ld

LD(7)                   Miscellaneous Information Manual                 LD(7)

NAME
     ld — The GNU Linker

LD
     This file documents the GNU linker ld version "2.17.50 [FreeBSD]
     2007-07-03".

     This document is distributed under the terms of the GNU Free
     Documentation License. A copy of the license is included in the section
     entitled “GNU Free Documentation License”.

Overview
     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 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.See
     Section “BFD”, for more information.

     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).

Invocation
     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.

   Command Line 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 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. Note that specifying a script in this way
     merely augments the main linker script; use the -T option to replace the
     default linker script entirely.See Section “Scripts”.

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

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

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

     @ 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.See Section “i960”, for details.

             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.)  See Section.Dq BFD .

             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.  See Section.Dq Environment .  You can also define the
             input format from a script, using the command TARGET; see Format
             Commands.

     -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 MRI,,MRI Compatible Script Files. 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.See Section “Miscellaneous Commands”.

     -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).See Section “Entry Point”, for a
             discussion of defaults and other ways of specifying the entry
             point.

     --exclude-libs lib, lib,...
             Specifies a list of archive libraries from which symbols should
             not be automatically exported. The library names may be delimited
             by commas or colons. Specifying --exclude-libs ALL excludes
             symbols in all archive libraries from automatic export. This
             option is available only for the i386 PE targeted port of the
             linker and for ELF targeted ports. For i386 PE, symbols
             explicitly listed in a .def file are still exported, regardless
             of this option. For ELF targeted ports, symbols affected by this
             option will be treated as hidden.

     -E

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

             If you do not use this option, the dynamic symbol table will
             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.

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

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

     -f

     --auxiliary name
             When creating an ELF shared object, set the internal DT_AUXILIARY
             field to the specified name. This tells the dynamic linker that
             the symbol table of the shared object should be used as an
             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, otherise it will search
             the library path for a file called lib namespec.a.

             On systems which support shared libraries, ld may also search for
             files other than lib namespec.a.  Specifically, on ELF and SunOS
             systems, ld will search a directory for a library called lib
             namespec.so before searching for one called lib namespec.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.

             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.See Section “Environment”.

             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.

     -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.See
             Section “Scripts”.  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.See Section
             “Scripts”.

             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 DT_NEEDED tags
             to only be emitted for libraries that satisfy some symbol
             reference from regular objects which is undefined at the point
             that the library was linked.  [--no-as-needed] restores the
             default behaviour.

     --add-needed

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

     -assert keyword
             This option is ignored for SunOS compatibility.

     -Bdynamic

     -dy

     -call_shared
             Link against dynamic libraries. This is only meaningful on
             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].

     --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.See Section “Miscellaneous Commands”.

             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 (see Section “Assignments”).  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.

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

     --fatal-warnings
             Treat all warnings as errors.

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

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

     --gc-sections

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

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

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

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

     --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.See Section
             “BFD”.

     -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.See Section “H8/300”.  See Section.Dq
             i960 .  See Section.Dq Xtensa .  See Section.Dq M68HC11/68HC12 .
             See Section.Dq PowerPC ELF32 .

             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, if the [-rpath] and rpath-link options
                  were not used, search the contents of the environment
                  variable LD_RUN_PATH.  It is for the native linker only.

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

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

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

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

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

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

     -shared

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

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

     --sort-section name
             This option will apply SORT_BY_NAME to all wildcard section
             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.

     --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 meaningful on ELF
             platforms which support shared libraries.See Section “VERSION”.

     --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 (see Section “SECTIONS”).

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

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

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

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

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

     --wrap symbol
             Use a wrapper function for symbol.  Any undefined reference to
             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.

     Options Specific to i386 PE Targets

     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-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 amount of memory to reserve (and optionally commit)
             to be used as heap for this program. The default is 1Mb reserved,
             4K committed. [This option is specific to the i386 PE targeted
             port of the linker]

     --image-base value
             Use value as the base address of your program or dll. This is the
             lowest memory location that will be used when your program or dll
             is loaded. To reduce the need to relocate and improve performance
             of your dlls, each should have a unique base address and not
             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.

             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 amount of memory to reserve (and optionally commit)
             to be used as stack for this program. The default is 2Mb
             reserved, 4K committed. [This option is specific to the i386 PE
             targeted port of the linker]

     --subsystem which

     --subsystem which: major

     --subsystem which: major. minor
             Specifies the subsystem under which your program will execute.
             The legal values for which are native, windows, console, posix,
             and xbox.  You may optionally set the subsystem version also.
             Numeric values are also accepted for which.  [This option is
             specific to the i386 PE targeted port of the linker]

     Options specific to Motorola 68HC11 and 68HC12 targets

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

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

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

   Environment Variables
     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 (see Section “BFD”).  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.

Linker Scripts
     Every link is controlled by a linker script.  This script is written in
     the linker command language.

     The main purpose of the linker script is to describe how the sections in
     the input files should be mapped into the output file, and to control the
     memory layout of the output file. Most linker scripts do nothing more
     than this.  However, when necessary, the linker script can also direct
     the linker to perform many other operations, using the commands described
     below.

     The linker always uses a linker script. If you do not supply one
     yourself, the linker will use a default script that is compiled into the
     linker executable.  You can use the --verbose command line option to
     display the default linker script. Certain command line options, such as
     -r or -N, will affect the default linker script.

     You may supply your own linker script by using the -T command line
     option. When you do this, your linker script will replace the default
     linker script.

     You may also use linker scripts implicitly by naming them as input files
     to the linker, as though they were files to be linked.See Section
     “Implicit Linker Scripts”.

   Basic Linker Script Concepts
     We need to define some basic concepts and vocabulary in order to describe
     the linker script language.

     The linker combines input files into a single output file. The output
     file and each input file are in a special data format known as an object
     file format.  Each file is called an object file.  The output file is
     often called an executable, but for our purposes we will also call it an
     object file. Each object file has, among other things, a list of
     sections.  We sometimes refer to a section in an input file as an input
     section; similarly, a section in the output file is an output section.

     Each section in an object file has a name and a size. Most sections also
     have an associated block of data, known as the section contents.  A
     section may be marked as loadable, which mean that the contents should be
     loaded into memory when the output file is run. A section with no
     contents may be allocatable, which means that an area in memory should be
     set aside, but nothing in particular should be loaded there (in some
     cases this memory must be zeroed out). A section which is neither
     loadable nor allocatable typically contains some sort of debugging
     information.

     Every loadable or allocatable output section has two addresses. The first
     is the VMA, or virtual memory address. This is the address the section
     will have when the output file is run. The second is the LMA, or load
     memory address. This is the address at which the section will be loaded.
     In most cases the two addresses will be the same. An example of when they
     might be different is when a data section is loaded into ROM, and then
     copied into RAM when the program starts up (this technique is often used
     to initialize global variables in a ROM based system). In this case the
     ROM address would be the LMA, and the RAM address would be the VMA.

     You can see the sections in an object file by using the objdump program
     with the -h option.

     Every object file also has a list of symbols, known as the symbol table.
     A symbol may be defined or undefined. Each symbol has a name, and each
     defined symbol has an address, among other information. If you compile a
     C or C++ program into an object file, you will get a defined symbol for
     every defined function and global or static variable. Every undefined
     function or global variable which is referenced in the input file will
     become an undefined symbol.

     You can see the symbols in an object file by using the nm program, or by
     using the objdump program with the -t option.

   Linker Script Format
     Linker scripts are text files.

     You write a linker script as a series of commands. Each command is either
     a keyword, possibly followed by arguments, or an assignment to a symbol.
     You may separate commands using semicolons. Whitespace is generally
     ignored.

     Strings such as file or format names can normally be entered directly. If
     the file name contains a character such as a comma which would otherwise
     serve to separate file names, you may put the file name in double quotes.
     There is no way to use a double quote character in a file name.

     You may include comments in linker scripts just as in C, delimited by /*
     and */.  As in C, comments are syntactically equivalent to whitespace.

   Simple Linker Script Example
     Many linker scripts are fairly simple.

     The simplest possible linker script has just one command: SECTIONS.  You
     use the SECTIONS command to describe the memory layout of the output
     file.

     The SECTIONS command is a powerful command. Here we will describe a
     simple use of it. Let's assume your program consists only of code,
     initialized data, and uninitialized data. These will be in the .text,
     .data, and .bss sections, respectively. Let's assume further that these
     are the only sections which appear in your input files.

     For this example, let's say that the code should be loaded at address
     0x10000, and that the data should start at address 0x8000000. Here is a
     linker script which will do that:

           SECTIONS
           {
             . = 0x10000;
             .text : { *(.text) }
             . = 0x8000000;
             .data : { *(.data) }
             .bss : { *(.bss) }
           }

     You write the SECTIONS command as the keyword SECTIONS, followed by a
     series of symbol assignments and output section descriptions enclosed in
     curly braces.

     The first line inside the SECTIONS command of the above example sets the
     value of the special symbol ., which is the location counter. If you do
     not specify the address of an output section in some other way (other
     ways are described later), the address is set from the current value of
     the location counter. The location counter is then incremented by the
     size of the output section. At the start of the SECTIONS command, the
     location counter has the value 0.

     The second line defines an output section, .text.  The colon is required
     syntax which may be ignored for now. Within the curly braces after the
     output section name, you list the names of the input sections which
     should be placed into this output section. The * is a wildcard which
     matches any file name. The expression *(.text) means all .text input
     sections in all input files.

     Since the location counter is 0x10000 when the output section .text is
     defined, the linker will set the address of the .text section in the
     output file to be 0x10000.

     The remaining lines define the .data and .bss sections in the output
     file. The linker will place the .data output section at address
     0x8000000.  After the linker places the .data output section, the value
     of the location counter will be 0x8000000 plus the size of the .data
     output section. The effect is that the linker will place the .bss output
     section immediately after the .data output section in memory.

     The linker will ensure that each output section has the required
     alignment, by increasing the location counter if necessary. In this
     example, the specified addresses for the .text and .data sections will
     probably satisfy any alignment constraints, but the linker may have to
     create a small gap between the .data and .bss sections.

     That's it! That's a simple and complete linker script.

   Simple Linker Script Commands
     In this section we describe the simple linker script commands.

     Setting the Entry Point

     The first instruction to execute in a program is called the entry point.
     You can use the ENTRY linker script command to set the entry point. The
     argument is a symbol name:

           ENTRY(symbol)

     There are several ways to set the entry point. The linker will set the
     entry point by trying each of the following methods in order, and
     stopping when one of them succeeds:

     ·   the -e entry command-line option;

     ·   the ENTRY( symbol) command in a linker script;

     ·   the value of the symbol start, if defined;

     ·   the address of the first byte of the .text section, if present;

     ·   The address 0.

     Commands Dealing with Files

     Several linker script commands deal with files.

     INCLUDE filename
             Include the linker script filename at this point. The file will
             be searched for in the current directory, and in any directory
             specified with the [-L] option. You can nest calls to INCLUDE up
             to 10 levels deep.

     INPUT( file, file, ...)

     INPUT( file file ...)
             The INPUT command directs the linker to include the named files
             in the link, as though they were named on the command line.

             For example, if you always want to include subr.o any time you do
             a link, but you can't be bothered to put it on every link command
             line, then you can put INPUT (subr.o) in your linker script.

             In fact, if you like, you can list all of your input files in the
             linker script, and then invoke the linker with nothing but a -T
             option.

             In case a sysroot prefix is configured, and the filename starts
             with the / character, and the script being processed was located
             inside the sysroot prefix, the filename will be looked for in the
             sysroot prefix.  Otherwise, the linker will try to open the file
             in the current directory.  If it is not found, the linker will
             search through the archive library search path. See the
             description of -L in Options,,Command Line Options.

             If you use INPUT (-l file), ld will transform the name to lib
             file.a, as with the command line argument -l.

             When you use the INPUT command in an implicit linker script, the
             files will be included in the link at the point at which the
             linker script file is included. This can affect archive
             searching.

     GROUP( file, file, ...)

     GROUP( file file ...)
             The GROUP command is like INPUT, except that the named files
             should all be archives, and they are searched repeatedly until no
             new undefined references are created. See the description of -(
             in Options,,Command Line Options.

     AS_NEEDED( file, file, ...)

     AS_NEEDED( file file ...)
             This construct can appear only inside of the INPUT or GROUP
             commands, among other filenames. The files listed will be handled
             as if they appear directly in the INPUT or GROUP commands, with
             the exception of ELF shared libraries, that will be added only
             when they are actually needed. This construct essentially enables
             [--as-needed] option for all the files listed inside of it and
             restores previous [--as-needed] resp.  [--no-as-needed] setting
             afterwards.

     OUTPUT( filename)
             The OUTPUT command names the output file. Using OUTPUT( filename)
             in the linker script is exactly like using -o filename on the
             command line (see Section “Options”).  If both are used, the
             command line option takes precedence.

             You can use the OUTPUT command to define a default name for the
             output file other than the usual default of a.out.

     SEARCH_DIR( path)
             The SEARCH_DIR command adds path to the list of paths where ld
             looks for archive libraries. Using SEARCH_DIR( path) is exactly
             like using -L path on the command line (see Section “Options”).
             If both are used, then the linker will search both paths. Paths
             specified using the command line option are searched first.

     STARTUP( filename)
             The STARTUP command is just like the INPUT command, except that
             filename will become the first input file to be linked, as though
             it were specified first on the command line. This may be useful
             when using a system in which the entry point is always the start
             of the first file.

     Commands Dealing with Object File Formats

     A couple of linker script commands deal with object file formats.

     OUTPUT_FORMAT( bfdname)

     OUTPUT_FORMAT( default, big, little)
             The OUTPUT_FORMAT command names the BFD format to use for the
             output file (see Section “BFD”).  Using OUTPUT_FORMAT( bfdname)
             is exactly like using --oformat bfdname on the command line (see
             Section “Options”).  If both are used, the command line option
             takes precedence.

             You can use OUTPUT_FORMAT with three arguments to use different
             formats based on the -EB and -EL command line options. This
             permits the linker script to set the output format based on the
             desired endianness.

             If neither -EB nor -EL are used, then the output format will be
             the first argument, default.  If -EB is used, the output format
             will be the second argument, big.  If -EL is used, the output
             format will be the third argument, little.

             For example, the default linker script for the MIPS ELF target
             uses this command:

                   OUTPUT_FORMAT(elf32-bigmips, elf32-bigmips, elf32-littlemips)
             This says that the default format for the output file is
             elf32-bigmips, but if the user uses the -EL command line option,
             the output file will be created in the elf32-littlemips format.

     TARGET( bfdname)
             The TARGET command names the BFD format to use when reading input
             files. It affects subsequent INPUT and GROUP commands. This
             command is like using -b bfdname on the command line (see Section
             “Options”).  If the TARGET command is used but OUTPUT_FORMAT is
             not, then the last TARGET command is also used to set the format
             for the output file.See Section “BFD”.

     Other Linker Script Commands

     There are a few other linker scripts commands.

     ASSERT( exp, message)
             Ensure that exp is non-zero. If it is zero, then exit the linker
             with an error code, and print message.

     EXTERN( symbol 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. You may list several
             symbol s for each EXTERN, and you may use EXTERN multiple times.
             This command has the same effect as the -u command-line option.

     FORCE_COMMON_ALLOCATION
             This command has the same effect as the -d command-line option:
             to make ld assign space to common symbols even if a relocatable
             output file is specified ( -r).

     INHIBIT_COMMON_ALLOCATION
             This command has the same effect as the --no-define-common
             command-line option: to make ld omit the assignment of addresses
             to common symbols even for a non-relocatable output file.

     NOCROSSREFS( section section ...)
             This command may be used to tell ld to issue an error about any
             references among certain output sections.

             In certain types of programs, particularly on embedded systems
             when using overlays, when one section is loaded into memory,
             another section will not be. Any direct references between the
             two sections would be errors. For example, it would be an error
             if code in one section called a function defined in the other
             section.

             The NOCROSSREFS command takes a list of output section names. If
             ld detects any cross references between the sections, it reports
             an error and returns a non-zero exit status. Note that the
             NOCROSSREFS command uses output section names, not input section
             names.

     OUTPUT_ARCH( bfdarch)
             Specify a particular output machine architecture. The argument is
             one of the names used by the BFD library (see Section “BFD”).
             You can see the architecture of an object file by using the
             objdump program with the -f option.

   Assigning Values to Symbols
     You may assign a value to a symbol in a linker script. This will define
     the symbol and place it into the symbol table with a global scope.

     Simple Assignments

     You may assign to a symbol using any of the C assignment operators:

     symbol = expression;

     symbol += expression;

     symbol -= expression;

     symbol *= expression;

     symbol /= expression;

     symbol <<= expression;

     symbol >>= expression;

     symbol &= expression;

     symbol |= expression;

     The first case will define symbol to the value of expression.  In the
     other cases, symbol must already be defined, and the value will be
     adjusted accordingly.

     The special symbol name .  indicates the location counter. You may only
     use this within a SECTIONS command.See Section “Location Counter”.

     The semicolon after expression is required.

     Expressions are defined below; see Expressions.

     You may write symbol assignments as commands in their own right, or as
     statements within a SECTIONS command, or as part of an output section
     description in a SECTIONS command.

     The section of the symbol will be set from the section of the expression;
     for more information, see Expression Section.

     Here is an example showing the three different places that symbol
     assignments may be used:

           floating_point = 0;
           SECTIONS
           {
             .text :
               {
                 *(.text)
                 _etext = .;
               }
             _bdata = (. + 3) & ~ 3;
             .data : { *(.data) }
           }
     In this example, the symbol floating_point will be defined as zero. The
     symbol _etext will be defined as the address following the last .text
     input section. The symbol _bdata will be defined as the address following
     the .text output section aligned upward to a 4 byte boundary.

     PROVIDE

     In some cases, it is desirable for a linker script to define a symbol
     only if it is referenced and is not defined by any object included in the
     link.  For example, traditional linkers defined the symbol etext.
     However, ANSI C requires that the user be able to use etext as a function
     name without encountering an error. The PROVIDE keyword may be used to
     define a symbol, such as etext, only if it is referenced but not defined.
     The syntax is PROVIDE( symbol = expression).

     Here is an example of using PROVIDE to define etext:

           SECTIONS
           {
             .text :
               {
                 *(.text)
                 _etext = .;
                 PROVIDE(etext = .);
               }
           }

     In this example, if the program defines _etext (with a leading
     underscore), the linker will give a multiple definition error.  If, on
     the other hand, the program defines etext (with no leading underscore),
     the linker will silently use the definition in the program. If the
     program references etext but does not define it, the linker will use the
     definition in the linker script.

     PROVIDE_HIDDEN

     Similar to PROVIDE.  For ELF targeted ports, the symbol will be hidden
     and won't be exported.

     Source Code Reference

     Accessing a linker script defined variable from source code is not
     intuitive.  In particular a linker script symbol is not equivalent to a
     variable declaration in a high level language, it is instead a symbol
     that does not have a value.

     Before going further, it is important to note that compilers often
     transform names in the source code into different names when they are
     stored in the symbol table. For example, Fortran compilers commonly
     prepend or append an underscore, and C++ performs extensive name
     mangling.  Therefore there might be a discrepancy between the name of a
     variable as it is used in source code and the name of the same variable
     as it is defined in a linker script. For example in C a linker script
     variable might be referred to as:

             extern int foo;

     But in the linker script it might be defined as:

             _foo = 1000;

     In the remaining examples however it is assumed that no name
     transformation has taken place.

     When a symbol is declared in a high level language such as C, two things
     happen.  The first is that the compiler reserves enough space in the
     program's memory to hold the value of the symbol. The second is that the
     compiler creates an entry in the program's symbol table which holds the
     symbol's address.  ie the symbol table contains the address of the block
     of memory holding the symbol's value. So for example the following C
     declaration, at file scope:

             int foo = 1000;

     creates a entry called foo in the symbol table. This entry holds the
     address of an int sized block of memory where the number 1000 is
     initially stored.

     When a program references a symbol the compiler generates code that first
     accesses the symbol table to find the address of the symbol's memory
     block and then code to read the value from that memory block. So:

             foo = 1;

     looks up the symbol foo in the symbol table, gets the address associated
     with this symbol and then writes the value 1 into that address. Whereas:

             int * a = & foo;

     looks up the symbol foo in the symbol table, gets it address and then
     copies this address into the block of memory associated with the variable
     a.

     Linker scripts symbol declarations, by contrast, create an entry in the
     symbol table but do not assign any memory to them. Thus they are an
     address without a value. So for example the linker script definition:

             foo = 1000;

     creates an entry in the symbol table called foo which holds the address
     of memory location 1000, but nothing special is stored at address 1000.
     This means that you cannot access the value of a linker script defined
     symbol - it has no value - all you can do is access the address of a
     linker script defined symbol.

     Hence when you are using a linker script defined symbol in source code
     you should always take the address of the symbol, and never attempt to
     use its value. For example suppose you want to copy the contents of a
     section of memory called .ROM into a section called .FLASH and the linker
     script contains these declarations:

             start_of_ROM   = .ROM;
             end_of_ROM     = .ROM + sizeof (.ROM) - 1;
             start_of_FLASH = .FLASH;


     Then the C source code to perform the copy would be:

             extern char start_of_ROM, end_of_ROM, start_of_FLASH;

             memcpy (& start_of_FLASH, & start_of_ROM, & end_of_ROM - & start_of_ROM);


     Note the use of the & operators. These are correct.

   SECTIONS Command
     The SECTIONS command tells the linker how to map input sections into
     output sections, and how to place the output sections in memory.

     The format of the SECTIONS command is:

           SECTIONS
           {
             sections-command
             sections-command
             ...
           }

     Each sections-command may of be one of the following:

     ·   an ENTRY command (see Section “Entry Point”)

     ·   a symbol assignment (see Section “Assignments”)

     ·   an output section description

     ·   an overlay description

     The ENTRY command and symbol assignments are permitted inside the
     SECTIONS command for convenience in using the location counter in those
     commands. This can also make the linker script easier to understand
     because you can use those commands at meaningful points in the layout of
     the output file.

     Output section descriptions and overlay descriptions are described below.

     If you do not use a SECTIONS command in your linker script, the linker
     will place each input section into an identically named output section in
     the order that the sections are first encountered in the input files. If
     all input sections are present in the first file, for example, the order
     of sections in the output file will match the order in the first input
     file. The first section will be at address zero.

     Output Section Description

     The full description of an output section looks like this:


           section [address] [(type)] :
             [AT(lma)] [ALIGN(section_align)] [SUBALIGN(subsection_align)]
             {
               output-section-command
               output-section-command
               ...
             } [>region] [AT>lma_region] [:phdr :phdr ...] [=fillexp]


     Most output sections do not use most of the optional section attributes.

     The whitespace around section is required, so that the section name is
     unambiguous. The colon and the curly braces are also required. The line
     breaks and other white space are optional.

     Each output-section-command may be one of the following:

     ·   a symbol assignment (see Section “Assignments”)

     ·   an input section description (see Section “Input Section”)

     ·   data values to include directly (see Section “Output Section Data”)

     ·   a special output section keyword (see Section “Output Section
         Keywords”)

     Output Section Name

     The name of the output section is section.  section must meet the
     constraints of your output format. In formats which only support a
     limited number of sections, such as a.out, the name must be one of the
     names supported by the format ( a.out, for example, allows only .text,
     .data or .bss).  If the output format supports any number of sections,
     but with numbers and not names (as is the case for Oasys), the name
     should be supplied as a quoted numeric string. A section name may consist
     of any sequence of characters, but a name which contains any unusual
     characters such as commas must be quoted.

     The output section name /DISCARD/ is special; Output Section Discarding.

     Output Section Address

     The address is an expression for the VMA (the virtual memory address) of
     the output section.  If you do not provide address, the linker will set
     it based on region if present, or otherwise based on the current value of
     the location counter.

     If you provide address, the address of the output section will be set to
     precisely that. If you provide neither address nor region, then the
     address of the output section will be set to the current value of the
     location counter aligned to the alignment requirements of the output
     section.  The alignment requirement of the output section is the
     strictest alignment of any input section contained within the output
     section.

     For example,

           .text . : { *(.text) }
     and

           .text : { *(.text) }
     are subtly different. The first will set the address of the .text output
     section to the current value of the location counter. The second will set
     it to the current value of the location counter aligned to the strictest
     alignment of a .text input section.

     The address may be an arbitrary expression; Expressions. For example, if
     you want to align the section on a 0x10 byte boundary, so that the lowest
     four bits of the section address are zero, you could do something like
     this:

           .text ALIGN(0x10) : { *(.text) }
     This works because ALIGN returns the current location counter aligned
     upward to the specified value.

     Specifying address for a section will change the value of the location
     counter.

     Input Section Description

     The most common output section command is an input section description.

     The input section description is the most basic linker script operation.
     You use output sections to tell the linker how to lay out your program in
     memory.  You use input section descriptions to tell the linker how to map
     the input files into your memory layout.

     Input Section Basics

     An input section description consists of a file name optionally followed
     by a list of section names in parentheses.

     The file name and the section name may be wildcard patterns, which we
     describe further below (see Section “Input Section Wildcards”).

     The most common input section description is to include all input
     sections with a particular name in the output section. For example, to
     include all input .text sections, you would write:

           *(.text)
     Here the * is a wildcard which matches any file name. To exclude a list
     of files from matching the file name wildcard, EXCLUDE_FILE may be used
     to match all files except the ones specified in the EXCLUDE_FILE list.
     For example:

           (*(EXCLUDE_FILE (*crtend.o *otherfile.o) .ctors))
     will cause all .ctors sections from all files except crtend.o and
     otherfile.o to be included.

     There are two ways to include more than one section:

           *(.text .rdata)
           *(.text) *(.rdata)
     The difference between these is the order in which the .text and .rdata
     input sections will appear in the output section. In the first example,
     they will be intermingled, appearing in the same order as they are found
     in the linker input. In the second example, all .text input sections will
     appear first, followed by all .rdata input sections.

     You can specify a file name to include sections from a particular file.
     You would do this if one or more of your files contain special data that
     needs to be at a particular location in memory. For example:

           data.o(.data)

     If you use a file name without a list of sections, then all sections in
     the input file will be included in the output section. This is not
     commonly done, but it may by useful on occasion. For example:

           data.o

     When you use a file name which does not contain any wild card characters,
     the linker will first see if you also specified the file name on the
     linker command line or in an INPUT command. If you did not, the linker
     will attempt to open the file as an input file, as though it appeared on
     the command line. Note that this differs from an INPUT command, because
     the linker will not search for the file in the archive search path.

     Input Section Wildcard Patterns

     In an input section description, either the file name or the section name
     or both may be wildcard patterns.

     The file name of * seen in many examples is a simple wildcard pattern for
     the file name.

     The wildcard patterns are like those used by the Unix shell.

     *       matches any number of characters

     ?       matches any single character

     [chars]
             matches a single instance of any of the chars; the - character
             may be used to specify a range of characters, as in [a-z] to
             match any lower case letter

     \       quotes the following character

     When a file name is matched with a wildcard, the wildcard characters will
     not match a / character (used to separate directory names on Unix). A
     pattern consisting of a single * character is an exception; it will
     always match any file name, whether it contains a / or not. In a section
     name, the wildcard characters will match a / character.

     File name wildcard patterns only match files which are explicitly
     specified on the command line or in an INPUT command. The linker does not
     search directories to expand wildcards.

     If a file name matches more than one wildcard pattern, or if a file name
     appears explicitly and is also matched by a wildcard pattern, the linker
     will use the first match in the linker script. For example, this sequence
     of input section descriptions is probably in error, because the data.o
     rule will not be used:

           .data : { *(.data) }
           .data1 : { data.o(.data) }

     Normally, the linker will place files and sections matched by wildcards
     in the order in which they are seen during the link. You can change this
     by using the SORT_BY_NAME keyword, which appears before a wildcard
     pattern in parentheses (e.g., SORT_BY_NAME(.text*)).  When the
     SORT_BY_NAME keyword is used, the linker will sort the files or sections
     into ascending order by name before placing them in the output file.

     SORT_BY_ALIGNMENT is very similar to SORT_BY_NAME.  The difference is
     SORT_BY_ALIGNMENT will sort sections into ascending order by alignment
     before placing them in the output file.

     SORT is an alias for SORT_BY_NAME.

     When there are nested section sorting commands in linker script, there
     can be at most 1 level of nesting for section sorting commands.

     1.   SORT_BY_NAME ( SORT_BY_ALIGNMENT (wildcard section pattern)). It
          will sort the input sections by name first, then by alignment if 2
          sections have the same name.

     2.   SORT_BY_ALIGNMENT ( SORT_BY_NAME (wildcard section pattern)). It
          will sort the input sections by alignment first, then by name if 2
          sections have the same alignment.

     3.   SORT_BY_NAME ( SORT_BY_NAME (wildcard section pattern)) is treated
          the same as SORT_BY_NAME (wildcard section pattern).

     4.   SORT_BY_ALIGNMENT ( SORT_BY_ALIGNMENT (wildcard section pattern)) is
          treated the same as SORT_BY_ALIGNMENT (wildcard section pattern).

     5.   All other nested section sorting commands are invalid.

     When both command line section sorting option and linker script section
     sorting command are used, section sorting command always takes precedence
     over the command line option.

     If the section sorting command in linker script isn't nested, the command
     line option will make the section sorting command to be treated as nested
     sorting command.

     1.   SORT_BY_NAME (wildcard section pattern ) with [--sort-sections
          alignment] is equivalent to SORT_BY_NAME ( SORT_BY_ALIGNMENT
          (wildcard section pattern)).

     2.   SORT_BY_ALIGNMENT (wildcard section pattern) with [--sort-section
          name] is equivalent to SORT_BY_ALIGNMENT ( SORT_BY_NAME (wildcard
          section pattern)).

     If the section sorting command in linker script is nested, the command
     line option will be ignored.

     If you ever get confused about where input sections are going, use the -M
     linker option to generate a map file. The map file shows precisely how
     input sections are mapped to output sections.

     This example shows how wildcard patterns might be used to partition
     files.  This linker script directs the linker to place all .text sections
     in .text and all .bss sections in .bss.  The linker will place the .data
     section from all files beginning with an upper case character in .DATA;
     for all other files, the linker will place the .data section in .data.


           SECTIONS {
             .text : { *(.text) }
             .DATA : { [A-Z]*(.data) }
             .data : { *(.data) }
             .bss : { *(.bss) }
           }


     Input Section for Common Symbols

     A special notation is needed for common symbols, because in many object
     file formats common symbols do not have a particular input section. The
     linker treats common symbols as though they are in an input section named
     COMMON.

     You may use file names with the COMMON section just as with any other
     input sections. You can use this to place common symbols from a
     particular input file in one section while common symbols from other
     input files are placed in another section.

     In most cases, common symbols in input files will be placed in the .bss
     section in the output file. For example:

           .bss { *(.bss) *(COMMON) }

     Some object file formats have more than one type of common symbol. For
     example, the MIPS ELF object file format distinguishes standard common
     symbols and small common symbols. In this case, the linker will use a
     different special section name for other types of common symbols. In the
     case of MIPS ELF, the linker uses COMMON for standard common symbols and
     .scommon for small common symbols. This permits you to map the different
     types of common symbols into memory at different locations.

     You will sometimes see [COMMON] in old linker scripts. This notation is
     now considered obsolete. It is equivalent to *(COMMON).

     Input Section and Garbage Collection

     When link-time garbage collection is in use ( --gc-sections), it is often
     useful to mark sections that should not be eliminated. This is
     accomplished by surrounding an input section's wildcard entry with
     KEEP(), as in KEEP(*(.init)) or KEEP(SORT_BY_NAME(*)(.ctors)).

     Input Section Example

     The following example is a complete linker script. It tells the linker to
     read all of the sections from file all.o and place them at the start of
     output section outputa which starts at location 0x10000.  All of section
     .input1 from file foo.o follows immediately, in the same output section.
     All of section .input2 from foo.o goes into output section outputb,
     followed by section .input1 from foo1.o.  All of the remaining .input1
     and .input2 sections from any files are written to output section
     outputc.

           SECTIONS {
             outputa 0x10000 :
               {
               all.o
               foo.o (.input1)
               }


             outputb :
               {
               foo.o (.input2)
               foo1.o (.input1)
               }


             outputc :
               {
               *(.input1)
               *(.input2)
               }
           }


     Output Section Data

     You can include explicit bytes of data in an output section by using
     BYTE, SHORT, LONG, QUAD, or SQUAD as an output section command. Each
     keyword is followed by an expression in parentheses providing the value
     to store (see Section “Expressions”).  The value of the expression is
     stored at the current value of the location counter.

     The BYTE, SHORT, LONG, and QUAD commands store one, two, four, and eight
     bytes (respectively). After storing the bytes, the location counter is
     incremented by the number of bytes stored.

     For example, this will store the byte 1 followed by the four byte value
     of the symbol addr:

           BYTE(1)
           LONG(addr)

     When using a 64 bit host or target, QUAD and SQUAD are the same; they
     both store an 8 byte, or 64 bit, value. When both host and target are 32
     bits, an expression is computed as 32 bits. In this case QUAD stores a 32
     bit value zero extended to 64 bits, and SQUAD stores a 32 bit value sign
     extended to 64 bits.

     If the object file format of the output file has an explicit endianness,
     which is the normal case, the value will be stored in that endianness.
     When the object file format does not have an explicit endianness, as is
     true of, for example, S-records, the value will be stored in the
     endianness of the first input object file.

     Note---these commands only work inside a section description and not
     between them, so the following will produce an error from the linker:

           SECTIONS { .text : { *(.text) } LONG(1) .data : { *(.data) } }
     whereas this will work:

           SECTIONS { .text : { *(.text) ; LONG(1) } .data : { *(.data) } }

     You may use the FILL command to set the fill pattern for the current
     section. It is followed by an expression in parentheses. Any otherwise
     unspecified regions of memory within the section (for example, gaps left
     due to the required alignment of input sections) are filled with the
     value of the expression, repeated as necessary.  A FILL statement covers
     memory locations after the point at which it occurs in the section
     definition; by including more than one FILL statement, you can have
     different fill patterns in different parts of an output section.

     This example shows how to fill unspecified regions of memory with the
     value 0x90:

           FILL(0x90909090)

     The FILL command is similar to the = fillexp output section attribute,
     but it only affects the part of the section following the FILL command,
     rather than the entire section. If both are used, the FILL command takes
     precedence.See Section “Output Section Fill”, for details on the fill
     expression.

     Output Section Keywords

     There are a couple of keywords which can appear as output section
     commands.

     CREATE_OBJECT_SYMBOLS
             The command tells the linker to create a symbol for each input
             file. The name of each symbol will be the name of the
             corresponding input file. The section of each symbol will be the
             output section in which the CREATE_OBJECT_SYMBOLS command
             appears.

             This is conventional for the a.out object file format. It is not
             normally used for any other object file format.

     CONSTRUCTORS
             When linking using the a.out object file format, the linker uses
             an unusual set construct to support C++ global constructors and
             destructors. When linking object file formats which do not
             support arbitrary sections, such as ECOFF and XCOFF, the linker
             will automatically recognize C++ global constructors and
             destructors by name. For these object file formats, the
             CONSTRUCTORS command tells the linker to place constructor
             information in the output section where the CONSTRUCTORS command
             appears. The CONSTRUCTORS command is ignored for other object
             file formats.

             The symbol __CTOR_LIST__ marks the start of the global
             constructors, and the symbol __CTOR_END__ marks the end.
             Similarly, __DTOR_LIST__ and __DTOR_END__ mark the start and end
             of the global destructors. The first word in the list is the
             number of entries, followed by the address of each constructor or
             destructor, followed by a zero word. The compiler must arrange to
             actually run the code.  For these object file formats GNU C++
             normally calls constructors from a subroutine __main; a call to
             __main is automatically inserted into the startup code for main.
             GNU C++ normally runs destructors either by using atexit, or
             directly from the function exit.

             For object file formats such as COFF or ELF which support
             arbitrary section names, GNU C++ will normally arrange to put the
             addresses of global constructors and destructors into the .ctors
             and .dtors sections. Placing the following sequence into your
             linker script will build the sort of table which the GNU C++
             runtime code expects to see.

                         __CTOR_LIST__ = .;
                         LONG((__CTOR_END__ - __CTOR_LIST__) / 4 - 2)
                         *(.ctors)
                         LONG(0)
                         __CTOR_END__ = .;
                         __DTOR_LIST__ = .;
                         LONG((__DTOR_END__ - __DTOR_LIST__) / 4 - 2)
                         *(.dtors)
                         LONG(0)
                         __DTOR_END__ = .;

             If you are using the GNU C++ support for initialization priority,
             which provides some control over the order in which global
             constructors are run, you must sort the constructors at link time
             to ensure that they are executed in the correct order. When using
             the CONSTRUCTORS command, use SORT_BY_NAME(CONSTRUCTORS) instead.
             When using the .ctors and .dtors sections, use
             *(SORT_BY_NAME(.ctors)) and *(SORT_BY_NAME(.dtors)) instead of
             just *(.ctors) and *(.dtors).

             Normally the compiler and linker will handle these issues
             automatically, and you will not need to concern yourself with
             them. However, you may need to consider this if you are using C++
             and writing your own linker scripts.

     Output Section Discarding

     The linker will not create output sections with no contents. This is for
     convenience when referring to input sections that may or may not be
     present in any of the input files. For example:

           .foo : { *(.foo) }
     will only create a .foo section in the output file if there is a .foo
     section in at least one input file, and if the input sections are not all
     empty. Other link script directives that allocate space in an output
     section will also create the output section.

     The linker will ignore address assignments (see Section “Output Section
     Address”) on discarded output sections, except when the linker script
     defines symbols in the output section. In that case the linker will obey
     the address assignments, possibly advancing dot even though the section
     is discarded.

     The special output section name /DISCARD/ may be used to discard input
     sections. Any input sections which are assigned to an output section
     named /DISCARD/ are not included in the output file.

     Output Section Attributes

     We showed above that the full description of an output section looked
     like this:


           section [address] [(type)] :
             [AT(lma)] [ALIGN(section_align)] [SUBALIGN(subsection_align)]
             {
               output-section-command
               output-section-command
               ...
             } [>region] [AT>lma_region] [:phdr :phdr ...] [=fillexp]

     We've already described section, address, and output-section-command.  In
     this section we will describe the remaining section attributes.

     Output Section Type

     Each output section may have a type. The type is a keyword in
     parentheses.  The following types are defined:

     NOLOAD  The section should be marked as not loadable, so that it will not
             be loaded into memory when the program is run.

     DSECT

     COPY

     INFO

     OVERLAY
             These type names are supported for backward compatibility, and
             are rarely used. They all have the same effect: the section
             should be marked as not allocatable, so that no memory is
             allocated for the section when the program is run.

     The linker normally sets the attributes of an output section based on the
     input sections which map into it. You can override this by using the
     section type. For example, in the script sample below, the ROM section is
     addressed at memory location 0 and does not need to be loaded when the
     program is run. The contents of the ROM section will appear in the linker
     output file as usual.


           SECTIONS {
             ROM 0 (NOLOAD) : { ... }
             ...
           }


     Output Section LMA

     Every section has a virtual address (VMA) and a load address (LMA); see
     Basic Script Concepts. The address expression which may appear in an
     output section description sets the VMA (see Section “Output Section
     Address”).

     The expression lma that follows the AT keyword specifies the load address
     of the section.

     Alternatively, with AT> lma_region expression, you may specify a memory
     region for the section's load address.See Section “MEMORY”.  Note that if
     the section has not had a VMA assigned to it then the linker will use the
     lma_region as the VMA region as well.

     If neither AT nor AT> is specified for an allocatable section, the linker
     will set the LMA such that the difference between VMA and LMA for the
     section is the same as the preceding output section in the same region.
     If there is no preceding output section or the section is not
     allocatable, the linker will set the LMA equal to the VMA.See Section
     “Output Section Region”.

     This feature is designed to make it easy to build a ROM image. For
     example, the following linker script creates three output sections: one
     called .text, which starts at 0x1000, one called .mdata, which is loaded
     at the end of the .text section even though its VMA is 0x2000, and one
     called .bss to hold uninitialized data at address 0x3000.  The symbol
     _data is defined with the value 0x2000, which shows that the location
     counter holds the VMA value, not the LMA value.

           SECTIONS
             {
             .text 0x1000 : { *(.text) _etext = . ; }
             .mdata 0x2000 :
               AT ( ADDR (.text) + SIZEOF (.text) )
               { _data = . ; *(.data); _edata = . ;  }
             .bss 0x3000 :
               { _bstart = . ;  *(.bss) *(COMMON) ; _bend = . ;}
           }


     The run-time initialization code for use with a program generated with
     this linker script would include something like the following, to copy
     the initialized data from the ROM image to its runtime address. Notice
     how this code takes advantage of the symbols defined by the linker
     script.

           extern char _etext, _data, _edata, _bstart, _bend;
           char *src = &_etext;
           char *dst = &_data;

           /* ROM has data at end of text; copy it. */
           while (dst < &_edata) {
             *dst++ = *src++;
           }

           /* Zero bss */
           for (dst = &_bstart; dst< &_bend; dst++)
             *dst = 0;


     Forced Output Alignment

     You can increase an output section's alignment by using ALIGN.

     Forced Input Alignment

     You can force input section alignment within an output section by using
     SUBALIGN.  The value specified overrides any alignment given by input
     sections, whether larger or smaller.

     Output Section Region

     You can assign a section to a previously defined region of memory by
     using > region.  See Section.Dq MEMORY .

     Here is a simple example:


           MEMORY { rom : ORIGIN = 0x1000, LENGTH = 0x1000 }
           SECTIONS { ROM : { *(.text) } >rom }


     Output Section Phdr

     You can assign a section to a previously defined program segment by using
     : phdr.  See Section.Dq PHDRS .  If a section is assigned to one or more
     segments, then all subsequent allocated sections will be assigned to
     those segments as well, unless they use an explicitly : phdr modifier.
     You can use :NONE to tell the linker to not put the section in any
     segment at all.

     Here is a simple example:


           PHDRS { text PT_LOAD ; }
           SECTIONS { .text : { *(.text) } :text }


     Output Section Fill

     You can set the fill pattern for an entire section by using = fillexp.
     fillexp is an expression (see Section “Expressions”).  Any otherwise
     unspecified regions of memory within the output section (for example,
     gaps left due to the required alignment of input sections) will be filled
     with the value, repeated as necessary. If the fill expression is a simple
     hex number, ie. a string of hex digit starting with 0x and without a
     trailing k or M, then an arbitrarily long sequence of hex digits can be
     used to specify the fill pattern; Leading zeros become part of the
     pattern too. For all other cases, including extra parentheses or a unary
     +, the fill pattern is the four least significant bytes of the value of
     the expression.  In all cases, the number is big-endian.

     You can also change the fill value with a FILL command in the output
     section commands; (see Section “Output Section Data”).

     Here is a simple example:


           SECTIONS { .text : { *(.text) } =0x90909090 }


     Overlay Description

     An overlay description provides an easy way to describe sections which
     are to be loaded as part of a single memory image but are to be run at
     the same memory address. At run time, some sort of overlay manager will
     copy the overlaid sections in and out of the runtime memory address as
     required, perhaps by simply manipulating addressing bits. This approach
     can be useful, for example, when a certain region of memory is faster
     than another.

     Overlays are described using the OVERLAY command. The OVERLAY command is
     used within a SECTIONS command, like an output section description. The
     full syntax of the OVERLAY command is as follows:


           OVERLAY [start] : [NOCROSSREFS] [AT ( ldaddr )]
             {
               secname1
                 {
                   output-section-command
                   output-section-command
                   ...
                 } [:phdr...] [=fill]
               secname2
                 {
                   output-section-command
                   output-section-command
                   ...
                 } [:phdr...] [=fill]
               ...
             } [>region] [:phdr...] [=fill]


     Everything is optional except OVERLAY (a keyword), and each section must
     have a name ( secname1 and secname2 above). The section definitions
     within the OVERLAY construct are identical to those within the general
     SECTIONS contruct (see Section “SECTIONS”), except that no addresses and
     no memory regions may be defined for sections within an OVERLAY.

     The sections are all defined with the same starting address. The load
     addresses of the sections are arranged such that they are consecutive in
     memory starting at the load address used for the OVERLAY as a whole (as
     with normal section definitions, the load address is optional, and
     defaults to the start address; the start address is also optional, and
     defaults to the current value of the location counter).

     If the NOCROSSREFS keyword is used, and there any references among the
     sections, the linker will report an error. Since the sections all run at
     the same address, it normally does not make sense for one section to
     refer directly to another.See Section “Miscellaneous Commands”.

     For each section within the OVERLAY, the linker automatically provides
     two symbols. The symbol __load_start_ secname is defined as the starting
     load address of the section. The symbol __load_stop_ secname is defined
     as the final load address of the section. Any characters within secname
     which are not legal within C identifiers are removed. C (or assembler)
     code may use these symbols to move the overlaid sections around as
     necessary.

     At the end of the overlay, the value of the location counter is set to
     the start address of the overlay plus the size of the largest section.

     Here is an example. Remember that this would appear inside a SECTIONS
     construct.


             OVERLAY 0x1000 : AT (0x4000)
              {
                .text0 { o1/*.o(.text) }
                .text1 { o2/*.o(.text) }
              }

     This will define both .text0 and .text1 to start at address 0x1000.
     .text0 will be loaded at address 0x4000, and .text1 will be loaded
     immediately after .text0.  The following symbols will be defined if
     referenced: __load_start_text0, __load_stop_text0, __load_start_text1,
     __load_stop_text1.

     C code to copy overlay .text1 into the overlay area might look like the
     following.

             extern char __load_start_text1, __load_stop_text1;
             memcpy ((char *) 0x1000, &__load_start_text1,
                     &__load_stop_text1 - &__load_start_text1);


     Note that the OVERLAY command is just syntactic sugar, since everything
     it does can be done using the more basic commands. The above example
     could have been written identically as follows.

             .text0 0x1000 : AT (0x4000) { o1/*.o(.text) }
             PROVIDE (__load_start_text0 = LOADADDR (.text0));
             PROVIDE (__load_stop_text0 = LOADADDR (.text0) + SIZEOF (.text0));
             .text1 0x1000 : AT (0x4000 + SIZEOF (.text0)) { o2/*.o(.text) }
             PROVIDE (__load_start_text1 = LOADADDR (.text1));
             PROVIDE (__load_stop_text1 = LOADADDR (.text1) + SIZEOF (.text1));
             . = 0x1000 + MAX (SIZEOF (.text0), SIZEOF (.text1));


   MEMORY Command
     The linker's default configuration permits allocation of all available
     memory.  You can override this by using the MEMORY command.

     The MEMORY command describes the location and size of blocks of memory in
     the target.  You can use it to describe which memory regions may be used
     by the linker, and which memory regions it must avoid. You can then
     assign sections to particular memory regions. The linker will set section
     addresses based on the memory regions, and will warn about regions that
     become too full. The linker will not shuffle sections around to fit into
     the available regions.

     A linker script may contain at most one use of the MEMORY command.
     However, you can define as many blocks of memory within it as you wish.
     The syntax is:


           MEMORY
             {
               name [(attr)] : ORIGIN = origin, LENGTH = len
               ...
             }


     The name is a name used in the linker script to refer to the region. The
     region name has no meaning outside of the linker script. Region names are
     stored in a separate name space, and will not conflict with symbol names,
     file names, or section names. Each memory region must have a distinct
     name.

     The attr string is an optional list of attributes that specify whether to
     use a particular memory region for an input section which is not
     explicitly mapped in the linker script. As described in SECTIONS, if you
     do not specify an output section for some input section, the linker will
     create an output section with the same name as the input section. If you
     define region attributes, the linker will use them to select the memory
     region for the output section that it creates.

     The attr string must consist only of the following characters:

     R       Read-only section

     W       Read/write section

     X       Executable section

     A       Allocatable section

     I       Initialized section

     L       Same as I

     !       Invert the sense of any of the preceding attributes

     If a unmapped section matches any of the listed attributes other than !,
     it will be placed in the memory region. The !  attribute reverses this
     test, so that an unmapped section will be placed in the memory region
     only if it does not match any of the listed attributes.

     The origin is an numerical expression for the start address of the memory
     region. The expression must evaluate to a constant and it cannot involve
     any symbols.  The keyword ORIGIN may be abbreviated to org or o (but not,
     for example, ORG).

     The len is an expression for the size in bytes of the memory region. As
     with the origin expression, the expression must be numerical only and
     must evaluate to a constant.  The keyword LENGTH may be abbreviated to
     len or l.

     In the following example, we specify that there are two memory regions
     available for allocation: one starting at 0 for 256 kilobytes, and the
     other starting at 0x40000000 for four megabytes. The linker will place
     into the rom memory region every section which is not explicitly mapped
     into a memory region, and is either read-only or executable. The linker
     will place other sections which are not explicitly mapped into a memory
     region into the ram memory region.

           MEMORY
             {
               rom (rx)  : ORIGIN = 0, LENGTH = 256K
               ram (!rx) : org = 0x40000000, l = 4M
             }


     Once you define a memory region, you can direct the linker to place
     specific output sections into that memory region by using the > region
     output section attribute. For example, if you have a memory region named
     mem, you would use >mem in the output section definition.See Section
     “Output Section Region”.  If no address was specified for the output
     section, the linker will set the address to the next available address
     within the memory region. If the combined output sections directed to a
     memory region are too large for the region, the linker will issue an
     error message.

     It is possible to access the origin and length of a memory in an
     expression via the ORIGIN( memory) and LENGTH( memory) functions:

             _fstack = ORIGIN(ram) + LENGTH(ram) - 4;


   PHDRS Command
     The ELF object file format uses program headers, also knows as segments.
     The program headers describe how the program should be loaded into
     memory.  You can print them out by using the objdump program with the -p
     option.

     When you run an ELF program on a native ELF system, the system loader
     reads the program headers in order to figure out how to load the program.
     This will only work if the program headers are set correctly. This manual
     does not describe the details of how the system loader interprets program
     headers; for more information, see the ELF ABI.

     The linker will create reasonable program headers by default. However, in
     some cases, you may need to specify the program headers more precisely.
     You may use the PHDRS command for this purpose. When the linker sees the
     PHDRS command in the linker script, it will not create any program
     headers other than the ones specified.

     The linker only pays attention to the PHDRS command when generating an
     ELF output file. In other cases, the linker will simply ignore PHDRS.

     This is the syntax of the PHDRS command. The words PHDRS, FILEHDR, AT,
     and FLAGS are keywords.

           PHDRS
           {
             name type [ FILEHDR ] [ PHDRS ] [ AT ( address ) ]
                   [ FLAGS ( flags ) ] ;
           }


     The name is used only for reference in the SECTIONS command of the linker
     script. It is not put into the output file. Program header names are
     stored in a separate name space, and will not conflict with symbol names,
     file names, or section names. Each program header must have a distinct
     name.

     Certain program header types describe segments of memory which the system
     loader will load from the file. In the linker script, you specify the
     contents of these segments by placing allocatable output sections in the
     segments.  You use the : phdr output section attribute to place a section
     in a particular segment.See Section “Output Section Phdr”.

     It is normal to put certain sections in more than one segment. This
     merely implies that one segment of memory contains another. You may
     repeat : phdr, using it once for each segment which should contain the
     section.

     If you place a section in one or more segments using : phdr, then the
     linker will place all subsequent allocatable sections which do not
     specify : phdr in the same segments. This is for convenience, since
     generally a whole set of contiguous sections will be placed in a single
     segment. You can use :NONE to override the default segment and tell the
     linker to not put the section in any segment at all.

     You may use the FILEHDR and PHDRS keywords appear after the program
     header type to further describe the contents of the segment. The FILEHDR
     keyword means that the segment should include the ELF file header. The
     PHDRS keyword means that the segment should include the ELF program
     headers themselves.

     The type may be one of the following. The numbers indicate the value of
     the keyword.

     PT_NULL (0)
             Indicates an unused program header.

     PT_LOAD (1)
             Indicates that this program header describes a segment to be
             loaded from the file.

     PT_DYNAMIC (2)
             Indicates a segment where dynamic linking information can be
             found.

     PT_INTERP (3)
             Indicates a segment where the name of the program interpreter may
             be found.

     PT_NOTE (4)
             Indicates a segment holding note information.

     PT_SHLIB (5)
             A reserved program header type, defined but not specified by the
             ELF ABI.

     PT_PHDR (6)
             Indicates a segment where the program headers may be found.

     expression
             An expression giving the numeric type of the program header. This
             may be used for types not defined above.

     You can specify that a segment should be loaded at a particular address
     in memory by using an AT expression. This is identical to the AT command
     used as an output section attribute (see Section “Output Section LMA”).
     The AT command for a program header overrides the output section
     attribute.

     The linker will normally set the segment flags based on the sections
     which comprise the segment. You may use the FLAGS keyword to explicitly
     specify the segment flags. The value of flags must be an integer. It is
     used to set the p_flags field of the program header.

     Here is an example of PHDRS.  This shows a typical set of program headers
     used on a native ELF system.

           PHDRS
           {
             headers PT_PHDR PHDRS ;
             interp PT_INTERP ;
             text PT_LOAD FILEHDR PHDRS ;
             data PT_LOAD ;
             dynamic PT_DYNAMIC ;
           }

           SECTIONS
           {
             . = SIZEOF_HEADERS;
             .interp : { *(.interp) } :text :interp
             .text : { *(.text) } :text
             .rodata : { *(.rodata) } /* defaults to :text */
             ...
             . = . + 0x1000; /* move to a new page in memory */
             .data : { *(.data) } :data
             .dynamic : { *(.dynamic) } :data :dynamic
             ...
           }


   VERSION Command
     The linker supports symbol versions when using ELF. Symbol versions are
     only useful when using shared libraries. The dynamic linker can use
     symbol versions to select a specific version of a function when it runs a
     program that may have been linked against an earlier version of the
     shared library.

     You can include a version script directly in the main linker script, or
     you can supply the version script as an implicit linker script. You can
     also use the --version-script linker option.

     The syntax of the VERSION command is simply

           VERSION { version-script-commands }

     The format of the version script commands is identical to that used by
     Sun's linker in Solaris 2.5. The version script defines a tree of version
     nodes.  You specify the node names and interdependencies in the version
     script. You can specify which symbols are bound to which version nodes,
     and you can reduce a specified set of symbols to local scope so that they
     are not globally visible outside of the shared library.

     The easiest way to demonstrate the version script language is with a few
     examples.

           VERS_1.1 {
                    global:
                            foo1;
                    local:
                            old*;
                            original*;
                            new*;
           };

           VERS_1.2 {
                            foo2;
           } VERS_1.1;

           VERS_2.0 {
                            bar1; bar2;
                    extern "C++" {
                            ns::*;
                            "int f(int, double)";
                    }
           } VERS_1.2;

     This example version script defines three version nodes. The first
     version node defined is VERS_1.1; it has no other dependencies. The
     script binds the symbol foo1 to VERS_1.1.  It reduces a number of symbols
     to local scope so that they are not visible outside of the shared
     library; this is done using wildcard patterns, so that any symbol whose
     name begins with old, original, or new is matched. The wildcard patterns
     available are the same as those used in the shell when matching filenames
     (also known as “globbing”). However, if you specify the symbol name
     inside double quotes, then the name is treated as literal, rather than as
     a glob pattern.

     Next, the version script defines node VERS_1.2.  This node depends upon
     VERS_1.1.  The script binds the symbol foo2 to the version node VERS_1.2.

     Finally, the version script defines node VERS_2.0.  This node depends
     upon VERS_1.2.  The scripts binds the symbols bar1 and bar2 are bound to
     the version node VERS_2.0.

     When the linker finds a symbol defined in a library which is not
     specifically bound to a version node, it will effectively bind it to an
     unspecified base version of the library. You can bind all otherwise
     unspecified symbols to a given version node by using global: *; somewhere
     in the version script.

     The names of the version nodes have no specific meaning other than what
     they might suggest to the person reading them. The 2.0 version could just
     as well have appeared in between 1.1 and 1.2.  However, this would be a
     confusing way to write a version script.

     Node name can be omitted, provided it is the only version node in the
     version script. Such version script doesn't assign any versions to
     symbols, only selects which symbols will be globally visible out and
     which won't.

           { global: foo; bar; local: *; };

     When you link an application against a shared library that has versioned
     symbols, the application itself knows which version of each symbol it
     requires, and it also knows which version nodes it needs from each shared
     library it is linked against. Thus at runtime, the dynamic loader can
     make a quick check to make sure that the libraries you have linked
     against do in fact supply all of the version nodes that the application
     will need to resolve all of the dynamic symbols. In this way it is
     possible for the dynamic linker to know with certainty that all external
     symbols that it needs will be resolvable without having to search for
     each symbol reference.

     The symbol versioning is in effect a much more sophisticated way of doing
     minor version checking that SunOS does. The fundamental problem that is
     being addressed here is that typically references to external functions
     are bound on an as-needed basis, and are not all bound when the
     application starts up.  If a shared library is out of date, a required
     interface may be missing; when the application tries to use that
     interface, it may suddenly and unexpectedly fail. With symbol versioning,
     the user will get a warning when they start their program if the
     libraries being used with the application are too old.

     There are several GNU extensions to Sun's versioning approach. The first
     of these is the ability to bind a symbol to a version node in the source
     file where the symbol is defined instead of in the versioning script.
     This was done mainly to reduce the burden on the library maintainer. You
     can do this by putting something like:

           __asm__(".symver original_foo,foo@VERS_1.1");
     in the C source file. This renames the function original_foo to be an
     alias for foo bound to the version node VERS_1.1.  The local: directive
     can be used to prevent the symbol original_foo from being exported. A
     .symver directive takes precedence over a version script.

     The second GNU extension is to allow multiple versions of the same
     function to appear in a given shared library. In this way you can make an
     incompatible change to an interface without increasing the major version
     number of the shared library, while still allowing applications linked
     against the old interface to continue to function.

     To do this, you must use multiple .symver directives in the source file.
     Here is an example:

           __asm__(".symver original_foo,foo@");
           __asm__(".symver old_foo,foo@VERS_1.1");
           __asm__(".symver old_foo1,foo@VERS_1.2");
           __asm__(".symver new_foo,foo@@VERS_2.0");

     In this example, foo@ represents the symbol foo bound to the unspecified
     base version of the symbol. The source file that contains this example
     would define 4 C functions: original_foo, old_foo, old_foo1, and new_foo.

     When you have multiple definitions of a given symbol, there needs to be
     some way to specify a default version to which external references to
     this symbol will be bound. You can do this with the foo@@VERS_2.0 type of
     .symver directive. You can only declare one version of a symbol as the
     default in this manner; otherwise you would effectively have multiple
     definitions of the same symbol.

     If you wish to bind a reference to a specific version of the symbol
     within the shared library, you can use the aliases of convenience (i.e.,
     old_foo), or you can use the .symver directive to specifically bind to an
     external version of the function in question.

     You can also specify the language in the version script:

           VERSION extern "lang" { version-script-commands }

     The supported lang s are C, C++, and Java.  The linker will iterate over
     the list of symbols at the link time and demangle them according to lang
     before matching them to the patterns specified in
     version-script-commands.

     Demangled names may contains spaces and other special characters. As
     described above, you can use a glob pattern to match demangled names, or
     you can use a double-quoted string to match the string exactly. In the
     latter case, be aware that minor differences (such as differing
     whitespace) between the version script and the demangler output will
     cause a mismatch. As the exact string generated by the demangler might
     change in the future, even if the mangled name does not, you should check
     that all of your version directives are behaving as you expect when you
     upgrade.

   Expressions in Linker Scripts
     The syntax for expressions in the linker script language is identical to
     that of C expressions. All expressions are evaluated as integers. All
     expressions are evaluated in the same size, which is 32 bits if both the
     host and target are 32 bits, and is otherwise 64 bits.

     You can use and set symbol values in expressions.

     The linker defines several special purpose builtin functions for use in
     expressions.

     Constants

     All constants are integers.

     As in C, the linker considers an integer beginning with 0 to be octal,
     and an integer beginning with 0x or 0X to be hexadecimal. The linker
     considers other integers to be decimal.

     In addition, you can use the suffixes K and M to scale a constant by 1024
     or 1024*1024 respectively. For example, the following all refer to the
     same quantity:

           _fourk_1 = 4K;
           _fourk_2 = 4096;
           _fourk_3 = 0x1000;

     Symbol Names

     Unless quoted, symbol names start with a letter, underscore, or period
     and may include letters, digits, underscores, periods, and hyphens.
     Unquoted symbol names must not conflict with any keywords. You can
     specify a symbol which contains odd characters or has the same name as a
     keyword by surrounding the symbol name in double quotes:

           "SECTION" = 9;
           "with a space" = "also with a space" + 10;

     Since symbols can contain many non-alphabetic characters, it is safest to
     delimit symbols with spaces. For example, A-B is one symbol, whereas A -
     B is an expression involving subtraction.

     Orphan Sections

     Orphan sections are sections present in the input files which are not
     explicitly placed into the output file by the linker script. The linker
     will still copy these sections into the output file, but it has to guess
     as to where they should be placed. The linker uses a simple heuristic to
     do this. It attempts to place orphan sections after non-orphan sections
     of the same attribute, such as code vs data, loadable vs non-loadable,
     etc. If there is not enough room to do this then it places at the end of
     the file.

     For ELF targets, the attribute of the section includes section type as
     well as section flag.

     The Location Counter

     The special linker variable dot .  always contains the current output
     location counter. Since the .  always refers to a location in an output
     section, it may only appear in an expression within a SECTIONS command.
     The .  symbol may appear anywhere that an ordinary symbol is allowed in
     an expression.

     Assigning a value to .  will cause the location counter to be moved. This
     may be used to create holes in the output section. The location counter
     may not be moved backwards inside an output section, and may not be moved
     backwards outside of an output section if so doing creates areas with
     overlapping LMAs.

           SECTIONS
           {
             output :
               {
                 file1(.text)
                 . = . + 1000;
                 file2(.text)
                 . += 1000;
                 file3(.text)
               } = 0x12345678;
           }
     In the previous example, the .text section from file1 is located at the
     beginning of the output section output.  It is followed by a 1000 byte
     gap. Then the .text section from file2 appears, also with a 1000 byte gap
     following before the .text section from file3.  The notation = 0x12345678
     specifies what data to write in the gaps (see Section “Output Section
     Fill”).

     Note: .  actually refers to the byte offset from the start of the current
     containing object. Normally this is the SECTIONS statement, whose start
     address is 0, hence .  can be used as an absolute address. If .  is used
     inside a section description however, it refers to the byte offset from
     the start of that section, not an absolute address. Thus in a script like
     this:

           SECTIONS
           {
               . = 0x100
               .text: {
                 *(.text)
                 . = 0x200
               }
               . = 0x500
               .data: {
                 *(.data)
                 . += 0x600
               }
           }

     The .text section will be assigned a starting address of 0x100 and a size
     of exactly 0x200 bytes, even if there is not enough data in the .text
     input sections to fill this area. (If there is too much data, an error
     will be produced because this would be an attempt to move .  backwards).
     The .data section will start at 0x500 and it will have an extra 0x600
     bytes worth of space after the end of the values from the .data input
     sections and before the end of the .data output section itself.

     Setting symbols to the value of the location counter outside of an output
     section statement can result in unexpected values if the linker needs to
     place orphan sections. For example, given the following:

           SECTIONS
           {
               start_of_text = . ;
               .text: { *(.text) }
               end_of_text = . ;

               start_of_data = . ;
               .data: { *(.data) }
               end_of_data = . ;
           }

     If the linker needs to place some input section, e.g.  .rodata, not
     mentioned in the script, it might choose to place that section between
     .text and .data.  You might think the linker should place .rodata on the
     blank line in the above script, but blank lines are of no particular
     significance to the linker. As well, the linker doesn't associate the
     above symbol names with their sections. Instead, it assumes that all
     assignments or other statements belong to the previous output section,
     except for the special case of an assignment to ..  I.e., the linker will
     place the orphan .rodata section as if the script was written as follows:

           SECTIONS
           {
               start_of_text = . ;
               .text: { *(.text) }
               end_of_text = . ;

               start_of_data = . ;
               .rodata: { *(.rodata) }
               .data: { *(.data) }
               end_of_data = . ;
           }

     This may or may not be the script author's intention for the value of
     start_of_data.  One way to influence the orphan section placement is to
     assign the location counter to itself, as the linker assumes that an
     assignment to .  is setting the start address of a following output
     section and thus should be grouped with that section. So you could write:

           SECTIONS
           {
               start_of_text = . ;
               .text: { *(.text) }
               end_of_text = . ;

               . = . ;
               start_of_data = . ;
               .data: { *(.data) }
               end_of_data = . ;
           }

     Now, the orphan .rodata section will be placed between end_of_text and
     start_of_data.

     Operators

     The linker recognizes the standard C set of arithmetic operators, with
     the standard bindings and precedence levels:

           precedence      associativity   Operators                Notes
           (highest)
           1               left            !  -  ~                  (1)
           2               left            *  /  %
           3               left            +  -
           4               left            >>  <<
           5               left            ==  !=  >  <  <=  >=
           6               left            &
           7               left            |
           8               left            &&
           9               left            ||
           10              right           ? :
           11              right           &=  +=  -=  *=  /=       (2)
           (lowest)
     Notes: (1) Prefix operators (2)See Section “Assignments”.

     Evaluation

     The linker evaluates expressions lazily. It only computes the value of an
     expression when absolutely necessary.

     The linker needs some information, such as the value of the start address
     of the first section, and the origins and lengths of memory regions, in
     order to do any linking at all. These values are computed as soon as
     possible when the linker reads in the linker script.

     However, other values (such as symbol values) are not known or needed
     until after storage allocation. Such values are evaluated later, when
     other information (such as the sizes of output sections) is available for
     use in the symbol assignment expression.

     The sizes of sections cannot be known until after allocation, so
     assignments dependent upon these are not performed until after
     allocation.

     Some expressions, such as those depending upon the location counter .,
     must be evaluated during section allocation.

     If the result of an expression is required, but the value is not
     available, then an error results. For example, a script like the
     following


           SECTIONS
             {
               .text 9+this_isnt_constant :
                 { *(.text) }
             }

     will cause the error message non constant expression for initial address.

     The Section of an Expression

     When the linker evaluates an expression, the result is either absolute or
     relative to some section. A relative expression is expressed as a fixed
     offset from the base of a section.

     The position of the expression within the linker script determines
     whether it is absolute or relative. An expression which appears within an
     output section definition is relative to the base of the output section.
     An expression which appears elsewhere will be absolute.

     A symbol set to a relative expression will be relocatable if you request
     relocatable output using the -r option. That means that a further link
     operation may change the value of the symbol. The symbol's section will
     be the section of the relative expression.

     A symbol set to an absolute expression will retain the same value through
     any further link operation. The symbol will be absolute, and will not
     have any particular associated section.

     You can use the builtin function ABSOLUTE to force an expression to be
     absolute when it would otherwise be relative.  For example, to create an
     absolute symbol set to the address of the end of the output section
     .data:

           SECTIONS
             {
               .data : { *(.data) _edata = ABSOLUTE(.); }
             }
     If ABSOLUTE were not used, _edata would be relative to the .data section.

     Builtin Functions

     The linker script language includes a number of builtin functions for use
     in linker script expressions.

     ABSOLUTE( exp)
             Return the absolute (non-relocatable, as opposed to non-negative)
             value of the expression exp.  Primarily useful to assign an
             absolute value to a symbol within a section definition, where
             symbol values are normally section relative.See Section
             “Expression Section”.

     ADDR( section)
             Return the absolute address (the VMA) of the named section.  Your
             script must previously have defined the location of that section.
             In the following example, symbol_1 and symbol_2 are assigned
             identical values:


                   SECTIONS { ...
                     .output1 :
                       {
                       start_of_output_1 = ABSOLUTE(.);
                       ...
                       }
                     .output :
                       {
                       symbol_1 = ADDR(.output1);
                       symbol_2 = start_of_output_1;
                       }
                   ... }


     ALIGN( align)

     ALIGN( exp, align)
             Return the location counter ( .)  or arbitrary expression aligned
             to the next align boundary. The single operand ALIGN doesn't
             change the value of the location counter---it just does
             arithmetic on it. The two operand ALIGN allows an arbitrary
             expression to be aligned upwards ( ALIGN( align) is equivalent to
             ALIGN(., align)).

             Here is an example which aligns the output .data section to the
             next 0x2000 byte boundary after the preceding section and sets a
             variable within the section to the next 0x8000 boundary after the
             input sections:


                   SECTIONS { ...
                     .data ALIGN(0x2000): {
                       *(.data)
                       variable = ALIGN(0x8000);
                     }
                   ... }

             The first use of ALIGN in this example specifies the location of
             a section because it is used as the optional address attribute of
             a section definition (see Section “Output Section Address”).  The
             second use of ALIGN is used to defines the value of a symbol.

             The builtin function NEXT is closely related to ALIGN.

     ALIGNOF( section)
             Return the alignment in bytes of the named section, if that
             section has been allocated. If the section has not been allocated
             when this is evaluated, the linker will report an error. In the
             following example, the alignment of the .output section is stored
             as the first value in that section.


                   SECTIONS{ ...
                     .output {
                       LONG (ALIGNOF (.output))
                       ...
                       }
                   ... }


     BLOCK( exp)
             This is a synonym for ALIGN, for compatibility with older linker
             scripts. It is most often seen when setting the address of an
             output section.

     DATA_SEGMENT_ALIGN( maxpagesize, commonpagesize)
             This is equivalent to either

                   (ALIGN(maxpagesize) + (. & (maxpagesize - 1)))
             or

                   (ALIGN(maxpagesize) + (. & (maxpagesize - commonpagesize)))
             depending on whether the latter uses fewer commonpagesize sized
             pages for the data segment (area between the result of this
             expression and DATA_SEGMENT_END) than the former or not. If the
             latter form is used, it means commonpagesize bytes of runtime
             memory will be saved at the expense of up to commonpagesize
             wasted bytes in the on-disk file.

             This expression can only be used directly in SECTIONS commands,
             not in any output section descriptions and only once in the
             linker script.  commonpagesize should be less or equal to
             maxpagesize and should be the system page size the object wants
             to be optimized for (while still working on system page sizes up
             to maxpagesize).

             Example:

                     . = DATA_SEGMENT_ALIGN(0x10000, 0x2000);

     DATA_SEGMENT_END( exp)
             This defines the end of data segment for DATA_SEGMENT_ALIGN
             evaluation purposes.

                     . = DATA_SEGMENT_END(.);

     DATA_SEGMENT_RELRO_END( offset, exp)
             This defines the end of the PT_GNU_RELRO segment when -z relro
             option is used. Second argument is returned. When -z relro option
             is not present, DATA_SEGMENT_RELRO_END does nothing, otherwise
             DATA_SEGMENT_ALIGN is padded so that exp + offset is aligned to
             the most commonly used page boundary for particular target.  If
             present in the linker script, it must always come in between
             DATA_SEGMENT_ALIGN and DATA_SEGMENT_END.

                     . = DATA_SEGMENT_RELRO_END(24, .);

     DEFINED( symbol)
             Return 1 if symbol is in the linker global symbol table and is
             defined before the statement using DEFINED in the script,
             otherwise return 0. You can use this function to provide default
             values for symbols. For example, the following script fragment
             shows how to set a global symbol begin to the first location in
             the .text section---but if a symbol called begin already existed,
             its value is preserved:

                   SECTIONS { ...
                     .text : {
                       begin = DEFINED(begin) ? begin : . ;
                       ...
                     }
                     ...
                   }


     LENGTH( memory)
             Return the length of the memory region named memory.

     LOADADDR( section)
             Return the absolute LMA of the named section.  This is normally
             the same as ADDR, but it may be different if the AT attribute is
             used in the output section definition (see Section “Output
             Section LMA”).

     MAX( exp1, exp2)
             Returns the maximum of exp1 and exp2.

     MIN( exp1, exp2)
             Returns the minimum of exp1 and exp2.

     NEXT( exp)
             Return the next unallocated address that is a multiple of exp.
             This function is closely related to ALIGN( exp); unless you use
             the MEMORY command to define discontinuous memory for the output
             file, the two functions are equivalent.

     ORIGIN( memory)
             Return the origin of the memory region named memory.

     SEGMENT_START( segment, default)
             Return the base address of the named segment.  If an explicit
             value has been given for this segment (with a command-line -T
             option) that value will be returned; otherwise the value will be
             default.  At present, the -T command-line option can only be used
             to set the base address for the “text”, “data”, and “bss”
             sections, but you use SEGMENT_START with any segment name.

     SIZEOF( section)
             Return the size in bytes of the named section, if that section
             has been allocated. If the section has not been allocated when
             this is evaluated, the linker will report an error. In the
             following example, symbol_1 and symbol_2 are assigned identical
             values:


                   SECTIONS{ ...
                     .output {
                       .start = . ;
                       ...
                       .end = . ;
                       }
                     symbol_1 = .end - .start ;
                     symbol_2 = SIZEOF(.output);
                   ... }


     SIZEOF_HEADERS

     sizeof_headers
             Return the size in bytes of the output file's headers. This is
             information which appears at the start of the output file. You
             can use this number when setting the start address of the first
             section, if you choose, to facilitate paging.

             When producing an ELF output file, if the linker script uses the
             SIZEOF_HEADERS builtin function, the linker must compute the
             number of program headers before it has determined all the
             section addresses and sizes. If the linker later discovers that
             it needs additional program headers, it will report an error not
             enough room for program headers.  To avoid this error, you must
             avoid using the SIZEOF_HEADERS function, or you must rework your
             linker script to avoid forcing the linker to use additional
             program headers, or you must define the program headers yourself
             using the PHDRS command (see Section “PHDRS”).

   Implicit Linker Scripts
     If you specify a linker input file which the linker can not recognize as
     an object file or an archive file, it will try to read the file as a
     linker script.  If the file can not be parsed as a linker script, the
     linker will report an error.

     An implicit linker script will not replace the default linker script.

     Typically an implicit linker script would contain only symbol
     assignments, or the INPUT, GROUP, or VERSION commands.

     Any input files read because of an implicit linker script will be read at
     the position in the command line where the implicit linker script was
     read.  This can affect archive searching.

Machine Dependent Features
     ld has additional features on some platforms; the following sections
     describe them. Machines where ld has no additional functionality are not
     listed.

   ld(and) the H8/300
     For the H8/300, ld can perform these global optimizations when you
     specify the --relax command-line option.

     relaxing address modes
             ld finds all jsr and jmp instructions whose targets are within
             eight bits, and turns them into eight-bit program-counter
             relative bsr and bra instructions, respectively.

     synthesizing instructions
             ld finds all mov.b instructions which use the sixteen-bit
             absolute address form, but refer to the top page of memory, and
             changes them to use the eight-bit address form.  (That is: the
             linker turns mov.b @ aa:16 into mov.b @ aa:8 whenever the address
             aa is in the top page of memory).

     bit manipulation instructions
             ld finds all bit manipulation instructions like band, bclr,
             biand, bild, bior, bist, bixor, bld, bnot, bor, bset, bst, btst,
             bxor which use 32 bit and 16 bit absolute address form, but refer
             to the top page of memory, and changes them to use the 8 bit
             address form. (That is: the linker turns bset #xx:3, @ aa:32 into
             bset #xx:3, @ aa:8 whenever the address aa is in the top page of
             memory).

     system control instructions
             ld finds all ldc.w, stc.w instructions which use the 32 bit
             absolute address form, but refer to the top page of memory, and
             changes them to use 16 bit address form. (That is: the linker
             turns ldc.w @ aa:32,ccr into ldc.w @ aa:16,ccr whenever the
             address aa is in the top page of memory).

   ld(and) the Intel 960 Family
     You can use the -A architecture command line option to specify one of the
     two-letter names identifying members of the 960 family; the option
     specifies the desired output target, and warns of any incompatible
     instructions in the input files. It also modifies the linker's search
     strategy for archive libraries, to support the use of libraries specific
     to each particular architecture, by including in the search loop names
     suffixed with the string identifying the architecture.

     For example, if your ld command line included -ACA as well as -ltry , the
     linker would look (in its built-in search paths, and in any paths you
     specify with -L) for a library with the names

           try
           libtry.a
           tryca
           libtryca.a


     The first two possibilities would be considered in any event; the last
     two are due to the use of -ACA .

     You can meaningfully use -A more than once on a command line, since the
     960 architecture family allows combination of target architectures; each
     use will add another pair of name variants to search for when -l
     specifies a library.

     ld supports the --relax option for the i960 family. If you specify
     --relax, ld finds all balx and calx instructions whose targets are within
     24 bits, and turns them into 24-bit program-counter relative bal and cal
     instructions, respectively.  ld also turns cal instructions into bal
     instructions when it determines that the target subroutine is a leaf
     routine (that is, the target subroutine does not itself call any
     subroutines).

   ld(and) the Motorola 68HC11 and 68HC12 families
     Linker Relaxation

     For the Motorola 68HC11, ld can perform these global optimizations when
     you specify the --relax command-line option.

     relaxing address modes
             ld finds all jsr and jmp instructions whose targets are within
             eight bits, and turns them into eight-bit program-counter
             relative bsr and bra instructions, respectively.

             ld also looks at all 16-bit extended addressing modes and
             transforms them in a direct addressing mode when the address is
             in page 0 (between 0 and 0x0ff).

     relaxing gcc instruction group
             When gcc is called with [-mrelax], it can emit group of
             instructions that the linker can optimize to use a 68HC11 direct
             addressing mode. These instructions consists of bclr or bset
             instructions.

     Trampoline Generation

     For 68HC11 and 68HC12, ld can generate trampoline code to call a far
     function using a normal jsr instruction. The linker will also change the
     relocation to some far function to use the trampoline address instead of
     the function address. This is typically the case when a pointer to a
     function is taken. The pointer will in fact point to the function
     trampoline.

     The --pic-veneer switch makes the linker use PIC sequences for ARM/Thumb
     interworking veneers, even if the rest of the binary is not PIC. This
     avoids problems on uClinux targets where --emit-relocs is used to
     generate relocatable binaries.

   ld(and) the ARM family
     For the ARM, ld will generate code stubs to allow functions calls between
     ARM and Thumb code.  These stubs only work with code that has been
     compiled and assembled with the -mthumb-interwork command line option. If
     it is necessary to link with old ARM object files or libraries, which
     have not been compiled with the -mthumb-interwork option then the
     --support-old-code command line switch should be given to the linker.
     This will make it generate larger stub functions which will work with
     non-interworking aware ARM code.  Note, however, the linker does not
     support generating stubs for function calls to non-interworking aware
     Thumb code.

     The --thumb-entry switch is a duplicate of the generic --entry switch, in
     that it sets the program's starting address. But it also sets the bottom
     bit of the address, so that it can be branched to using a BX instruction,
     and the program will start executing in Thumb mode straight away.

     The --be8 switch instructs ld to generate BE8 format executables. This
     option is only valid when linking big-endian objects. The resulting image
     will contain big-endian data and little-endian code.

     The R_ARM_TARGET1 relocation is typically used for entries in the
     .init_array section. It is interpreted as either R_ARM_REL32 or
     R_ARM_ABS32, depending on the target. The --target1-rel and --target1-abs
     switches override the default.

     The --target2=type switch overrides the default definition of the
     R_ARM_TARGET2 relocation. Valid values for type, their meanings, and
     target defaults are as follows:

     rel     R_ARM_REL32 (arm*-*-elf, arm*-*-eabi)

     abs     R_ARM_ABS32 (arm*-*-symbianelf)

     got-rel
             R_ARM_GOT_PREL (arm*-*-linux, arm*-*-*bsd)

     The R_ARM_V4BX relocation (defined by the ARM AAELF specification)
     enables objects compiled for the ARMv4 architecture to be interworking-
     safe when linked with other objects compiled for ARMv4t, but also allows
     pure ARMv4 binaries to be built from the same ARMv4 objects.

     In the latter case, the switch [--fix-v4bx] must be passed to the linker,
     which causes v4t BX rM instructions to be rewritten as MOV PC,rM, since
     v4 processors do not have a BX instruction.

     In the former case, the switch should not be used, and R_ARM_V4BX
     relocations are ignored.

     The --use-blx switch enables the linker to use ARM/Thumb BLX instructions
     (available on ARMv5t and above) in various situations. Currently it is
     used to perform calls via the PLT from Thumb code using BLX rather than
     using BX and a mode-switching stub before each PLT entry. This should
     lead to such calls executing slightly faster.

     This option is enabled implicitly for SymbianOS, so there is no need to
     specify it if you are using that target.

     The --vfp11-denorm-fix switch enables a link-time workaround for a bug in
     certain VFP11 coprocessor hardware, which sometimes allows instructions
     with denorm operands (which must be handled by support code) to have
     those operands overwritten by subsequent instructions before the support
     code can read the intended values.

     The bug may be avoided in scalar mode if you allow at least one
     intervening instruction between a VFP11 instruction which uses a register
     and another instruction which writes to the same register, or at least
     two intervening instructions if vector mode is in use. The bug only
     affects full-compliance floating-point mode: you do not need this
     workaround if you are using "runfast" mode. Please contact ARM for
     further details.

     If you know you are using buggy VFP11 hardware, you can enable this
     workaround by specifying the linker option --vfp-denorm-fix=scalar if you
     are using the VFP11 scalar mode only, or --vfp-denorm-fix=vector if you
     are using vector mode (the latter also works for scalar code). The
     default is --vfp-denorm-fix=none.

     If the workaround is enabled, instructions are scanned for potentially-
     troublesome sequences, and a veneer is created for each such sequence
     which may trigger the erratum. The veneer consists of the first
     instruction of the sequence and a branch back to the subsequent
     instruction. The original instruction is then replaced with a branch to
     the veneer. The extra cycles required to call and return from the veneer
     are sufficient to avoid the erratum in both the scalar and vector cases.

     The --no-enum-size-warning switch prevents the linker from warning when
     linking object files that specify incompatible EABI enumeration size
     attributes. For example, with this switch enabled, linking of an object
     file using 32-bit enumeration values with another using enumeration
     values fitted into the smallest possible space will not be diagnosed.

   ld(and) HPPA 32-bit ELF Support
     When generating a shared library, ld will by default generate import
     stubs suitable for use with a single sub-space application. The
     --multi-subspace switch causes ld to generate export stubs, and different
     (larger) import stubs suitable for use with multiple sub-spaces.

     Long branch stubs and import/export stubs are placed by ld in stub
     sections located between groups of input sections.  --stub-group-size
     specifies the maximum size of a group of input sections handled by one
     stub section. Since branch offsets are signed, a stub section may serve
     two groups of input sections, one group before the stub section, and one
     group after it. However, when using conditional branches that require
     stubs, it may be better (for branch prediction) that stub sections only
     serve one group of input sections. A negative value for N chooses this
     scheme, ensuring that branches to stubs always use a negative offset. Two
     special values of N are recognized, 1 and -1.  These both instruct ld to
     automatically size input section groups for the branch types detected,
     with the same behaviour regarding stub placement as other positive or
     negative values of N respectively.

     Note that --stub-group-size does not split input sections. A single input
     section larger than the group size specified will of course create a
     larger group (of one section). If input sections are too large, it may
     not be possible for a branch to reach its stub.

   ld and MMIX
     For MMIX, there is a choice of generating ELF object files or mmo object
     files when linking. The simulator mmix understands the mmo format. The
     binutils objcopy utility can translate between the two formats.

     There is one special section, the .MMIX.reg_contents section. Contents in
     this section is assumed to correspond to that of global registers, and
     symbols referring to it are translated to special symbols, equal to
     registers. In a final link, the start address of the .MMIX.reg_contents
     section corresponds to the first allocated global register multiplied by
     8.  Register $255 is not included in this section; it is always set to
     the program entry, which is at the symbol Main for mmo files.

     Symbols with the prefix __.MMIX.start., for example __.MMIX.start..text
     and __.MMIX.start..data are special; there must be only one each, even if
     they are local. The default linker script uses these to set the default
     start address of a section.

     Initial and trailing multiples of zero-valued 32-bit words in a section,
     are left out from an mmo file.

   ld and MSP430
     For the MSP430 it is possible to select the MPU architecture. The flag -m
     [mpu type] will select an appropriate linker script for selected MPU
     type. (To get a list of known MPUs just pass -m help option to the
     linker).

     The linker will recognize some extra sections which are MSP430 specific:

     .vectors
             Defines a portion of ROM where interrupt vectors located.

     .bootloader
             Defines the bootloader portion of the ROM (if applicable). Any
             code in this section will be uploaded to the MPU.

     .infomem
             Defines an information memory section (if applicable). Any code
             in this section will be uploaded to the MPU.

     .infomemnobits
             This is the same as the .infomem section except that any code in
             this section will not be uploaded to the MPU.

     .noinit
             Denotes a portion of RAM located above .bss section.

             The last two sections are used by gcc.

   ld(and) PowerPC 32-bit ELF Support
     Branches on PowerPC processors are limited to a signed 26-bit
     displacement, which may result in ld giving relocation truncated to fit
     errors with very large programs.  --relax enables the generation of
     trampolines that can access the entire 32-bit address space. These
     trampolines are inserted at section boundaries, so may not themselves be
     reachable if an input section exceeds 33M in size.

     --bss-plt
             Current PowerPC GCC accepts a -msecure-plt option that generates
             code capable of using a newer PLT and GOT layout that has the
             security advantage of no executable section ever needing to be
             writable and no writable section ever being executable. PowerPC
             ld will generate this layout, including stubs to access the PLT,
             if all input files (including startup and static libraries) were
             compiled with -msecure-plt.  --bss-plt forces the old BSS PLT
             (and GOT layout) which can give slightly better performance.

     --secure-plt
             ld will use the new PLT and GOT layout if it is linking new -fpic
             or -fPIC code, but does not do so automatically when linking non-
             PIC code. This option requests the new PLT and GOT layout. A
             warning will be given if some object file requires the old style
             BSS PLT.

     --sdata-got
             The new secure PLT and GOT are placed differently relative to
             other sections compared to older BSS PLT and GOT placement. The
             location of .plt must change because the new secure PLT is an
             initialized section while the old PLT is uninitialized. The
             reason for the .got change is more subtle: The new placement
             allows .got to be read-only in applications linked with -z relro
             -z now.  However, this placement means that .sdata cannot always
             be used in shared libraries, because the PowerPC ABI accesses
             .sdata in shared libraries from the GOT pointer.  --sdata-got
             forces the old GOT placement. PowerPC GCC doesn't use .sdata in
             shared libraries, so this option is really only useful for other
             compilers that may do so.

     --emit-stub-syms
             This option causes ld to label linker stubs with a local symbol
             that encodes the stub type and destination.

     --no-tls-optimize
             PowerPC ld normally performs some optimization of code sequences
             used to access Thread-Local Storage. Use this option to disable
             the optimization.

   ld(and) PowerPC64 64-bit ELF Support
     --stub-group-size
             Long branch stubs, PLT call stubs and TOC adjusting stubs are
             placed by ld in stub sections located between groups of input
             sections.  --stub-group-size specifies the maximum size of a
             group of input sections handled by one stub section. Since branch
             offsets are signed, a stub section may serve two groups of input
             sections, one group before the stub section, and one group after
             it. However, when using conditional branches that require stubs,
             it may be better (for branch prediction) that stub sections only
             serve one group of input sections. A negative value for N chooses
             this scheme, ensuring that branches to stubs always use a
             negative offset. Two special values of N are recognized, 1 and
             -1.  These both instruct ld to automatically size input section
             groups for the branch types detected, with the same behaviour
             regarding stub placement as other positive or negative values of
             N respectively.

             Note that --stub-group-size does not split input sections. A
             single input section larger than the group size specified will of
             course create a larger group (of one section). If input sections
             are too large, it may not be possible for a branch to reach its
             stub.

     --emit-stub-syms
             This option causes ld to label linker stubs with a local symbol
             that encodes the stub type and destination.

     --dotsyms, --no-dotsyms
             These two options control how ld interprets version patterns in a
             version script. Older PowerPC64 compilers emitted both a function
             descriptor symbol with the same name as the function, and a code
             entry symbol with the name prefixed by a dot ( .).  To properly
             version a function foo, the version script thus needs to control
             both foo and .foo.  The option --dotsyms, on by default,
             automatically adds the required dot-prefixed patterns. Use
             --no-dotsyms to disable this feature.

     --no-tls-optimize
             PowerPC64 ld normally performs some optimization of code
             sequences used to access Thread-Local Storage. Use this option to
             disable the optimization.

     --no-opd-optimize
             PowerPC64 ld normally removes .opd section entries corresponding
             to deleted link-once functions, or functions removed by the
             action of --gc-sections or linker scrip /DISCARD/.  Use this
             option to disable .opd optimization.

     --non-overlapping-opd
             Some PowerPC64 compilers have an option to generate compressed
             .opd entries spaced 16 bytes apart, overlapping the third word,
             the static chain pointer (unused in C) with the first word of the
             next entry. This option expands such entries to the full 24
             bytes.

     --no-toc-optimize
             PowerPC64 ld normally removes unused .toc section entries. Such
             entries are detected by examining relocations that reference the
             TOC in code sections. A reloc in a deleted code section marks a
             TOC word as unneeded, while a reloc in a kept code section marks
             a TOC word as needed.  Since the TOC may reference itself, TOC
             relocs are also examined. TOC words marked as both needed and
             unneeded will of course be kept. TOC words without any
             referencing reloc are assumed to be part of a multi-word entry,
             and are kept or discarded as per the nearest marked preceding
             word. This works reliably for compiler generated code, but may be
             incorrect if assembly code is used to insert TOC entries. Use
             this option to disable the optimization.

     --no-multi-toc
             By default, PowerPC64 GCC generates code for a TOC model where
             TOC entries are accessed with a 16-bit offset from r2. This
             limits the total TOC size to 64K. PowerPC64 ld extends this limit
             by grouping code sections such that each group uses less than 64K
             for its TOC entries, then inserts r2 adjusting stubs between
             inter-group calls.  ld does not split apart input sections, so
             cannot help if a single input file has a .toc section that
             exceeds 64K, most likely from linking multiple files with ld(-r).
             Use this option to turn off this feature.

   ld(and) SPU ELF Support
     --plugin
             This option marks an executable as a PIC plugin module.

     --no-overlays
             Normally, ld recognizes calls to functions within overlay
             regions, and redirects such calls to an overlay manager via a
             stub.  ld also provides a built-in overlay manager. This option
             turns off all this special overlay handling.

     --emit-stub-syms
             This option causes ld to label overlay stubs with a local symbol
             that encodes the stub type and destination.

     --extra-overlay-stubs
             This option causes ld to add overlay call stubs on all function
             calls out of overlay regions. Normally stubs are not added on
             calls to non-overlay regions.

     --local-store=lo:hi
             ld usually checks that a final executable for SPU fits in the
             address range 0 to 256k. This option may be used to change the
             range. Disable the check entirely with [--local-store=0:0].

     --stack-analysis
             SPU local store space is limited. Over-allocation of stack space
             unnecessarily limits space available for code and data, while
             under-allocation results in runtime failures. If given this
             option, ld will provide an estimate of maximum stack usage.  ld
             does this by examining symbols in code sections to determine the
             extents of functions, and looking at function prologues for stack
             adjusting instructions.  A call-graph is created by looking for
             relocations on branch instructions.  The graph is then searched
             for the maximum stack usage path. Note that this analysis does
             not find calls made via function pointers, and does not handle
             recursion and other cycles in the call graph. Stack usage may be
             under-estimated if your code makes such calls. Also, stack usage
             for dynamic allocation, e.g.  alloca, will not be detected. If a
             link map is requested, detailed information about each function's
             stack usage and calls will be given.

     --emit-stack-syms
             This option, if given along with [--stack-analysis] will result
             in ld emitting stack sizing symbols for each function. These take
             the form __stack_<function_name> for global functions, and
             __stack_<number>_<function_name> for static functions.  <number>
             is the section id in hex. The value of such symbols is the stack
             requirement for the corresponding function. The symbol size will
             be zero, type STT_NOTYPE, binding STB_LOCAL, and section SHN_ABS.

   ld's(Support) for Various TI COFF Versions
     The --format switch allows selection of one of the various TI COFF
     versions. The latest of this writing is 2; versions 0 and 1 are also
     supported. The TI COFF versions also vary in header byte-order format; ld
     will read any version or byte order, but the output header format depends
     on the default specified by the specific target.

   ld(and) WIN32 (cygwin/mingw)
     This section describes some of the win32 specific ld issues. See
     Options,,Command Line Options for detailed description of the command
     line options mentioned here.

     import libraries
             The standard Windows linker creates and uses so-called import
             libraries, which contains information for linking to dll's. They
             are regular static archives and are handled as any other static
             archive. The cygwin and mingw ports of ld have specific support
             for creating such libraries provided with the --out-implib
             command line option.

     exporting DLL symbols
             The cygwin/mingw ld has several ways to export symbols for dll's.

             using auto-export functionality
                     By default ld exports symbols with the auto-export
                     functionality, which is controlled by the following
                     command line options:

                     ·   --export-all-symbols [This is the default]

                     ·   --exclude-symbols

                     ·   --exclude-libs

                     If, however, --export-all-symbols is not given explicitly
                     on the command line, then the default auto-export
                     behavior will be disabled if either of the following are
                     true:

                     ·   A DEF file is used.

                     ·   Any symbol in any object file was marked with the
                         __declspec(dllexport) attribute.

             using a DEF file
                     Another way of exporting symbols is using a DEF file. A
                     DEF file is an ASCII file containing definitions of
                     symbols which should be exported when a dll is created.
                     Usually it is named <dll name>.def and is added as any
                     other object file to the linker's command line. The
                     file's name must end in .def or .DEF.

                           gcc -o <output> <objectfiles> <dll name>.def

                     Using a DEF file turns off the normal auto-export
                     behavior, unless the --export-all-symbols option is also
                     used.

                     Here is an example of a DEF file for a shared library
                     called xyz.dll:

                           LIBRARY "xyz.dll" BASE=0x20000000

                           EXPORTS
                           foo
                           bar
                           _bar = bar
                           another_foo = abc.dll.afoo
                           var1 DATA

                     This example defines a DLL with a non-default base
                     address and five symbols in the export table. The third
                     exported symbol _bar is an alias for the second. The
                     fourth symbol, another_foo is resolved by "forwarding" to
                     another module and treating it as an alias for afoo
                     exported from the DLL abc.dll.  The final symbol var1 is
                     declared to be a data object.

                     The optional LIBRARY <name> command indicates the
                     internal name of the output DLL. If <name> does not
                     include a suffix, the default library suffix, .DLL is
                     appended.

                     When the .DEF file is used to build an application,
                     rather than a library, the NAME <name> command should be
                     used instead of LIBRARY.  If <name> does not include a
                     suffix, the default executable suffix, .EXE is appended.

                     With either LIBRARY <name> or NAME <name> the optional
                     specification BASE = <number> may be used to specify a
                     non-default base address for the image.

                     If neither LIBRARY <name> nor NAME <name> is specified,
                     or they specify an empty string, the internal name is the
                     same as the filename specified on the command line.

                     The complete specification of an export symbol is:

                           EXPORTS
                             ( (  ( <name1> [ = <name2> ] )
                                | ( <name1> = <module-name> . <external-name>))
                             [ @ <integer> ] [NONAME] [DATA] [CONSTANT] [PRIVATE] ) *

                     Declares <name1> as an exported symbol from the DLL, or
                     declares <name1> as an exported alias for <name2>; or
                     declares <name1> as a "forward" alias for the symbol
                     <external-name> in the DLL <module-name>.  Optionally,
                     the symbol may be exported by the specified ordinal
                     <integer> alias.

                     The optional keywords that follow the declaration
                     indicate:

                     NONAME: Do not put the symbol name in the DLL's export
                     table. It will still be exported by its ordinal alias
                     (either the value specified by the .def specification or,
                     otherwise, the value assigned by the linker). The symbol
                     name, however, does remain visible in the import library
                     (if any), unless PRIVATE is also specified.

                     DATA: The symbol is a variable or object, rather than a
                     function. The import lib will export only an indirect
                     reference to foo as the symbol _imp__foo (ie, foo must be
                     resolved as *_imp__foo).

                     CONSTANT: Like DATA, but put the undecorated foo as well
                     as _imp__foo into the import library. Both refer to the
                     read-only import address table's pointer to the variable,
                     not to the variable itself. This can be dangerous.  If
                     the user code fails to add the dllimport attribute and
                     also fails to explicitly add the extra indirection that
                     the use of the attribute enforces, the application will
                     behave unexpectedly.

                     PRIVATE: Put the symbol in the DLL's export table, but do
                     not put it into the static import library used to resolve
                     imports at link time. The symbol can still be imported
                     using the LoadLibrary/GetProcAddress API at runtime or by
                     by using the GNU ld extension of linking directly to the
                     DLL without an import library. See ld/deffilep.y in the
                     binutils sources for the full specification of other DEF
                     file statements

                     While linking a shared dll, ld is able to create a DEF
                     file with the --output-def <file> command line option.

             Using decorations
                     Another way of marking symbols for export is to modify
                     the source code itself, so that when building the DLL
                     each symbol to be exported is declared as:

                           __declspec(dllexport) int a_variable
                           __declspec(dllexport) void a_function(int with_args)

                     All such symbols will be exported from the DLL. If,
                     however, any of the object files in the DLL contain
                     symbols decorated in this way, then the normal auto-
                     export behavior is disabled, unless the
                     --export-all-symbols option is also used.

                     Note that object files that wish to access these symbols
                     must not decorate them with dllexport. Instead, they
                     should use dllimport, instead:

                           __declspec(dllimport) int a_variable
                           __declspec(dllimport) void a_function(int with_args)

                     This complicates the structure of library header files,
                     because when included by the library itself the header
                     must declare the variables and functions as dllexport,
                     but when included by client code the header must declare
                     them as dllimport. There are a number of idioms that are
                     typically used to do this; often client code can omit the
                     __declspec() declaration completely. See
                     --enable-auto-import and automatic data imports for more
                     information.

     automatic data imports
             The standard Windows dll format supports data imports from dlls
             only by adding special decorations (dllimport/dllexport), which
             let the compiler produce specific assembler instructions to deal
             with this issue. This increases the effort necessary to port
             existing Un*x code to these platforms, especially for large c++
             libraries and applications. The auto-import feature, which was
             initially provided by Paul Sokolovsky, allows one to omit the
             decorations to achieve a behavior that conforms to that on
             POSIX/Un*x platforms. This feature is enabled with the
             --enable-auto-import command-line option, although it is enabled
             by default on cygwin/mingw. The --enable-auto-import option
             itself now serves mainly to suppress any warnings that are
             ordinarily emitted when linked objects trigger the feature's use.

             auto-import of variables does not always work flawlessly without
             additional assistance. Sometimes, you will see this message

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

             The --enable-auto-import documentation explains why this error
             occurs, and several methods that can be used to overcome this
             difficulty. One of these methods is the runtime pseudo-relocs
             feature, described below.

             For complex variables imported from DLLs (such as structs or
             classes), object files typically contain a base address for the
             variable and an offset ( addend) within the variable--to specify
             a particular field or public member, for instance.
             Unfortunately, the runtime loader used in win32 environments is
             incapable of fixing these references at runtime without the
             additional information supplied by dllimport/dllexport
             decorations. The standard auto-import feature described above is
             unable to resolve these references.

             The --enable-runtime-pseudo-relocs switch allows these references
             to be resolved without error, while leaving the task of adjusting
             the references themselves (with their non-zero addends) to
             specialized code provided by the runtime environment. Recent
             versions of the cygwin and mingw environments and compilers
             provide this runtime support; older versions do not. However, the
             support is only necessary on the developer's platform; the
             compiled result will run without error on an older system.

             --enable-runtime-pseudo-relocs is not the default; it must be
             explicitly enabled as needed.

     direct linking to a dll
             The cygwin/mingw ports of ld support the direct linking,
             including data symbols, to a dll without the usage of any import
             libraries. This is much faster and uses much less memory than
             does the traditional import library method, especially when
             linking large libraries or applications. When ld creates an
             import lib, each function or variable exported from the dll is
             stored in its own bfd, even though a single bfd could contain
             many exports.  The overhead involved in storing, loading, and
             processing so many bfd's is quite large, and explains the
             tremendous time, memory, and storage needed to link against
             particularly large or complex libraries when using import libs.

             Linking directly to a dll uses no extra command-line switches
             other than -L and -l, because ld already searches for a number of
             names to match each library. All that is needed from the
             developer's perspective is an understanding of this search, in
             order to force ld to select the dll instead of an import library.

             For instance, when ld is called with the argument -lxxx it will
             attempt to find, in the first directory of its search path,

                   libxxx.dll.a
                   xxx.dll.a
                   libxxx.a
                   xxx.lib
                   cygxxx.dll (*)
                   libxxx.dll
                   xxx.dll

             before moving on to the next directory in the search path.

             (*) Actually, this is not cygxxx.dll but in fact is
             <prefix>xxx.dll, where <prefix> is set by the ld option
             --dll-search-prefix=<prefix>.  In the case of cygwin, the
             standard gcc spec file includes --dll-search-prefix=cyg, so in
             effect we actually search for cygxxx.dll.

             Other win32-based unix environments, such as mingw or pw32, may
             use other <prefix> es, although at present only cygwin makes use
             of this feature. It was originally intended to help avoid name
             conflicts among dll's built for the various win32/un*x
             environments, so that (for example) two versions of a zlib dll
             could coexist on the same machine.

             The generic cygwin/mingw path layout uses a bin directory for
             applications and dll's and a lib directory for the import
             libraries (using cygwin nomenclature):

                   bin/
                           cygxxx.dll
                   lib/
                           libxxx.dll.a   (in case of dll's)
                           libxxx.a       (in case of static archive)

             Linking directly to a dll without using the import library can be
             done two ways:

             1. Use the dll directly by adding the bin path to the link line

                   gcc -Wl,-verbose  -o a.exe -L../bin/ -lxxx

             However, as the dll's often have version numbers appended to
             their names ( cygncurses-5.dll) this will often fail, unless one
             specifies -L../bin -lncurses-5 to include the version. Import
             libs are generally not versioned, and do not have this
             difficulty.

             2. Create a symbolic link from the dll to a file in the lib
             directory according to the above mentioned search pattern. This
             should be used to avoid unwanted changes in the tools needed for
             making the app/dll.

                   ln -s bin/cygxxx.dll lib/[cyg|lib|]xxx.dll[.a]

             Then you can link without any make environment changes.

                   gcc -Wl,-verbose  -o a.exe -L../lib/ -lxxx

             This technique also avoids the version number problems, because
             the following is perfectly legal

                   bin/
                           cygxxx-5.dll
                   lib/
                           libxxx.dll.a -> ../bin/cygxxx-5.dll

             Linking directly to a dll without using an import lib will work
             even when auto-import features are exercised, and even when
             --enable-runtime-pseudo-relocs is used.

             Given the improvements in speed and memory usage, one might
             justifiably wonder why import libraries are used at all. There
             are three reasons:

             1. Until recently, the link-directly-to-dll functionality did not
             work with auto-imported data.

             2. Sometimes it is necessary to include pure static objects
             within the import library (which otherwise contains only bfd's
             for indirection symbols that point to the exports of a dll).
             Again, the import lib for the cygwin kernel makes use of this
             ability, and it is not possible to do this without an import lib.

             3. Symbol aliases can only be resolved using an import lib. This
             is critical when linking against OS-supplied dll's (eg, the win32
             API) in which symbols are usually exported as undecorated aliases
             of their stdcall-decorated assembly names.

             So, import libs are not going away. But the ability to replace
             true import libs with a simple symbolic link to (or a copy of) a
             dll, in many cases, is a useful addition to the suite of tools
             binutils makes available to the win32 developer. Given the
             massive improvements in memory requirements during linking,
             storage requirements, and linking speed, we expect that many
             developers will soon begin to use this feature whenever possible.

     symbol aliasing

             adding additional names
                     Sometimes, it is useful to export symbols with additional
                     names. A symbol foo will be exported as foo, but it can
                     also be exported as _foo by using special directives in
                     the DEF file when creating the dll. This will affect also
                     the optional created import library. Consider the
                     following DEF file:

                           LIBRARY "xyz.dll" BASE=0x61000000

                           EXPORTS
                           foo
                           _foo = foo

                     The line _foo = foo maps the symbol foo to _foo.

                     Another method for creating a symbol alias is to create
                     it in the source code using the "weak" attribute:

                           void foo () { /* Do something.  */; }
                           void _foo () __attribute__ ((weak, alias ("foo")));

                     See the gcc manual for more information about attributes
                     and weak symbols.

             renaming symbols
                     Sometimes it is useful to rename exports. For instance,
                     the cygwin kernel does this regularly. A symbol _foo can
                     be exported as foo but not as _foo by using special
                     directives in the DEF file. (This will also affect the
                     import library, if it is created). In the following
                     example:

                           LIBRARY "xyz.dll" BASE=0x61000000

                           EXPORTS
                           _foo = foo

                     The line _foo = foo maps the exported symbol foo to _foo.

             Note: using a DEF file disables the default auto-export behavior,
             unless the --export-all-symbols command line option is used. If,
             however, you are trying to rename symbols, then you should list
             all desired exports in the DEF file, including the symbols that
             are not being renamed, and do not use the --export-all-symbols
             option. If you list only the renamed symbols in the DEF file, and
             use --export-all-symbols to handle the other symbols, then the
             both the new names and the original names for the renamed symbols
             will be exported. In effect, you'd be aliasing those symbols, not
             renaming them, which is probably not what you wanted.

     weak externals
             The Windows object format, PE, specifies a form of weak symbols
             called weak externals. When a weak symbol is linked and the
             symbol is not defined, the weak symbol becomes an alias for some
             other symbol. There are three variants of weak externals:

             ·   Definition is searched for in objects and libraries,
                 historically called lazy externals.

             ·   Definition is searched for only in other objects, not in
                 libraries.  This form is not presently implemented.

             ·   No search; the symbol is an alias. This form is not presently
                 implemented.
             As a GNU extension, weak symbols that do not specify an alternate
             symbol are supported. If the symbol is undefined when linking,
             the symbol uses a default value.

   ld and Xtensa Processors
     The default ld behavior for Xtensa processors is to interpret SECTIONS
     commands so that lists of explicitly named sections in a specification
     with a wildcard file will be interleaved when necessary to keep literal
     pools within the range of PC-relative load offsets. For example, with the
     command:

           SECTIONS
           {
             .text : {
               *(.literal .text)
             }
           }

     ld may interleave some of the .literal and .text sections from different
     object files to ensure that the literal pools are within the range of PC-
     relative load offsets. A valid interleaving might place the .literal
     sections from an initial group of files followed by the .text sections of
     that group of files. Then, the .literal sections from the rest of the
     files and the .text sections from the rest of the files would follow.

     Relaxation is enabled by default for the Xtensa version of ld and
     provides two important link-time optimizations. The first optimization is
     to combine identical literal values to reduce code size. A redundant
     literal will be removed and all the L32R instructions that use it will be
     changed to reference an identical literal, as long as the location of the
     replacement literal is within the offset range of all the L32R
     instructions. The second optimization is to remove unnecessary overhead
     from assembler-generated “longcall” sequences of L32R / CALLX n when the
     target functions are within range of direct CALL n instructions.

     For each of these cases where an indirect call sequence can be optimized
     to a direct call, the linker will change the CALLX n instruction to a
     CALL n instruction, remove the L32R instruction, and remove the literal
     referenced by the L32R instruction if it is not used for anything else.
     Removing the L32R instruction always reduces code size but can
     potentially hurt performance by changing the alignment of subsequent
     branch targets. By default, the linker will always preserve alignments,
     either by switching some instructions between 24-bit encodings and the
     equivalent density instructions or by inserting a no-op in place of the
     L32R instruction that was removed. If code size is more important than
     performance, the [--size-opt] option can be used to prevent the linker
     from widening density instructions or inserting no-ops, except in a few
     cases where no-ops are required for correctness.

     The following Xtensa-specific command-line options can be used to control
     the linker:

     --no-relax
             Since the Xtensa version of ld enables the [--relax] option by
             default, the [--no-relax] option is provided to disable
             relaxation.

     --size-opt
             When optimizing indirect calls to direct calls, optimize for code
             size more than performance. With this option, the linker will not
             insert no-ops or widen density instructions to preserve branch
             target alignment. There may still be some cases where no-ops are
             required to preserve the correctness of the code.

BFD
     The linker accesses object and archive files using the BFD libraries.
     These libraries allow the linker to use the same routines to operate on
     object files whatever the object file format. A different object file
     format can be supported simply by creating a new BFD back end and adding
     it to the library. To conserve runtime memory, however, the linker and
     associated tools are usually configured to support only a subset of the
     object file formats available. You can use objdump -i (see Section
     “objdump”) to list all the formats available for your configuration.

     As with most implementations, BFD is a compromise between several
     conflicting requirements. The major factor influencing BFD design was
     efficiency: any time used converting between formats is time which would
     not have been spent had BFD not been involved. This is partly offset by
     abstraction payback; since BFD simplifies applications and back ends,
     more time and care may be spent optimizing algorithms for a greater
     speed.

     One minor artifact of the BFD solution which you should bear in mind is
     the potential for information loss. There are two places where useful
     information can be lost using the BFD mechanism: during conversion and
     during output.See Section “BFD information loss”.

   How
     When an object file is opened, BFD subroutines automatically determine
     the format of the input object file. They then build a descriptor in
     memory with pointers to routines that will be used to access elements of
     the object file's data structures.

     As different information from the object files is required, BFD reads
     from different sections of the file and processes them. For example, a
     very common operation for the linker is processing symbol tables. Each
     BFD back end provides a routine for converting between the object file's
     representation of symbols and an internal canonical format. When the
     linker asks for the symbol table of an object file, it calls through a
     memory pointer to the routine from the relevant BFD back end which reads
     and converts the table into a canonical form. The linker then operates
     upon the canonical form. When the link is finished and the linker writes
     the output file's symbol table, another BFD back end routine is called to
     take the newly created symbol table and convert it into the chosen output
     format.

     Works: Outline of BFD

     Information can be lost during output. The output formats supported by
     BFD do not provide identical facilities, and information which can be
     described in one form has nowhere to go in another format. One example of
     this is alignment information in b.out.  There is nowhere in an a.out
     format file to store alignment information on the contained data, so when
     a file is linked from b.out and an a.out image is produced, alignment
     information will not propagate to the output file. (The linker will still
     use the alignment information internally, so the link is performed
     correctly).

     Another example is COFF section names. COFF files may contain an
     unlimited number of sections, each one with a textual section name. If
     the target of the link is a format which does not have many sections
     (e.g., a.out) or has sections without names (e.g., the Oasys format), the
     link cannot be done simply. You can circumvent this problem by describing
     the desired input-to-output section mapping with the linker command
     language.

     Information can be lost during canonicalization. The BFD internal
     canonical form of the external formats is not exhaustive; there are
     structures in input formats for which there is no direct representation
     internally. This means that the BFD back ends cannot maintain all
     possible data richness through the transformation between external to
     internal and back to external formats.

     This limitation is only a problem when an application reads one format
     and writes another. Each BFD back end is responsible for maintaining as
     much data as possible, and the internal BFD canonical form has structures
     which are opaque to the BFD core, and exported only to the back ends.
     When a file is read in one format, the canonical form is generated for
     BFD and the application.  At the same time, the back end saves away any
     information which may otherwise be lost. If the data is then written back
     in the same format, the back end routine will be able to use the
     canonical form provided by the BFD core as well as the information it
     prepared earlier. Since there is a great deal of commonality between back
     ends, there is no information lost when linking or copying big endian
     COFF to little endian COFF, or a.out to b.out.  When a mixture of formats
     is linked, the information is only lost from the files whose format
     differs from the destination.

     The BFD canonical object-file format

     The greatest potential for loss of information occurs when there is the
     least overlap between the information provided by the source format, that
     stored by the canonical format, and that needed by the destination
     format. A brief description of the canonical form may help you understand
     which kinds of data you can count on preserving across conversions.

     files   Information stored on a per-file basis includes target machine
             architecture, particular implementation format type, a demand
             pageable bit, and a write protected bit. Information like Unix
             magic numbers is not stored here---only the magic numbers'
             meaning, so a ZMAGIC file would have both the demand pageable bit
             and the write protected text bit set. The byte order of the
             target is stored on a per-file basis, so that big- and little-
             endian object files may be used with one another.

     sections
             Each section in the input file contains the name of the section,
             the section's original address in the object file, size and
             alignment information, various flags, and pointers into other BFD
             data structures.

     symbols
             Each symbol contains a pointer to the information for the object
             file which originally defined it, its name, its value, and
             various flag bits. When a BFD back end reads in a symbol table,
             it relocates all symbols to make them relative to the base of the
             section where they were defined. Doing this ensures that each
             symbol points to its containing section. Each symbol also has a
             varying amount of hidden private data for the BFD back end. Since
             the symbol points to the original file, the private data format
             for that symbol is accessible.  ld can operate on a collection of
             symbols of wildly different formats without problems.

             Normal global and simple local symbols are maintained on output,
             so an output file (no matter its format) will retain symbols
             pointing to functions and to global, static, and common
             variables. Some symbol information is not worth retaining; in
             a.out, type information is stored in the symbol table as long
             symbol names. This information would be useless to most COFF
             debuggers; the linker has command line switches to allow users to
             throw it away.

             There is one word of type information within the symbol, so if
             the format supports symbol type information within symbols (for
             example, COFF, IEEE, Oasys) and the type is simple enough to fit
             within one word (nearly everything but aggregates), the
             information will be preserved.

     relocation level
             Each canonical BFD relocation record contains a pointer to the
             symbol to relocate to, the offset of the data to relocate, the
             section the data is in, and a pointer to a relocation type
             descriptor. Relocation is performed by passing messages through
             the relocation type descriptor and the symbol pointer. Therefore,
             relocations can be performed on output data using a relocation
             method that is only available in one of the input formats. For
             instance, Oasys provides a byte relocation format. A relocation
             record requesting this relocation type would point indirectly to
             a routine to perform this, so the relocation may be performed on
             a byte being written to a 68k COFF file, even though 68k COFF has
             no such relocation type.

     line numbers
             Object formats can contain, for debugging purposes, some form of
             mapping between symbols, source line numbers, and addresses in
             the output file. These addresses have to be relocated along with
             the symbol information. Each symbol with an associated list of
             line number records points to the first record of the list.  The
             head of a line number list consists of a pointer to the symbol,
             which allows finding out the address of the function whose line
             number is being described. The rest of the list is made up of
             pairs: offsets into the section and line numbers. Any format
             which can simply derive this information can pass it successfully
             between formats (COFF, IEEE and Oasys).

Reporting Bugs
     Your bug reports play an essential role in making ld reliable.

     Reporting a bug may help you by bringing a solution to your problem, or
     it may not. But in any case the principal function of a bug report is to
     help the entire community by making the next version of ld work better.
     Bug reports are your contribution to the maintenance of ld.

     In order for a bug report to serve its purpose, you must include the
     information that enables us to fix the bug.

   Have You Found a Bug?
     If you are not sure whether you have found a bug, here are some
     guidelines:

     ·   If the linker gets a fatal signal, for any input whatever, that is a
         ld bug. Reliable linkers never crash.

     ·   If ld produces an error message for valid input, that is a bug.

     ·   If ld does not produce an error message for invalid input, that may
         be a bug. In the general case, the linker can not verify that object
         files are correct.

     ·   If you are an experienced user of linkers, your suggestions for
         improvement of ld are welcome in any case.

   How to Report Bugs
     A number of companies and individuals offer support for GNU products. If
     you obtained ld from a support organization, we recommend you contact
     that organization first.

     You can find contact information for many support companies and
     individuals in the file etc/SERVICE in the GNU Emacs distribution.

     The fundamental principle of reporting bugs usefully is this: report all
     the facts.  If you are not sure whether to state a fact or leave it out,
     state it!

     Often people omit facts because they think they know what causes the
     problem and assume that some details do not matter. Thus, you might
     assume that the name of a symbol you use in an example does not matter.
     Well, probably it does not, but one cannot be sure. Perhaps the bug is a
     stray memory reference which happens to fetch from the location where
     that name is stored in memory; perhaps, if the name were different, the
     contents of that location would fool the linker into doing the right
     thing despite the bug. Play it safe and give a specific, complete
     example. That is the easiest thing for you to do, and the most helpful.

     Keep in mind that the purpose of a bug report is to enable us to fix the
     bug if it is new to us. Therefore, always write your bug reports on the
     assumption that the bug has not been reported previously.

     Sometimes people give a few sketchy facts and ask, “Does this ring a
     bell?”  This cannot help us fix a bug, so it is basically useless. We
     respond by asking for enough details to enable us to investigate. You
     might as well expedite matters by sending them to begin with.

     To enable us to fix the bug, you should include all these things:

     ·   The version of ld.  ld announces it if you start it with the
         --version argument.

         Without this, we will not know whether there is any point in looking
         for the bug in the current version of ld.

     ·   Any patches you may have applied to the ld source, including any
         patches made to the BFD library.

     ·   The type of machine you are using, and the operating system name and
         version number.

     ·   What compiler (and its version) was used to compile ld ---e.g. “
         gcc-2.7 ”.

     ·   The command arguments you gave the linker to link your example and
         observe the bug. To guarantee you will not omit something important,
         list them all.  A copy of the Makefile (or the output from make) is
         sufficient.

         If we were to try to guess the arguments, we would probably guess
         wrong and then we might not encounter the bug.

     ·   A complete input file, or set of input files, that will reproduce the
         bug.  It is generally most helpful to send the actual object files
         provided that they are reasonably small. Say no more than 10K. For
         bigger files you can either make them available by FTP or HTTP or
         else state that you are willing to send the object file(s) to
         whomever requests them. (Note - your email will be going to a mailing
         list, so we do not want to clog it up with large attachments).  But
         small attachments are best.

         If the source files were assembled using gas or compiled using gcc,
         then it may be OK to send the source files rather than the object
         files. In this case, be sure to say exactly what version of gas or
         gcc was used to produce the object files. Also say how gas or gcc
         were configured.

     ·   A description of what behavior you observe that you believe is
         incorrect.  For example, “It gets a fatal signal.”

         Of course, if the bug is that ld gets a fatal signal, then we will
         certainly notice it. But if the bug is incorrect output, we might not
         notice unless it is glaringly wrong. You might as well not give us a
         chance to make a mistake.

         Even if the problem you experience is a fatal signal, you should
         still say so explicitly. Suppose something strange is going on, such
         as, your copy of ld is out of sync, or you have encountered a bug in
         the C library on your system.  (This has happened!) Your copy might
         crash and ours would not. If you told us to expect a crash, then when
         ours fails to crash, we would know that the bug was not happening for
         us. If you had not told us to expect a crash, then we would not be
         able to draw any conclusion from our observations.

     ·   If you wish to suggest changes to the ld source, send us context
         diffs, as generated by diff with the -u, -c, or -p option. Always
         send diffs from the old file to the new file. If you even discuss
         something in the ld source, refer to it by context, not by line
         number.

         The line numbers in our development sources will not match those in
         your sources.  Your line numbers would convey no useful information
         to us.

     Here are some things that are not necessary:

     ·   A description of the envelope of the bug.

         Often people who encounter a bug spend a lot of time investigating
         which changes to the input file will make the bug go away and which
         changes will not affect it.

         This is often time consuming and not very useful, because the way we
         will find the bug is by running a single example under the debugger
         with breakpoints, not by pure deduction from a series of examples. We
         recommend that you save your time for something else.

         Of course, if you can find a simpler example to report instead of the
         original one, that is a convenience for us. Errors in the output will
         be easier to spot, running under the debugger will take less time,
         and so on.

         However, simplification is not vital; if you do not want to do this,
         report the bug anyway and send us the entire test case you used.

     ·   A patch for the bug.

         A patch for the bug does help us if it is a good one. But do not omit
         the necessary information, such as the test case, on the assumption
         that a patch is all we need. We might see problems with your patch
         and decide to fix the problem another way, or we might not understand
         it at all.

         Sometimes with a program as complicated as ld it is very hard to
         construct an example that will make the program follow a certain path
         through the code. If you do not send us the example, we will not be
         able to construct one, so we will not be able to verify that the bug
         is fixed.

         And if we cannot understand what bug you are trying to fix, or why
         your patch should be an improvement, we will not install it. A test
         case will help us to understand.

     ·   A guess about what the bug is or what it depends on.

         Such guesses are usually wrong. Even we cannot guess right about such
         things without first using the debugger to find the facts.

MRI Compatible Script Files
     To aid users making the transition to GNU ld from the MRI linker, ld can
     use MRI compatible linker scripts as an alternative to the more general-
     purpose linker scripting language described in Scripts. MRI compatible
     linker scripts have a much simpler command set than the scripting
     language otherwise used with ld.  GNU ld supports the most commonly used
     MRI linker commands; these commands are described here.

     In general, MRI scripts aren't of much use with the a.out object file
     format, since it only has three sections and MRI scripts lack some
     features to make use of them.

     You can specify a file containing an MRI-compatible script using the -c
     command-line option.

     Each command in an MRI-compatible script occupies its own line; each
     command line starts with the keyword that identifies the command (though
     blank lines are also allowed for punctuation). If a line of an MRI-
     compatible script begins with an unrecognized keyword, ld issues a
     warning message, but continues processing the script.

     Lines beginning with * are comments.

     You can write these commands using all upper-case letters, or all lower
     case; for example, chip is the same as CHIP.  The following list shows
     only the upper-case form of each command.

     ABSOLUTE secname

     ABSOLUTE secname, secname, ... secname
             Normally, ld includes in the output file all sections from all
             the input files. However, in an MRI-compatible script, you can
             use the ABSOLUTE command to restrict the sections that will be
             present in your output program.  If the ABSOLUTE command is used
             at all in a script, then only the sections named explicitly in
             ABSOLUTE commands will appear in the linker output. You can still
             use other input sections (whatever you select on the command
             line, or using LOAD) to resolve addresses in the output file.

     ALIAS out-secname, in-secname
             Use this command to place the data from input section in-secname
             in a section called out-secname in the linker output file.

             in-secname may be an integer.

     ALIGN secname = expression
             Align the section called secname to expression.  The expression
             should be a power of two.

     BASE expression
             Use the value of expression as the lowest address (other than
             absolute addresses) in the output file.

     CHIP expression

     CHIP expression, expression
             This command does nothing; it is accepted only for compatibility.

     END     This command does nothing whatever; it's only accepted for
             compatibility.

     FORMAT output-format
             Similar to the OUTPUT_FORMAT command in the more general linker
             language, but restricted to one of these output formats:

             1.   S-records, if output-format is S

             2.   IEEE, if output-format is IEEE

             3.   COFF (the coff-m68k variant in BFD), if output-format is
                  COFF

     LIST anything...
             Print (to the standard output file) a link map, as produced by
             the ld command-line option -M.

             The keyword LIST may be followed by anything on the same line,
             with no change in its effect.

     LOAD filename

     LOAD filename, filename, ... filename
             Include one or more object file filename in the link; this has
             the same effect as specifying filename directly on the ld command
             line.

     NAME output-name
             output-name is the name for the program produced by ld; the MRI-
             compatible command NAME is equivalent to the command-line option
             -o or the general script language command OUTPUT.

     ORDER secname, secname, ... secname

     ORDER secname secname secname
             Normally, ld orders the sections in its output file in the order
             in which they first appear in the input files. In an MRI-
             compatible script, you can override this ordering with the ORDER
             command. The sections you list with ORDER will appear first in
             your output file, in the order specified.

     PUBLIC name= expression

     PUBLIC name, expression

     PUBLIC name expression
             Supply a value ( expression) for external symbol name used in the
             linker input files.

     SECT secname, expression

     SECT secname= expression

     SECT secname expression
             You can use any of these three forms of the SECT command to
             specify the start address ( expression) for section secname.  If
             you have more than one SECT statement for the same secname, only
             the first sets the start address.

GNU Free Documentation License
           Copyright (C) 2000, 2003 Free Software Foundation, Inc. 51 Franklin
           Street, Fifth Floor, Boston, MA 02110-1301 USA

           Everyone is permitted to copy and distribute verbatim copies of
           this license document, but changing it is not allowed.

     1.   PREAMBLE

          The purpose of this License is to make a manual, textbook, or other
          written document “free” in the sense of freedom: to assure everyone
          the effective freedom to copy and redistribute it, with or without
          modifying it, either commercially or noncommercially. Secondarily,
          this License preserves for the author and publisher a way to get
          credit for their work, while not being considered responsible for
          modifications made by others.

          This License is a kind of “copyleft”, which means that derivative
          works of the document must themselves be free in the same sense. It
          complements the GNU General Public License, which is a copyleft
          license designed for free software.

          We have designed this License in order to use it for manuals for
          free software, because free software needs free documentation: a
          free program should come with manuals providing the same freedoms
          that the software does. But this License is not limited to software
          manuals; it can be used for any textual work, regardless of subject
          matter or whether it is published as a printed book. We recommend
          this License principally for works whose purpose is instruction or
          reference.

     2.   APPLICABILITY AND DEFINITIONS

          This License applies to any manual or other work that contains a
          notice placed by the copyright holder saying it can be distributed
          under the terms of this License. The “Document”, below, refers to
          any such manual or work. Any member of the public is a licensee, and
          is addressed as “you.”

          A “Modified Version” of the Document means any work containing the
          Document or a portion of it, either copied verbatim, or with
          modifications and/or translated into another language.

          A “Secondary Section” is a named appendix or a front-matter section
          of the Document that deals exclusively with the relationship of the
          publishers or authors of the Document to the Document's overall
          subject (or to related matters) and contains nothing that could fall
          directly within that overall subject.  (For example, if the Document
          is in part a textbook of mathematics, a Secondary Section may not
          explain any mathematics.) The relationship could be a matter of
          historical connection with the subject or with related matters, or
          of legal, commercial, philosophical, ethical or political position
          regarding them.

          The “Invariant Sections” are certain Secondary Sections whose titles
          are designated, as being those of Invariant Sections, in the notice
          that says that the Document is released under this License.

          The “Cover Texts” are certain short passages of text that are
          listed, as Front-Cover Texts or Back-Cover Texts, in the notice that
          says that the Document is released under this License.

          A “Transparent” copy of the Document means a machine-readable copy,
          represented in a format whose specification is available to the
          general public, whose contents can be viewed and edited directly and
          straightforwardly with generic text editors or (for images composed
          of pixels) generic paint programs or (for drawings) some widely
          available drawing editor, and that is suitable for input to text
          formatters or for automatic translation to a variety of formats
          suitable for input to text formatters. A copy made in an otherwise
          Transparent file format whose markup has been designed to thwart or
          discourage subsequent modification by readers is not Transparent. A
          copy that is not “Transparent” is called “Opaque.”

          Examples of suitable formats for Transparent copies include plain
          ASCII without markup, Texinfo input format, LaTeX input format, SGML
          or XML using a publicly available DTD, and standard-conforming
          simple HTML designed for human modification.  Opaque formats include
          PostScript, PDF, proprietary formats that can be read and edited
          only by proprietary word processors, SGML or XML for which the DTD
          and/or processing tools are not generally available, and the
          machine-generated HTML produced by some word processors for output
          purposes only.

          The “Title Page” means, for a printed book, the title page itself,
          plus such following pages as are needed to hold, legibly, the
          material this License requires to appear in the title page. For
          works in formats which do not have any title page as such, “Title
          Page” means the text near the most prominent appearance of the
          work's title, preceding the beginning of the body of the text.

     3.   VERBATIM COPYING

          You may copy and distribute the Document in any medium, either
          commercially or noncommercially, provided that this License, the
          copyright notices, and the license notice saying this License
          applies to the Document are reproduced in all copies, and that you
          add no other conditions whatsoever to those of this License. You may
          not use technical measures to obstruct or control the reading or
          further copying of the copies you make or distribute. However, you
          may accept compensation in exchange for copies. If you distribute a
          large enough number of copies you must also follow the conditions in
          section 3.

          You may also lend copies, under the same conditions stated above,
          and you may publicly display copies.

     4.   COPYING IN QUANTITY

          If you publish printed copies of the Document numbering more than
          100, and the Document's license notice requires Cover Texts, you
          must enclose the copies in covers that carry, clearly and legibly,
          all these Cover Texts: Front-Cover Texts on the front cover, and
          Back-Cover Texts on the back cover. Both covers must also clearly
          and legibly identify you as the publisher of these copies.  The
          front cover must present the full title with all words of the title
          equally prominent and visible. You may add other material on the
          covers in addition.  Copying with changes limited to the covers, as
          long as they preserve the title of the Document and satisfy these
          conditions, can be treated as verbatim copying in other respects.

          If the required texts for either cover are too voluminous to fit
          legibly, you should put the first ones listed (as many as fit
          reasonably) on the actual cover, and continue the rest onto adjacent
          pages.

          If you publish or distribute Opaque copies of the Document numbering
          more than 100, you must either include a machine-readable
          Transparent copy along with each Opaque copy, or state in or with
          each Opaque copy a publicly-accessible computer-network location
          containing a complete Transparent copy of the Document, free of
          added material, which the general network-using public has access to
          download anonymously at no charge using public-standard network
          protocols.  If you use the latter option, you must take reasonably
          prudent steps, when you begin distribution of Opaque copies in
          quantity, to ensure that this Transparent copy will remain thus
          accessible at the stated location until at least one year after the
          last time you distribute an Opaque copy (directly or through your
          agents or retailers) of that edition to the public.

          It is requested, but not required, that you contact the authors of
          the Document well before redistributing any large number of copies,
          to give them a chance to provide you with an updated version of the
          Document.

     5.   MODIFICATIONS

          You may copy and distribute a Modified Version of the Document under
          the conditions of sections 2 and 3 above, provided that you release
          the Modified Version under precisely this License, with the Modified
          Version filling the role of the Document, thus licensing
          distribution and modification of the Modified Version to whoever
          possesses a copy of it. In addition, you must do these things in the
          Modified Version:

          A. Use in the Title Page (and on the covers, if any) a title
          distinct from that of the Document, and from those of previous
          versions (which should, if there were any, be listed in the History
          section of the Document). You may use the same title as a previous
          version if the original publisher of that version gives permission.
          B. List on the Title Page, as authors, one or more persons or
          entities responsible for authorship of the modifications in the
          Modified Version, together with at least five of the principal
          authors of the Document (all of its principal authors, if it has
          less than five).  C.  State on the Title page the name of the
          publisher of the Modified Version, as the publisher.  D. Preserve
          all the copyright notices of the Document.  E. Add an appropriate
          copyright notice for your modifications adjacent to the other
          copyright notices.  F. Include, immediately after the copyright
          notices, a license notice giving the public permission to use the
          Modified Version under the terms of this License, in the form shown
          in the Addendum below.  G. Preserve in that license notice the full
          lists of Invariant Sections and required Cover Texts given in the
          Document's license notice.  H. Include an unaltered copy of this
          License.  I. Preserve the section entitled “History”, and its title,
          and add to it an item stating at least the title, year, new authors,
          and publisher of the Modified Version as given on the Title Page.
          If there is no section entitled “History” in the Document, create
          one stating the title, year, authors, and publisher of the Document
          as given on its Title Page, then add an item describing the Modified
          Version as stated in the previous sentence.  J. Preserve the network
          location, if any, given in the Document for public access to a
          Transparent copy of the Document, and likewise the network locations
          given in the Document for previous versions it was based on. These
          may be placed in the “History” section. You may omit a network
          location for a work that was published at least four years before
          the Document itself, or if the original publisher of the version it
          refers to gives permission.  K. In any section entitled
          “Acknowledgements” or “Dedications”, preserve the section's title,
          and preserve in the section all the substance and tone of each of
          the contributor acknowledgements and/or dedications given therein.
          L. Preserve all the Invariant Sections of the Document, unaltered in
          their text and in their titles. Section numbers or the equivalent
          are not considered part of the section titles.  M. Delete any
          section entitled “Endorsements.” Such a section may not be included
          in the Modified Version.  N. Do not retitle any existing section as
          “Endorsements” or to conflict in title with any Invariant Section.

          If the Modified Version includes new front-matter sections or
          appendices that qualify as Secondary Sections and contain no
          material copied from the Document, you may at your option designate
          some or all of these sections as invariant.  To do this, add their
          titles to the list of Invariant Sections in the Modified Version's
          license notice. These titles must be distinct from any other section
          titles.

          You may add a section entitled “Endorsements”, provided it contains
          nothing but endorsements of your Modified Version by various
          parties--for example, statements of peer review or that the text has
          been approved by an organization as the authoritative definition of
          a standard.

          You may add a passage of up to five words as a Front-Cover Text, and
          a passage of up to 25 words as a Back-Cover Text, to the end of the
          list of Cover Texts in the Modified Version. Only one passage of
          Front-Cover Text and one of Back-Cover Text may be added by (or
          through arrangements made by) any one entity. If the Document
          already includes a cover text for the same cover, previously added
          by you or by arrangement made by the same entity you are acting on
          behalf of, you may not add another; but you may replace the old one,
          on explicit permission from the previous publisher that added the
          old one.

          The author(s) and publisher(s) of the Document do not by this
          License give permission to use their names for publicity for or to
          assert or imply endorsement of any Modified Version.

     6.   COMBINING DOCUMENTS

          You may combine the Document with other documents released under
          this License, under the terms defined in section 4 above for
          modified versions, provided that you include in the combination all
          of the Invariant Sections of all of the original documents,
          unmodified, and list them all as Invariant Sections of your combined
          work in its license notice.

          The combined work need only contain one copy of this License, and
          multiple identical Invariant Sections may be replaced with a single
          copy. If there are multiple Invariant Sections with the same name
          but different contents, make the title of each such section unique
          by adding at the end of it, in parentheses, the name of the original
          author or publisher of that section if known, or else a unique
          number. Make the same adjustment to the section titles in the list
          of Invariant Sections in the license notice of the combined work.

          In the combination, you must combine any sections entitled “History”
          in the various original documents, forming one section entitled
          “History”; likewise combine any sections entitled
          “Acknowledgements”, and any sections entitled “Dedications.” You
          must delete all sections entitled “Endorsements.”

     7.   COLLECTIONS OF DOCUMENTS

          You may make a collection consisting of the Document and other
          documents released under this License, and replace the individual
          copies of this License in the various documents with a single copy
          that is included in the collection, provided that you follow the
          rules of this License for verbatim copying of each of the documents
          in all other respects.

          You may extract a single document from such a collection, and
          distribute it individually under this License, provided you insert a
          copy of this License into the extracted document, and follow this
          License in all other respects regarding verbatim copying of that
          document.

     8.   AGGREGATION WITH INDEPENDENT WORKS

          A compilation of the Document or its derivatives with other separate
          and independent documents or works, in or on a volume of a storage
          or distribution medium, does not as a whole count as a Modified
          Version of the Document, provided no compilation copyright is
          claimed for the compilation. Such a compilation is called an
          “aggregate”, and this License does not apply to the other self-
          contained works thus compiled with the Document, on account of their
          being thus compiled, if they are not themselves derivative works of
          the Document.

          If the Cover Text requirement of section 3 is applicable to these
          copies of the Document, then if the Document is less than one
          quarter of the entire aggregate, the Document's Cover Texts may be
          placed on covers that surround only the Document within the
          aggregate. Otherwise they must appear on covers around the whole
          aggregate.

     9.   TRANSLATION

          Translation is considered a kind of modification, so you may
          distribute translations of the Document under the terms of section
          4. Replacing Invariant Sections with translations requires special
          permission from their copyright holders, but you may include
          translations of some or all Invariant Sections in addition to the
          original versions of these Invariant Sections. You may include a
          translation of this License provided that you also include the
          original English version of this License. In case of a disagreement
          between the translation and the original English version of this
          License, the original English version will prevail.

     10.  TERMINATION

          You may not copy, modify, sublicense, or distribute the Document
          except as expressly provided for under this License. Any other
          attempt to copy, modify, sublicense or distribute the Document is
          void, and will automatically terminate your rights under this
          License. However, parties who have received copies, or rights, from
          you under this License will not have their licenses terminated so
          long as such parties remain in full compliance.

     11.  FUTURE REVISIONS OF THIS LICENSE

          The Free Software Foundation may publish new, revised versions of
          the GNU Free Documentation License from time to time. Such new
          versions will be similar in spirit to the present version, but may
          differ in detail to address new problems or concerns. See
          http://www.gnu.org/copyleft/.

          Each version of the License is given a distinguishing version
          number. If the Document specifies that a particular numbered version
          of this License “or any later version” applies to it, you have the
          option of following the terms and conditions either of that
          specified version or of any later version that has been published
          (not as a draft) by the Free Software Foundation. If the Document
          does not specify a version number of this License, you may choose
          any version ever published (not as a draft) by the Free Software
          Foundation.

   ADDENDUM: How to use this License for your documents
     To use this License in a document you have written, include a copy of the
     License in the document and put the following copyright and license
     notices just after the title page:

           Copyright (C)  year  your name.
           Permission is granted to copy, distribute and/or modify this document
           under the terms of the GNU Free Documentation License, Version 1.1
           or any later version published by the Free Software Foundation;
           with the Invariant Sections being list their titles, with the
           Front-Cover Texts being list, and with the Back-Cover Texts being list.
           A copy of the license is included in the section entitled "GNU
           Free Documentation License."


     If you have no Invariant Sections, write “with no Invariant Sections”
     instead of saying which ones are invariant. If you have no Front-Cover
     Texts, write “no Front-Cover Texts” instead of “Front-Cover Texts being
     list ”; likewise for Back-Cover Texts.

     If your document contains nontrivial examples of program code, we
     recommend releasing these examples in parallel under your choice of free
     software license, such as the GNU General Public License, to permit their
     use in free software.

LD Index
                               December 10, 2019