@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.
| --audit AUDITLIB
Meaningful onELF platforms supporting the rtld-audit interface.
Adds AUDITLIB to the DT_AUDIT entry of the dynamic section. it is not checked for existence
nor will it use the DT_SONAME specified in the library.
If multiple occurances will contain a colon separated list of audit interfaces . If an object with an audit entry is found
while searching for shared libraries, the corresponding DT_DEPAUDIT entry is added to the output file.
| -b input-format
--format=input-format
If configured to support more than one kind of object file
input-format specifies a text string of the format
for files that follow on the command line.
A list of the available binary formats supported by the BFD libraries is output with objdump -i .)
You may want to use this option if you are linking files with an unusual binary format. You can also use -b to switch formats explicitly (when linking object files of different formats), by including -b input-format before each group of object files in a particular format.
The default format is taken from the environment variable "GNUTARGET".
You can also define the input format from a script, using the command "TARGET";
| -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.
| --depaudit AUDITLIB
-P AUDITLIB
Adds AUDITLIB to the "DT_DEPAUDIT" entry of the dynamic section. AUDITLIB is not checked for existence, nor will it use the DT_SONAME specified in the library. If specified multiple times "DT_DEPAUDIT" will contain a colon separated list of audit interfaces to use. This option is only meaningful onELF platforms supporting the rtld-audit interface. The -P option is provided for Solaris compatibility.
| -e entry
--entry=entry
Use entry as the explicit symbol for beginning execution of your program, rather than the default entry point. If there is no symbol named entry, the linker will try to parse entry as a number, and use that as the entry address (the number will be interpreted in base 10; you may use a leading 0x for base 16, or a leading 0 for base 8).
| --exclude-libs lib,lib,...
Specifies a list of archive libraries from which symbols should not be automatically exported. The library names may be delimited by commas or colons. Specifying "--exclude-libs ALL" excludes symbols in all archive libraries from automatic export. This option is available only for the i386 PE targeted port of the linker and forELF targeted ports. For i386 PE , symbols explicitly listed in a .def file are still exported, regardless of this option. For ELF targeted ports, symbols affected by this option will be treated as hidden.
| --exclude-modules-for-implib module,module,...
Specifies a list of object files or archive members, from which symbols should not be automatically exported, but which should be copied wholesale into the import library being generated during the link. The module names may be delimited by commas or colons, and must match exactly the filenames used by ld to open the files; for archive members, this is simply the member name, but for object files the name listed must include and match precisely any path used to specify the input file on the linker's command-line. This option is available only for the i386 PE targeted port of the linker. Symbols explicitly listed in a .def file are still exported, regardless of this option.
| -E
--export-dynamic
--no-export-dynamic
When creating a dynamically linked executable, using the -E option or the --export-dynamic option causes the linker to add all symbols to the dynamic symbol table. The dynamic symbol table is the set of symbols which are visible from dynamic objects at run time.
If you do not use either of these options (or use the --no-export-dynamic option to restore the default behavior), the dynamic symbol table will normally contain only those symbols which are referenced by some dynamic object mentioned in the link.
If you use "dlopen" to load a dynamic object which needs to refer back to the symbols defined by the program, rather than some other dynamic object, then you will probably need to use this option when linking the program itself.
You can also use the dynamic list to control what symbols should be added to the dynamic symbol table if the output format supports it. See the description of --dynamic-list.
Note that this option is specific toELF targeted ports. PE targets support a similar function to export all symbols from a DLL or EXE ; see the description of --export-all-symbols below.
| -f name
--auxiliary=name
When creating anELF 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 anELF 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 anELF shared object.
| -fini=name
When creating anELF 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.
| -soname=name
When creating anELF 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 anELF executable or shared object, call NAME when the executable or shared object is loaded, by setting DT_INIT to the address of the function. By default, the linker uses "_init" as the function to call.
| -l namespec
--library=namespec
Add the archive or object file specified by namespec to the list of files to link. This option may be used any number of times. If namespec is of the form :filename, ld will search the library path for a file called filename, otherwise it will search the library path for a file called libnamespec.a.
On systems which support shared libraries, ld may also search for files other than libnamespec.a. Specifically, onELF and SunOS systems, ld will search a directory for a library called libnamespec.so before searching for one called libnamespec.a. (By convention, a ".so" extension indicates a shared library.) Note that this behavior does not apply to :filename, which always specifies a file called filename.
The linker will search an archive only once, at the location where it is specified on the command line. If the archive defines a symbol which was undefined in some object which appeared before the archive on the command line, the linker will include the appropriate file(s) from the archive. However, an undefined symbol in an object appearing later on the command line will not cause the linker to search the archive again.
See the -( option for a way to force the linker to search archives multiple times.
You may list the same archive multiple times on the command line.
This type of archive searching is standard for Unix linkers. However, if you are using ld on AIX , note that it is different from the behaviour of the AIX linker.
| -L searchdir
--library-path=searchdir
Add path searchdir to the list of paths that ld will search for archive libraries and ld control scripts. You may use this option any number of times. The directories are searched in the order in which they are specified on the command line. Directories specified on the command line are searched before the default directories. All -L options apply to all -l options, regardless of the order in which the options appear. -L options do not affect how ld searches for a linker script unless -T option is specified.
If searchdir begins with "=", then the "=" will be replaced by the sysroot prefix, a path specified when the linker is configured.
The default set of paths searched (without being specified with -L) depends on which emulation mode ld is using, and in some cases also on how it was configured.
The paths can also be specified in a link script with the "SEARCH_DIR" command. Directories specified this way are searched at the point in which the linker script appears in the command line.
| -M
--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.
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. 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.
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".
A writable text section is allowed for PE-COFF targets, does not conform to the format specification published by Microsoft.
| --no-omagic
Negates most of the effects of the -N option. It sets the text section to be read-only, and forces the data segment to be page-aligned. Note - this option does not enable linking against shared libraries. Use -Bdynamic for this.
| -o output --output=output
Use output as the name for the program produced by ld; if this option is not specified, the name a.out is used by default. The script command "OUTPUT" can also specify the output file name.
| -O level
If level is a numeric values greater than zero ld optimizes the output. This might take significantly longer and therefore probably should only be enabled for the final binary. At the moment this option only affectsELF shared library generation. Future releases of the linker may make more use of this option. Also currently there is no difference in the linker's behaviour for different non-zero values of this option. Again this may change with future releases.
| -q
--emit-relocs
Leave relocation sections and contents in fully linked executables. Post link analysis and optimization tools may need this information in order to perform correct modifications of executables. This results in larger executables.
This option is currently only supported onELF 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 otherELF linkers, if the -R option is followed by a directory name, rather than a file name, it is treated as the -rpath option.
| -s
--strip-all
Omit all symbol information from the output file.
| -S
--strip-debug
Omit debugger symbol information (but not all symbols) from the output file.
| -t
--trace
Print the names of the input files as ld processes them.
| -T scriptfile
--script=scriptfile
Use scriptfile as the linker script. This script replaces ld's default linker script (rather than adding to it), so commandfile must specify everything necessary to describe the output file. If scriptfile does not exist in the current directory, "ld" looks for it in the directories specified by any preceding -L options. Multiple -T options accumulate.
| -dT scriptfile
--default-script=scriptfile
Use scriptfile as the default linker script.
This option is similar to the --script option except that processing of the script is delayed until after the rest of the command line has been processed. This allows options placed after the --default-script option on the command line to affect the behaviour of the linker script, which can be important when the linker command line cannot be directly controlled by the user. (eg because the command line is being constructed by another tool, such as gcc).
| -u symbol
--undefined=symbol
Force symbol to be entered in the output file as an undefined symbol. Doing this may, for example, trigger linking of additional modules from standard libraries. -u may be repeated with different option arguments to enter additional undefined symbols. This option is equivalent to the "EXTERN" linker script command.
| -Ur
For anything other than C ++ programs, this option is equivalent to -r: it generates relocatable output---i.e., an output file that can in turn serve as input to ld. When linking C ++ programs, -Ur does resolve references to constructors, unlike -r. It does not work to use -Ur on files that were themselves linked with -Ur; once the constructor table has been built, it cannot be added to. Use -Ur only for the last partial link, and -r for the others.
| --unique[= SECTION ]
Creates a separate output section for every input section matching SECTION , or if the optional wildcard SECTION argument is missing, for every orphan input section. An orphan section is one not specifically mentioned in a linker script. You may use this option multiple times on the command line; It prevents the normal merging of input sections with the same name, overriding output section assignments in a linker script.
| -v
--versionOn mac os sonoma as of 12/07/23:/usr/bin/ld
@(#)PROGRAM:ld PROJECT:dyld-1015.7
BUILD 18:48:48 Aug 22 2023
configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32
i386 x86_64 x86_64h armv6m armv7k armv7m armv7em
will use ld-classic for: armv6 armv7 armv7s arm64_32 i386 armv6m armv7k armv7m armv7em
LTO support using: LLVM version 15.0.0 (static support for 29, runtime is 29)
TAPI support using: Apple TAPI version 15.0.0 (tapi-1500.0.12.3)
Library search paths:
Framework search paths:
| -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 forELF 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.
| -z keyword
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 anELF "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 anELF "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 affectsELF 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 or not. --as-needed causes a DT_NEEDED tag to only be emitted for a library that satisfies an undefined symbol reference from a regular object file or, if the library is not found in the DT_NEEDED lists of other libraries linked up to that point, an undefined symbol reference from another dynamic library. --no-as-needed restores the default behaviour.
| --add-needed
--no-add-needed
These two options have been deprecated because of the similarity of their names to the --as-needed and --no-as-needed options. They have been replaced by --copy-dt-needed-entries and --no-copy-dt-needed-entries.
| -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 onELF 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 onELF 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 onELF 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 onELF platforms which support shared libraries.
The format of the dynamic list is the same as the version node without scope and node name. See VERSION for more information.
| --dynamic-list-data
Include all global data symbols to the dynamic list.
| --dynamic-list-cpp-new
Provide the builtin dynamic list for C ++ operator new and delete. It is mainly useful for building shared libstdc++.
| --dynamic-list-cpp-typeinfo
Provide the builtin dynamic list for C ++ runtime type identification.
| --check-sections
--no-check-sections
Asks the linker not to check section addresses after they have been assigned to see if there are any overlaps. Normally the linker will perform this check, and if it finds any overlaps it will produce suitable error messages. The linker does know about, and does make allowances for sections in overlays. The default behaviour can be restored by using the command line switch --check-sections. Section overlap is not usually checked for relocatable links. You can force checking in that case by using the --check-sections option.
| --copy-dt-needed-entries
--no-copy-dt-needed-entries
This option affects the treatment of dynamic libraries referred to by DT_NEEDED tags insideELF dynamic libraries mentioned on the command line. Normally the linker will add a DT_NEEDED tag to the output binary for each library mentioned in a DT_NEEDED tag in an input dynamic library. With --no-copy-dt-needed-entries specified on the command line however any dynamic libraries that follow it will have their DT_NEEDED entries ignored. The default behaviour can be restored with --copy-dt-needed-entries.
This option also has an effect on the resolution of symbols in dynamic libraries. With the default setting dynamic libraries mentioned on the command line will be recursively searched, following their DT_NEEDED tags to other libraries, in order to resolve symbols required by the output binary. With --no-copy-dt-needed-entries specified however the searching of dynamic libraries that follow it will stop with the dynamic library itself. No DT_NEEDED links will be traversed to resolve symbols.
| --cref
Output a cross reference table. If a linker map file is being generated, the cross reference table is printed to the map file. Otherwise, it is printed on the standard output.
The format of the table is intentionally simple, so that it may be easily processed by a script if necessary. The symbols are printed out, sorted by name. For each symbol, a list of file names is given. If the symbol is defined, the first file listed is the location of the definition. The remaining files contain references to the symbol.
| --no-define-common
This option inhibits the assignment of addresses to common symbols. The script command "INHIBIT_COMMON_ALLOCATION" has the same effect.
The --no-define-common option allows decoupling the decision to assign addresses to Common symbols from the choice of the output file type; otherwise a non-Relocatable output type forces assigning addresses to Common symbols. Using --no-define-common allows Common symbols that are referenced from a shared library to be assigned addresses only in the main program. This eliminates the unused duplicate space in the shared library, and also prevents any possible confusion over resolving to the wrong duplicate when there are many dynamic modules with specialized search paths for runtime symbol resolution.
| --defsym=symbol=expression
Create a global symbol in the output file, containing the absolute address given by expression. You may use this option as many times as necessary to define multiple symbols in the command line. A limited form of arithmetic is supported for the expression in this context: you may give a hexadecimal constant or the name of an existing symbol, or use "+" and "-" to add or subtract hexadecimal constants or symbols. If you need more elaborate expressions, consider using the linker command language from a script. Note: there should be no white space between symbol, the equals sign ("="), and expression.
| --demangle[=style]
--no-demangle
These options control whether to demangle symbol names in error messages and other output. When the linker is told to demangle, it tries to present symbol names in a readable fashion: it strips leading underscores if they are used by the object file format, and converts C ++ mangled symbol names into user readable names. Different compilers have different mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler. The linker will demangle by default unless the environment variable COLLECT_NO_DEMANGLE is set. These options may be used to override the default.
| -Ifile
--dynamic-linker=file
Set the name of the dynamic linker. This is only meaningful when generating dynamically linkedELF executables. The default dynamic linker is normally correct; don't use this unless you know what you are doing.
| --fatal-warnings
--no-fatal-warnings
Treat all warnings as errors. The default behaviour can be restored with the option --no-fatal-warnings.
| --force-exe-suffix
Make sure that an output file has a .exe suffix.
If a successfully built fully linked output file does not have a ".exe" or ".dll" suffix, this option forces the linker to copy the output file to one of the same name with a ".exe" suffix. This option is useful when using unmodified Unix makefiles on a Microsoft Windows host, since some versions of Windows won't run an image unless it ends in a ".exe" suffix.
| --gc-sections
--no-gc-sections
Enable garbage collection of unused input sections. It is ignored on targets that do not support this option. The default behaviour (of not performing this garbage collection) can be restored by specifying --no-gc-sections on the command line.
--gc-sections decides which input sections are used by examining symbols and relocations. The section containing the entry symbol and all sections containing symbols undefined on the command-line will be kept, as will sections containing symbols referenced by dynamic objects. Note that when building shared libraries, the linker must assume that any visible symbol is referenced. Once this initial set of sections has been determined, the linker recursively marks as used any section referenced by their relocations. See --entry and --undefined.
This option can be set when doing a partial link (enabled with option -r). In this case the root of symbols kept must be explicitely specified either by an --entry or --undefined option or by a "ENTRY" command in the linker script.
| --print-gc-sections
--no-print-gc-sections
List all sections removed by garbage collection. The listing is printed on stderr. This option is only effective if garbage collection has been enabled via the --gc-sections) option. The default behaviour (of not listing the sections that are removed) can be restored by specifying --no-print-gc-sections on the command line.
| --help
Print a summary of the command-line options on the standard output and exit.
| --target-help
Print a summary of all target specific options on the standard output and exit.
| -Map=mapfile
Print a link map to the file mapfile. See the description of the -M option, above.
| --no-keep-memory
ld normally optimizes for speed over memory usage by caching the symbol tables of input files in memory. This option tells ld to instead optimize for memory usage, by rereading the symbol tables as necessary. This may be required if ld runs out of memory space while linking a large executable.
| --no-undefined
-z defs
Report unresolved symbol references from regular object files. This is done even if the linker is creating a non-symbolic shared library. The switch --[no-]allow-shlib-undefined controls the behaviour for reporting unresolved references found in shared libraries being linked in.
| --allow-multiple-definition
-z muldefs
Normally when a symbol is defined multiple times, the linker will report a fatal error. These options allow multiple definitions and the first definition will be used.
| --allow-shlib-undefined
--no-allow-shlib-undefined
Allows or disallows undefined symbols in shared libraries. This switch is similar to --no-undefined except that it determines the behaviour when the undefined symbols are in a shared library rather than a regular object file. It does not affect how undefined symbols in regular object files are handled.
The default behaviour is to report errors for any undefined symbols referenced in shared libraries if the linker is being used to create an executable, but to allow them if the linker is being used to create a shared library.
The reasons for allowing undefined symbol references in shared libraries specified at link time are that:
• A shared library specified at link time may not be the same as the one that is available at load time, so the symbol might actually be resolvable at load time.
• There are some operating systems, eg BeOS and HPPA , where undefined symbols in shared libraries are normal.
The BeOS kernel for example patches shared libraries at load time to select whichever function is most appropriate for the current architecture. This is used, for example, to dynamically select an appropriate memset function.
| --no-undefined-version
Normally when a symbol has an undefined version, the linker will ignore it. This option disallows symbols with undefined version and a fatal error will be issued instead.
| --default-symver
Create and use a default symbol version (the soname) for unversioned exported symbols.
| --default-imported-symver
Create and use a default symbol version (the soname) for unversioned imported symbols.
| --no-warn-mismatch
Normally ld will give an error if you try to link together input files that are mismatched for some reason, perhaps because they have been compiled for different processors or for different endiannesses. This option tells ld that it should silently permit such possible errors. This option should only be used with care, in cases when you have taken some special action that ensures that the linker errors are inappropriate.
| --no-warn-search-mismatch
Normally ld will give a warning if it finds an incompatible library during a library search. This option silences the warning.
| --no-whole-archive
Turn off the effect of the --whole-archive option for subsequent archive files.
| --noinhibit-exec
Retain the executable output file whenever it is still usable. Normally, the linker will not produce an output file if it encounters errors during the link process; it exits without writing an output file when it issues any error whatsoever.
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