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NAME

       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" 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 execution 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 standard, 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 descriptions below.

       Non-option arguments are object files or archives which are to be linked together.  They
       may follow, precede, or be mixed in with command-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 specified, 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 augments 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.  Specifying a script in this way merely augments the main linker
       script, with the extra commands placed after the main script; use the -T option to replace
       the default linker script entirely, but note the effect of the "INSERT" command.

       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 preceded 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 immediately 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,--start-group foo.o bar.o -Wl,--end-group

       This is important, because otherwise the compiler driver program may silently drop the
       linker options, resulting in a bad link.  Confusion may also arise when passing options
       that require values through a driver, as the use of a space between option and argument
       acts as a separator, and causes the driver to pass only the option to the linker and the
       argument to the compiler.  In this case, it is simplest to use the joined forms of both
       single- and multiple-letter options, such as:

                 gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.map

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

       @file
           Read command-line options from file.  The options read are inserted in place of the
           original @file option.  If file does not exist, or cannot be read, then the option
           will be treated literally, and not removed.

           Options in file are separated by whitespace.  A whitespace character may be included
           in an option by surrounding the entire option in either single or double quotes.  Any
           character (including a backslash) may be included by prefixing the character to be
           included with a backslash.  The file may itself contain additional @file options; any
           such options will be processed recursively.

       -a keyword
           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.

       -A architecture
       --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 "GNUTARGET".

           You can also define the input format from a script, using the command "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 documentation.  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 symbol 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.

       --exclude-modules-for-implib module,module,...
           Specifies a list of object files or archive members, from which symbols should not be
           automatically exported, but which should be copied wholesale into the import library
           being generated during the link.  The module names may be delimited by commas or
           colons, and must match exactly the filenames used by ld to open the files; for archive
           members, this is simply the member name, but for object files the name listed must
           include and match precisely any path used to specify the input file on the linker's
           command-line.  This option is available only for the i386 PE targeted port of the
           linker.  Symbols explicitly listed in a .def file are still exported, regardless of
           this option.

       -E
       --export-dynamic
       --no-export-dynamic
           When creating a dynamically linked executable, using the -E option or the
           --export-dynamic option causes the linker to 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 either of these options (or use the --no-export-dynamic option to
           restore the default behavior), the dynamic symbol table will normally 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 dynamic list to control what symbols should be added to the
           dynamic symbol table if the output format supports it.  See the description of
           --dynamic-list.

           Note that this option is specific to ELF targeted ports.  PE targets support a similar
           function to export all symbols from a DLL or EXE; see the description of
           --export-all-symbols below.

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

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

       -f name
       --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 auxiliary 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 debugging 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 provided by the object
           name.

           Some older linkers used the -F option throughout a compilation toolchain for
           specifying object-file format for both input and output 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.

       -G value
       --gpsize=value
           Set the maximum size of objects to be optimized using the GP register 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.

       -h name
       -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.

       -l namespec
       --library=namespec
           Add the archive or object file specified by namespec to the list of files to link.
           This option may be used any number of times.  If namespec is of the form :filename, ld
           will search the library path for a file called filename, otherwise it will search the
           library path for a file called libnamespec.a.

           On systems which support shared libraries, ld may also search for files other than
           libnamespec.a.  Specifically, on ELF and SunOS systems, ld will search a directory for
           a library called libnamespec.so before searching for one called libnamespec.a.  (By
           convention, a ".so" extension indicates a shared library.)  Note that this behavior
           does not apply to :filename, which always specifies a file called filename.

           The linker will search an archive only once, at the location where it is specified on
           the command line.  If the archive defines a symbol which was undefined in some object
           which appeared before the archive on the command line, the linker will include the
           appropriate 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.  However, if you are
           using ld on AIX, note that it is different from the behaviour of the AIX linker.

       -L searchdir
       --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
           specified on the command line are searched before the default directories.  All -L
           options apply to all -l options, regardless of the order in which the options appear.
           -L options do not affect how ld searches for a linker script unless -T option is
           specified.

           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.

       -m emulation
           Emulate the emulation linker.  You can list the available emulations 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 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.

           •   The values assigned to symbols.

               Note - symbols whose values are computed by an expression which involves a
               reference to a previous value of the same symbol may not have correct result
               displayed in the link map.  This is because the linker discards intermediate
               results and only retains the final value of an expression.  Under such
               circumstances the linker will display the final value enclosed by square brackets.
               Thus for example a linker script containing:

                          foo = 1
                          foo = foo * 4
                          foo = foo + 8

               will produce the following output in the link map if the -M option is used:

                          0x00000001                foo = 0x1
                          [0x0000000c]                foo = (foo * 0x4)
                          [0x0000000c]                foo = (foo + 0x8)

               See Expressions for more information about expressions in linker scripts.

       -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 probably should only be enabled for the final
           binary.  At the moment this option only affects ELF shared library generation.  Future
           releases of the linker may make more use of this option.  Also currently there is no
           difference in the linker's behaviour for different non-zero values of this option.
           Again this may change with future releases.

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

           This option is currently only supported on ELF platforms.

       --force-dynamic
           Force the output file to have dynamic sections.  This option is specific to VxWorks
           targets.

       -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 followed 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.

       -dT scriptfile
       --default-script=scriptfile
           Use scriptfile as the default linker script.

           This option is similar to the --script option except that processing of the script is
           delayed until after the rest of the command line has been processed.  This allows
           options placed after the --default-script option on the command line to affect the
           behaviour of the linker script, which can be important when the linker command line
           cannot be directly controlled by the user.  (eg because the command line is being
           constructed by another tool, such as gcc).

       -u symbol
       --undefined=symbol
           Force symbol to be entered in the output file as an undefined symbol.  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.  (These symbols start with system-specific local
           label prefixes, typically .L for ELF systems or L for traditional a.out systems.)

       -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.

           execstack
               Marks the object as requiring executable stack.

           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
               runtime 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.

           lazy
               When generating an executable or shared library, mark it to tell the dynamic
               linker to defer function call resolution to the point when the function is called
               (lazy binding), rather than at load time.  Lazy binding is the default.

           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".

           noexecstack
               Marks the object as not requiring executable stack.

           norelro
               Don't create an ELF "PT_GNU_RELRO" segment header in the object.

           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.

           relro
               Create an ELF "PT_GNU_RELRO" segment header in the object.

           max-page-size=value
               Set the emulation maximum page size to value.

           common-page-size=value
               Set the emulation common page size to value.

           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 undefined 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
           symbol referred to by an object in an archive that appears later on the command line,
           the linker would not be able to resolve that reference.  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 mentioned on the command
           line after the --as-needed option.  Normally, the linker will add a DT_NEEDED tag for
           each dynamic library mentioned on the command line, regardless of whether the library
           is actually needed.  --as-needed causes a DT_NEEDED tag to only be emitted for a
           library that satisfies a symbol reference from regular objects which is undefined at
           the point that the library was linked, or, if the library is not found in the
           DT_NEEDED lists of other libraries linked up to that point, a reference from another
           dynamic library.  --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 platforms 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.  This option can be used with
           -shared.  Doing so means that a shared library is being created but that all of the
           library's external references must be resolved by pulling in entries from static
           libraries.

       -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 override the definition within the shared library.  This
           option is only meaningful on ELF platforms which support shared libraries.

       -Bsymbolic-functions
           When creating a shared library, bind references to global function symbols to the
           definition within the shared library, if any.  This option is only meaningful on ELF
           platforms which support shared libraries.

       --dynamic-list=dynamic-list-file
           Specify the name of a dynamic list file to the linker.  This is typically used when
           creating shared libraries to specify a list of global symbols whose references
           shouldn't be bound to the definition within the shared library, or creating
           dynamically linked executables to specify a list of symbols which should be added to
           the symbol table in the executable.  This option is only meaningful on ELF platforms
           which support shared libraries.

           The format of the dynamic list is the same as the version node without scope and node
           name.  See VERSION for more information.

       --dynamic-list-data
           Include all global data symbols to the dynamic list.

       --dynamic-list-cpp-new
           Provide the builtin dynamic list for C++ operator new and delete.  It is mainly useful
           for building shared libstdc++.

       --dynamic-list-cpp-typeinfo
           Provide the builtin dynamic list for C++ runtime type identification.

       --check-sections
       --no-check-sections
           Asks the linker not to check section addresses after they have been assigned to see if
           there are 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.  Section overlap is not usually
           checked for relocatable links.  You can force checking in that case by using the
           --check-sections option.

       --cref
           Output a cross reference table.  If a linker map file is being generated, the cross
           reference table is printed to the map file.  Otherwise, 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 Common 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, consider 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.  Different
           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.

       -Ifile
       --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
       --no-fatal-warnings
           Treat all warnings as errors.  The default behaviour can be restored with the option
           --no-fatal-warnings.

       --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.

       --gc-sections
       --no-gc-sections
           Enable garbage collection of unused input sections.  It is ignored on targets that do
           not support this option.  The default behaviour (of not performing this garbage
           collection) can be restored by specifying --no-gc-sections on the command line.

           --gc-sections decides which input sections are used by examining symbols and
           relocations.  The section containing the entry symbol and all sections containing
           symbols undefined on the command-line will be kept, as will sections containing
           symbols referenced by dynamic objects.  Note that when building shared libraries, the
           linker must assume that any visible symbol is referenced.  Once this initial set of
           sections has been determined, the linker recursively marks as used any section
           referenced by their relocations.  See --entry and --undefined.

           This option can be set when doing a partial link (enabled with option -r).  In this
           case the root of symbols kept must be explicitely specified either by an --entry or
           --undefined option or by a "ENTRY" command in the linker script.

       --print-gc-sections
       --no-print-gc-sections
           List all sections removed by garbage collection.  The listing is printed on stderr.
           This option is only effective if garbage collection has been enabled via the
           --gc-sections) option.  The default behaviour (of not listing the sections that are
           removed) can be restored by specifying --no-print-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 output 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 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 default behaviour is to report errors for any undefined symbols referenced in
           shared libraries if the linker is being used to create an executable, but to allow
           them if the linker is being used to create a shared library.

           The reasons for allowing undefined symbol references in shared libraries specified at
           link time are that:

           •   A shared library specified at link time may not be the same as the one that is
               available at load time, so the symbol might actually be resolvable at load time.

           •   There are some operating systems, eg BeOS and HPPA, where undefined symbols in
               shared libraries are normal.

               The BeOS kernel for example patches shared libraries at load time to select
               whichever function is most appropriate for the current architecture.  This is
               used, for example, to dynamically select an appropriate memset function.

       --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 unversioned exported symbols.

       --default-imported-symver
           Create and use a default symbol version (the soname) for unversioned 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 endiannesses.  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-warn-search-mismatch
           Normally ld will give a warning if it finds an incompatible library during a library
           search.  This option silences the warning.

       --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 encounters 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 supported 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 gradually, to conserve run-time memory.

           --retain-symbols-file does not discard undefined symbols, or symbols 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 file systems.

           For compatibility with other ELF linkers, if the -R option is followed 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 runtime, whereas the -rpath-link option is only effective
               at link time. Searching -rpath in this way is only supported by native linkers and
               cross linkers which have been configured with the --with-sysroot option.

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

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

           5.  For a native linker, the search 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
       --sort-common=ascending
       --sort-common=descending
           This option tells ld to sort the common symbols by alignment in ascending or
           descending order when it places them in the appropriate output sections.  The symbol
           alignments considered are sixteen-byte or larger, eight-byte, four-byte, two-byte, and
           one-byte. This is to prevent gaps between symbols due to alignment constraints.  If no
           sorting order is specified, then descending order is assumed.

       --sort-section=name
           This option will apply "SORT_BY_NAME" to all wildcard section patterns 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 single output section in
           the file contains more than count relocations.  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 relocations 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 redistribution, so if a single input section contains more than count relocations
           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 configure-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.

       -Ttext-segment=org
           When creating an ELF executable or shared object, it will set the address of the first
           byte of the text segment.

       --unresolved-symbols=method
           Determine how to handle unresolved symbols.  There are four possible 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 controlled 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 typically used when
           creating shared libraries to specify additional information about the version
           hierarchy for the library being created.  This option is only fully supported on ELF
           platforms which support shared libraries; see VERSION.  It is partially supported on
           PE platforms, which can use version scripts to filter symbol visibility in auto-export
           mode: any symbols marked local in the version script will not be exported.

       --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 symbols 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 different sizes, it picks the largest size.  The linker turns a common 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 definition 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 symbol.

                       <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 multiple global pointer values in order to be able to address all possible
           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 module 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 section.  The address will only be changed if it
           not explicitly specified; 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-alternate-em
           Warn if an object has alternate ELF machine code.

       --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 symbol 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".

       --eh-frame-hdr
           Request creation of ".eh_frame_hdr" section and ELF "PT_GNU_EH_FRAME" segment header.

       --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 created.
           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.

       --hash-style=style
           Set the type of linker's hash table(s).  style can be either "sysv" for classic ELF
           ".hash" section, "gnu" for new style GNU ".gnu.hash" section or "both" for both the
           classic ELF ".hash" and new style GNU ".gnu.hash" hash tables.  The default is "sysv".

       --reduce-memory-overheads
           This option reduces memory requirements at ld runtime, at the expense of linking
           speed.  This was introduced 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 effect 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.

       --build-id
       --build-id=style
           Request creation of ".note.gnu.build-id" ELF note section.  The contents of the note
           are unique bits identifying this linked file.  style can be "uuid" to use 128 random
           bits, "sha1" to use a 160-bit SHA1 hash on the normative parts of the output contents,
           "md5" to use a 128-bit MD5 hash on the normative parts of the output contents, or
           "0xhexstring" to use a chosen bit string specified as an even number of hexadecimal
           digits ("-" and ":" characters between digit pairs are ignored).  If style is omitted,
           "sha1" is used.

           The "md5" and "sha1" styles produces an identifier that is always the same in an
           identical output file, but will be unique among all nonidentical output files.  It is
           not intended to be compared as a checksum for the file's contents.  A linked file may
           be changed later by other tools, but the build ID bit string identifying the original
           linked file does not change.

           Passing "none" for style disables the setting from any "--build-id" options earlier on
           the command line.

       The i386 PE linker supports the -shared option, which causes the output to be a
       dynamically linked library (DLL) instead of a normal executable.  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-long-section-names
       --disable-long-section-names
           The PE variants of the Coff object format add an extension that permits the use of
           section names longer than eight characters, the normal limit for Coff.  By default,
           these names are only allowed in object files, as fully-linked executable images do not
           carry the Coff string table required to support the longer names.  As a GNU extension,
           it is possible to allow their use in executable images as well, or to (probably
           pointlessly!)  disallow it in object files, by using these two options.  Executable
           images generated with these long section names are slightly non-standard, carrying as
           they do a string table, and may generate confusing output when examined with non-GNU
           PE-aware tools, such as file viewers and dumpers.  However, GDB relies on the use of
           PE long section names to find Dwarf-2 debug information sections in an executable
           image at runtime, and so if neither option is specified on the command-line, ld will
           enable long section names, overriding the default and technically correct behaviour,
           when it finds the presence of debug information while linking an executable image and
           not stripping symbols.  [This option is valid for all PE targeted ports 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 --disable-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 function attributes, the default is to not export anything else unless this option
           is given.  Note that the symbols "DllMain@12", "DllEntryPoint@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-private 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_noncygwin_dll_entry@12", "_fmode", "_impure_ptr",
           "cygwin_attach_dll", "cygwin_premain0", "cygwin_premain1", "cygwin_premain2",
           "cygwin_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 number of bytes 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 overlap any other dlls.  The default is 0x400000 for executables, and
           0x10000000 for dlls.  [This option is specific to the i386 PE targeted 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 "Characteristics" field of the COFF header is set
           to indicate that this executable supports virtual addresses greater than 2 gigabytes.
           This should be used in conjunction 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
           automatically 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 specified using the
           "--image-base" argument.  By using a hash generated from the dllname to create unique
           image bases for each DLL, in-memory 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.

           Note - use of the 'auto-import' extension will also cause read only data which would
           normally be placed into the .rdata section to be placed into the .data section
           instead.  This is in order to work around a problem with consts that is described
           here: http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html

           Using 'auto-import' generally will 'just work' -- but sometimes you may see this
           message:

           "variable '<var>' can't be auto-imported. Please read the documentation 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 variable -- that is,
           unknown and un-optimizable at compile time.  For arrays, there are two possibilities:
           a) make the indexee (the array's address) a variable, or b) make the 'constant' index
           a variable.  Thus:

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

           or

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

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

                   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 building/linking to a static
           library.   In making the choice between the various methods of resolving the 'direct
           address with constant offset' 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 functions).  [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 specific 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 number of bytes 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 specific to the i386 PE targeted port of the linker]

           The following options set flags in the "DllCharacteristics" field of the PE file
           header: [These options are specific to PE targeted ports of the linker]

       --dynamicbase
           The image base address may be relocated using address space layout randomization
           (ASLR).  This feature was introduced with MS Windows Vista for i386 PE targets.

       --forceinteg
           Code integrity checks are enforced.

       --nxcompat
           The image is compatible with the Data Execution Prevention.  This feature was
           introduced with MS Windows XP SP2 for i386 PE targets.

       --no-isolation
           Although the image understands isolation, do not isolate the image.

       --no-seh
           The image does not use SEH. No SE handler may be called from this image.

       --no-bind
           Do not bind this image.

       --wdmdriver
           The driver uses the MS Windows Driver Model.

       --tsaware
           The image is Terminal Server aware.

       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.

       The following options are supported to control handling of GOT generation when linking for
       68K targets.

       --got=type
           This option tells the linker which GOT generation scheme to use.  type should be one
           of single, negative, multigot or target.  For more information refer to the Info entry
           for ld.

ENVIRONMENT

       You can change the behaviour of ld with the environment variables "GNUTARGET",
       "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 configuration 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 similar fashion by the "gcc" linker
       wrapper program.  The default may be overridden by the --demangle and --no-demangle
       options.

SEE ALSO

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

COPYRIGHT

       Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, 2003, 2004, 2005,
       2006, 2007, 2008, 2009 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 1.3 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".