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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
            archive  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
            behaviour 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
            archives,  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.
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’’.
 

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