime.

           muldefs
               Allows multiple definitions.

           nocombreloc
               Disables multiple reloc sections combining.

           nocopyreloc
               Disables production of copy relocs.

           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 When generating an executable or shared  library,  mark  it  to
               tell the dynamic linker to resolve all symbols when the program
               is started, or when the  shared  library  is  linked  to  using
               dlopen,  instead  of  deferring function call resolution to the
               point when the function is first called.

           origin
               Marks the object may contain $ORIGIN.

           Other keywords are ignored for Solaris compatibility.

       -( 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.

       --accept-unknown-input-arch
       --no-accept-unknown-input-arch
           Tells the linker to accept input files whose architecture cannot be
           recognised.   The  assumption  is that the user knows what they are
           doing and deliberately wants to link in these unknown input  files.
           This  was the default behaviour of the linker, before release 2.14.
           The default behaviour from release 2.14 onwards is to  reject  such
           input files, and so the --accept-unknown-input-arch option has been
           added to restore the old behaviour.

       --as-needed
       --no-as-needed
           This option affects ELF DT_NEEDED tags for dynamic  libraries  men-
           tioned on the command line after the --as-needed option.  Normally,
           the linker will add a DT_NEEDED tag for each dynamic  library  men-
           tioned  on  the  command line, regardless of whether the library is
           actually needed.  --as-needed causes  DT_NEEDED  tags  to  only  be
           emitted for libraries that satisfy some symbol reference from regu-
           lar objects which is undefined at the point that  the  library  was
           linked.  --no-as-needed restores the default behaviour.

       --add-needed
       --no-add-needed
           This  option  affects  the  treatment of dynamic libraries from ELF
           DT_NEEDED tags in dynamic libraries mentioned on the  command  line
           after  the --no-add-needed option.  Normally, the linker will add a
           DT_NEEDED  tag  for  each  dynamic  library  from  DT_NEEDED  tags.
           --no-add-needed  causes  DT_NEEDED  tags  will never be emitted for
           those libraries from  DT_NEEDED  tags.  --add-needed  restores  the
           default behaviour.

       -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.
           --unresolved-symbols=report-all  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.   This
           option also implies --unresolved-symbols=report-all.

       -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.

       --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. 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
           Report  unresolved  symbol  references  from  regular object files.
           This is done even if the linker is creating a  non-symbolic  shared
           library.   The switch --[no-]allow-shlib-undefined controls the be-
           haviour  for  reporting  unresolved  references  found  in   shared
           libraries being linked in.

       --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
       --no-allow-shlib-undefined
           Allows  (the  default)  or  disallows  undefined  symbols in shared
           libraries.  This switch is similar to --no-undefined except that it
           determines the behaviour when the undefined symbols are in a shared
           library rather than a regular object file.  It does not affect  how
           undefined symbols in regular object files are handled.

           The  reason that --allow-shlib-undefined is the default is that the
           shared library being specified at link time may not be the same  as
           the  one that is available at load time, so the symbols might actu-
           ally be resolvable at load time.  Plus there are some systems,  (eg
           BeOS)  where undefined symbols in shared libraries is normal.  (The
           kernel patches them at load time to select which function  is  most
           appropriate for the current architecture.  This is used for example
           to dynamically select an appropriate memset function).   Apparently
           it  is also normal for HPPA shared libraries to have undefined sym-
           bols.

       --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.

       --default-symver
           Create and use a default symbol version  (the  soname)  for  unver-
           sioned exported symbols.

       --default-imported-symver
           Create  and  use  a  default symbol version (the soname) for unver-
           sioned imported symbols.

       --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.

       -pie
       --pic-executable
           Create  a  position independent executable.  This is currently only
           supported on ELF platforms.  Position independent  executables  are
           similar  to  shared  libraries  in  that  they are relocated by the
           dynamic linker to the virtual  address  the  OS  chooses  for  them
           (which  can  vary  between  invocations).   Like normal dynamically
           linked executables they can be executed and symbols defined in  the
           executable cannot be overridden by shared libraries.

       -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.

       --sort-section name
           This option will apply "SORT_BY_NAME" to all wildcard section  pat-
           terns in the linker script.

       --sort-section alignment
           This  option will apply "SORT_BY_ALIGNMENT" to all wildcard section
           patterns in the linker script.

       --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.

       --sysroot=directory
           Use  directory  as the location of the sysroot, overriding the con-
           figure-time default.  This option is only supported by linkers that
           were configured using --with-sysroot.

       --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
           Same as --section-start, with ".bss", ".data"  or  ".text"  as  the
           sectionname.

       --unresolved-symbols=method
           Determine  how to handle unresolved symbols.  There are four possi-
           ble values for method:

           ignore-all
               Do not report any unresolved symbols.

           report-all
               Report all unresolved symbols.  This is the default.

           ignore-in-object-files
               Report  unresolved  symbols  that  are  contained   in   shared
               libraries,  but  ignore  them  if they come from regular object
               files.

           ignore-in-shared-libs
               Report unresolved symbols that come from regular object  files,
               but  ignore  them if they come from shared libraries.  This can
               be useful when creating a dynamic binary and it is  known  that
               all  the  shared  libraries  that  it should be referencing are
               included on the linker's command line.

           The behaviour for shared libraries on their own can  also  be  con-
           trolled by the --[no-]allow-shlib-undefined option.

           Normally  the  linker  will  generate  an  error  message  for each
           reported unresolved symbol but the option --warn-unresolved-symbols
           can change this to a warning.

       --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 hierarchy 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
           practise, 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 practise, 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.

       --warn-shared-textrel
           Warn if the linker adds a DT_TEXTREL to a shared object.

       --warn-unresolved-symbols
           If the linker is going to report  an  unresolved  symbol  (see  the
           option  --unresolved-symbols)  it  will normally generate an error.
           This option makes it generate a warning instead.

       --error-unresolved-symbols
           This restores the linker's default behaviour of  generating  errors
           when it is reporting unresolved symbols.

       --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 (size_t c)
                   {
                     printf ("malloc called with %zu\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.

       --hash-size=number
           Set the default size of the linker's hash tables to a prime  number
           close  to  number.   Increasing this value can reduce the length of
           time it takes the linker to perform its tasks, at  the  expense  of
           increasing  the  linker's  memory requirements.  Similarly reducing
           this value can reduce the memory requirements  at  the  expense  of
           speed.

       --reduce-memory-overheads
           This  option  reduces  memory  requirements  at  ld runtime, at the
           expense of linking speed.  This was introduced to to select the old
           O(n^2)  algorithm for link map file generation, rather than the new
           O(n) algorithm which uses about 40% more memory for symbol storage.

           Another  affect of the switch is to set the default hash table size
           to 1021, which again saves memory at the cost  of  lengthening  the
           linker's  run  time.   This  is not done however if the --hash-size
           switch has been used.

           The --reduce-memory-overheads switch may be also be used to  enable
           other tradeoffs in future versions of the linker.

       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.  [This option is specific to
           the i386 PE targeted port of the linker]

       --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.
           [This is an i386 PE specific option]

       --dll
           Create a DLL instead of a regular executable.   You  may  also  use
           -shared  or  specify  a  "LIBRARY"  in  a given ".def" file.  [This
           option is specific to the i386 PE targeted port of the linker]

       --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.  [This option is specific to the  i386
           PE targeted port of the linker]

       --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".  [This option is specific to the i386
           PE targeted port of the linker]

       --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.
           [This  option  is  specific  to  the  i386  PE targeted port of the
           linker]

       --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.  [This option is specific to the i386 PE targeted  port  of
           the linker]

       --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.   [This  option is specific to the i386 PE targeted port
           of the linker]

       --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.  [This option is specific to the i386 PE tar-
           geted port of the linker]

       --kill-at
           If given, the stdcall suffixes (@nn) will be stripped from  symbols
           before  they are exported.  [This option is specific to the i386 PE
           targeted port of the linker]

       --large-address-aware
           If given, the appropriate bit in the  ``Charateristics''  field  of
           the  COFF  header  is set to indicate that this executable supports
           virtual addresses greater than 2 gigabytes.  This should be used in
           conjuction  with  the /3GB or /USERVA=value megabytes switch in the
           ``[operating systems]'' section of the BOOT.INI.   Otherwise,  this
           bit  has  no effect.  [This option is specific to PE targeted ports
           of the linker]

       --major-image-version value
           Sets the major number of the ``image  version''.   Defaults  to  1.
           [This  option  is  specific  to  the  i386  PE targeted port of the
           linker]

       --major-os-version value
           Sets the major number of the ``os version''.  Defaults to 4.  [This
           option is specific to the i386 PE targeted port of the linker]

       --major-subsystem-version value
           Sets the major number of the ``subsystem version''.  Defaults to 4.
           [This option is specific to  the  i386  PE  targeted  port  of  the
           linker]

       --minor-image-version value
           Sets  the  minor  number  of the ``image version''.  Defaults to 0.
           [This option is specific to  the  i386  PE  targeted  port  of  the
           linker]

       --minor-os-version value
           Sets the minor number of the ``os version''.  Defaults to 0.  [This
           option is specific to the i386 PE targeted port of the linker]

       --minor-subsystem-version value
           Sets the minor number of the ``subsystem version''.  Defaults to 0.
           [This  option  is  specific  to  the  i386  PE targeted port of the
           linker]

       --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.  [This option is specific  to
           the i386 PE targeted port of the linker]

       --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 behaviour makes it possible
           to  skip  a separate "dlltool" import library creation step.  [This
           option is specific to the i386 PE targeted port of the linker]

       --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.  [This option is specific to the i386 PE targeted port
           of the linker]

       --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.   [This option is specific to the i386 PE targeted port of
           the linker]

       --dll-search-prefix string
           When linking dynamically to a dll without an import library, search
           for  "<string><basename>.dll" in preference to "lib<basename>.dll".
           This behaviour allows easy distinction between DLLs built  for  the
           various   "subplatforms":  native,  cygwin,  uwin,  pw,  etc.   For
           instance,  cygwin  DLLs  typically  use  "--dll-search-prefix=cyg".
           [This  option  is  specific  to  the  i386  PE targeted port of the
           linker]

       --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 import libraries with those DATA exports. Note: Use of
           the  'auto-import'  extension  will  cause  the text section of the
           image file to be made writable. This does not conform  to  the  PE-
           COFF format specification published by Microsoft.

           Using 'auto-import' 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 way is to use --enable-runtime-pseudo-reloc switch. This leaves
           the  task  of  adjusting references in your client code for runtime
           environment, so this method works  only  when  runtime  environment
           supports this feature.

           A  second solution is to force one of the 'constants' to be a vari-
           able -- 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  third  method  of  dealing  with  this  difficulty is to abandon
           'auto-import'  for  the  offending  symbol   and   mark   it   with
           "__declspec(dllimport)".   However, in practise 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 fourth way to avoid this problem is to re-code  your  library  to
           use  a  functional  interface  rather than a data interface for the
           offending variables (e.g. set_foo() and  get_foo()  accessor  func-
           tions).   [This  option is specific to the i386 PE targeted port of
           the linker]

       --disable-auto-import
           Do  not  attempt  to  do  sophisticated  linking  of  "_symbol"  to
           "__imp__symbol"  for  DATA imports from DLLs.  [This option is spe-
           cific to the i386 PE targeted port of the linker]

       --enable-runtime-pseudo-reloc
           If your code contains expressions described in --enable-auto-import
           section,  that is, DATA imports from DLL with non-zero offset, this
           switch will create a vector of 'runtime pseudo  relocations'  which
           can  be  used  by  runtime environment to adjust references to such
           data in your client code.  [This option is specific to the i386  PE
           targeted port of the linker]

       --disable-runtime-pseudo-reloc
           Do  not  create pseudo relocations for non-zero offset DATA imports
           from DLLs.  This is the default.  [This option is specific  to  the
           i386 PE targeted port of the linker]

       --enable-extra-pe-debug
           Show  additional debug info related to auto-import symbol thunking.
           [This option is specific to  the  i386  PE  targeted  port  of  the
           linker]

       --section-alignment
           Sets  the  section alignment.  Sections in memory will always begin
           at addresses which are a multiple  of  this  number.   Defaults  to
           0x1000.   [This  option is specific to the i386 PE targeted port of
           the linker]

       --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.  [This option is specific to the i386 PE  targeted  port
           of the linker]

       --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", "posix",
           and  "xbox".   You  may  optionally set the subsystem version also.
           Numeric values are also accepted for which.  [This option  is  spe-
           cific to the i386 PE targeted port of the linker]

       The  68HC11  and 68HC12 linkers support specific options to control the
       memory bank switching mapping and trampoline code generation.

       --no-trampoline
           This option disables the generation of  trampoline.  By  default  a
           trampoline is generated for each far function which is called using
           a "jsr" instruction (this happens when a pointer to a far  function
           is taken).

       --bank-window name
           This  option  indicates to the linker the name of the memory region
           in the MEMORY specification that describes the memory bank  window.
           The definition of such region is then used by the linker to compute
           paging and addresses within the memory window.

ENVIRONMENT
       You can change the behaviour 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, 2002,
       2003, 2004 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-2.16.1                   2005-06-12                             LD(1)

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