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

       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
           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-

       -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.
           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.

           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
           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.
           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

           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.

       -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
           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
           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
           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
           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

           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
           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-
           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

       --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-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.
           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.  [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
           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]

       --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.   [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
           [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
           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;

           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-

       --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",  and
           "posix".  You may optionally set the subsystem version also.  [This
           option is specific to the i386 PE targeted port of the linker]

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
       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-2.15                     2004-05-17                             LD(1)