LD(1)

📦
version 2.46.1 · 5 versions
, in fedora 44

LD(1) 💖 the GNU linker, bestie edition

okay so this is the ld page from the GNU Development Tools manual, and we're doing it in 15 parts because it is long long. buckle up, we're starting now 🎀

✨ NAME ✨

ld — the GNU linker 🫶

✨ SYNOPSIS ✨

ld [options] objfile ...

✨ DESCRIPTION ✨

so basically ld takes a whole bunch of object and archive files, relocates their data, and ties up symbol references. it's giving matchmaker but for symbols fr fr. usually the very last step in compiling a program is running ld, and that's just how it is. periodt.

ld also accepts Linker Command Language files, which are written in a superset of AT&T's Link Editor Command Language syntax, so you get explicit and total control over the linking process. iconic behavior only 💅

heads up bestie — this man page does not describe the command language. for the full details on the command language and other aspects of the GNU linker, go read the ld entry in info. iykyk 📖

this version of ld uses the general purpose BFD libraries to operate on object files. what that means for you: ld can read, combine, and write object files in many different formats — for example, COFF or a.out. and yes, different formats can be linked together to produce any available kind of object file. the range? unmatched 🌈

aside from the flexibility, the GNU linker is genuinely more helpful than other linkers when it comes to diagnostic info. many linkers just abandon execution immediately the second they hit an error. but ld, whenever possible, keeps executing — which lets you spot other errors, or in some cases even get an output file in spite of the error. not me being emotionally supported by a linker 😭💖

the GNU linker ld is meant to cover a broad range of situations and to be as compatible as possible with other linkers. consequence of that: you have many choices to control its behavior. so many. an abundance. a plethora, even. 🦋

✨ OPTIONS ✨

okay so the linker supports a plethora of command-line options, but in actual practice only a few of them get 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 a system like that, to link a file hello.o, you'd do:

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, bestie, we'll get there 💜)

some of the command-line options to ld can be specified at any point in the command line. however — and this is the important bit — options which refer to files, like -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. order matters, no cap.

repeating non-file options with a different argument will either have no further effect, or override prior occurrences (the ones further to the left on the command line) of that option. options which can be meaningfully specified more than once are noted in the descriptions below, so watch for that.

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. do not do that. it's giving chaos 🙈

usually the linker is invoked with at least one object file, but you can specify other forms of binary input files using -l, -R, and the script command language. if no binary input files at all are specified, the linker does not produce any output, and issues the message No input files.

if the linker can't recognize the format of an object file, it will assume that it is a linker script. a script specified this way augments the main linker script used for the link — either the default linker script or the one you specified with -T. this feature lets the linker link against a file which looks like an object or an archive, but actually just defines some symbol values, or uses INPUT or GROUP to load other objects. specifying a script this way merely augments the main linker script, with the extra commands placed after the main script. if you want to replace the default linker script entirely, use the -T option instead — but note the effect of the INSERT command, bestie, don't say i didn't warn you.

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. no vibes-based spacing.

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. very different outcomes, be careful 💀

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 too. slay ✨

note — if the linker is being invoked indirectly, via a compiler driver (e.g. gcc), then all the linker command-line options should be prefixed by -Wl, (or whatever is appropriate for the particular compiler driver), like this:
gcc -Wl,--start-group foo.o bar.o -Wl,--end-group

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

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

here's a table of the generic command-line switches accepted by the GNU linker (it's a list here bestie, but same energy 💅):

  • @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. 🔁
  • --audit AUDITLIB — adds AUDITLIB to the DT_AUDIT 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_AUDIT will contain a colon separated list of audit interfaces to use. if the linker finds an object with an audit entry while searching for shared libraries, it will add a corresponding DT_DEPAUDIT entry in the output file. this option is only meaningful on ELF platforms supporting the rtld-audit interface. 👑
  • -b input-format, --format= input-format — ld may be configured to support more than one kind of object file. if your ld is configured this way, you can use the -b option to specify the binary format for input object files that follow this option on the command line. even when ld is configured to support alternative object formats, you don't usually need to specify this, as ld should be configured to expect as a default input format the most usual format on each machine. input-format is a text string, the name of a particular format supported by the BFD libraries. (you can list the available binary formats with objdump -i.)
    • you may want to use this option if you're linking files with an unusual binary format. you can also use -b to switch formats explicitly (when linking object files of different formats), by including -b input-format before each group of object files in a particular format.
    • the default format is taken from the environment variable GNUTARGET.
    • you can also define the input format from a script, using the command TARGET; 🌸
  • -c MRI-commandfile, --mri-script= MRI-commandfile — for compatibility with linkers produced by MRI, ld accepts script files written in an alternate, restricted command language, described in the MRI Compatible Script Files section of GNU ld documentation. introduce MRI script files with the option -c; use the -T option to run linker scripts written in the general-purpose ld scripting language. if MRI-cmdfile does not exist, ld looks for it in the directories specified by any -L options. 🔍
  • -d, -dc, -dp — these three options are equivalent; multiple forms are supported for compatibility with other linkers. they assign space to common symbols even if a relocatable output file is specified (with -r). the script command FORCE_COMMON_ALLOCATION has the same effect. three names, one vibe 💖
  • --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 on ELF platforms supporting the rtld-audit interface. the -P option is provided for Solaris compatibility. ⭐
  • --enable-linker-version — enables the LINKER_VERSION linker script directive, described in Output Section Data. if this directive is used in a linker script and this option has been enabled, then a string containing the linker version will be inserted at the current point. 🎀
note — the location of this option on the linker command line is significant. it will only affect linker scripts that come after it on the command line, or which are built into the linker.
  • --disable-linker-version — disables the LINKER_VERSION linker script directive, so that it does not insert a version string. this is the default. 🙈

okay that's part one bestie, and there's so much more coming, don't go anywhere 💜

  • --enable-non-contiguous-regions — okay bestie so normally if an input section doesn't fit its matching output section, ld throws hands and errors out. This option says "no, we're not doing that" and instead lets the linker try to drop that input section into subsequent matching output sections instead. It only errors if literally no output section is big enough. Super handy when you've got several non-contiguous memory regions and the input section doesn't care which one it lands in. 🦋

The order input sections get evaluated in does not change. Example time:

MEMORY {
  MEM1 (rwx) : ORIGIN = 0x1000, LENGTH = 0x14
  MEM2 (rwx) : ORIGIN = 0x1000, LENGTH = 0x40
  MEM3 (rwx) : ORIGIN = 0x2000, LENGTH = 0x40
}
SECTIONS {
  mem1 : { *(.data.*); } > MEM1
  mem2 : { *(.data.*); } > MEM2
  mem3 : { *(.data.*); } > MEM3
}

with input sections:

.data.1: size 8
.data.2: size 0x10
.data.3: size 4

results in .data.1 affected to mem1, and .data.2 and .data.3 affected to mem2, even though .data.3 would fit in mem3.

Heads up babes: this option is incompatible with INSERT statements because it changes the way input sections are mapped to output sections. No cap. 💅
  • --enable-non-contiguous-regions-warnings — this one turns on warnings for when --enable-non-contiguous-regions allows possibly unexpected matches in sections mapping. Why do we care? Because otherwise you could silently discard a section instead of failing just because it doesn't fit any output region. 😭 Watch out for it.
  • -e entry / --entry=entry — use entry as the explicit symbol for where your program starts executing, instead of the default entry point. If there's no symbol named entry, the linker will try to parse entry as a number and use that as the entry address. The number gets interpreted in base 10, but you can slap a leading 0x for base 16, or a leading 0 for base 8. 🎀 For i386 PE, entry can also be the original function name (without the leading underscore and/or the trailing stdcall @number when applicable).
  • --exclude-libs lib,lib,... — gives a list of archive libraries whose symbols should not be automatically exported. The library names can be delimited by commas or colons. If you say --exclude-libs ALL, that excludes symbols in all archive libraries from automatic export. ⭐

This option is only available 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 get treated as hidden.

  • --exclude-modules-for-implib module,module,... — lists object files or archive members whose symbols should not be automatically exported, but which should still be copied wholesale into the import library being generated during the link. 🫶 The module names can be delimited by commas or colons, and they have to match exactly the filenames used by ld to open the files. For archive members, that's just the member name — but for object files, the name you list 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 you're creating a dynamically linked executable, using -E or --export-dynamic makes the linker add all symbols to the dynamic symbol table. And the dynamic symbol table is the set of symbols visible from dynamic objects at run time. 👑

If you don't use either of these options (or you use --no-export-dynamic to restore the default behavior), the dynamic symbol table will normally only contain those symbols 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'll probably need this option when linking the program itself.

You can also use the dynamic list to control what symbols get added to the dynamic symbol table, if the output format supports it. See the description of --dynamic-list.

Note that this option is specific to ELF targeted ports. PE targets support a similar function to export all symbols from a DLL or EXE — see the description of --export-all-symbols below.
  • --export-dynamic-symbol=glob — when creating a dynamically linked executable, symbols matching glob get added to the dynamic symbol table. When creating a shared library, references to symbols matching glob will not be bound to the definitions within the shared library. This option is a no-op when creating a shared library and -Bsymbolic or --dynamic-list are not specified. Only meaningful on ELF platforms which support shared libraries. 💜
  • --export-dynamic-symbol-list=file — specify a --export-dynamic-symbol for each pattern in the file. The format of the file is the same as the version node without scope and node name. See VERSION for more info.
  • -EB — link big-endian objects. This affects the default output format.
  • -EL — link little-endian objects. This affects the default output format.
  • -f name / --auxiliary=name — when creating an ELF shared object, set the internal DT_AUXILIARY field to the specified name. This tells the dynamic linker that the symbol table of the shared object should be used as an auxiliary filter on the symbol table of the shared object name.

If you later link a program against this filter object, then when you run the program, the dynamic linker will see the DT_AUXILIARY field. If the dynamic linker resolves any symbols from the filter object, it will first check whether there's a definition in the shared object name. If there is one, it'll be used instead of the definition in the filter object. The shared object name need not exist. So name can be used to provide an alternative implementation of certain functions — maybe for debugging, or for machine-specific performance. ✨

This option can be specified more than once. The DT_AUXILIARY entries get created in the order 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 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. It'll resolve symbols according to the symbol table of the filter object as usual, but it'll actually link to the definitions found in the shared object name. So the filter object can be used to select a subset of the symbols provided by the object name. 🦋

Some older linkers used -F throughout a compilation toolchain for specifying object-file format for both input and output object files. The GNU linker uses other mechanisms for this: 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. Just vibes. 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. Only meaningful for object file formats like MIPS ELF that support putting large and small objects into different sections. 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 that 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 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 can 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'll search the library path for a file called libnamespec.a.

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

The linker will search an archive only once, at the location where it's specified on the command line. If the archive defines a symbol which was undefined in some object that 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 can list the same archive multiple times on the command line.

This type of archive searching is standard for Unix linkers, bestie. But heads up if you're running ld on AIX — it does NOT behave like the AIX linker. Different vibes entirely. 🙈

  • -L searchdir / --library-path=searchdir — okay so this is the "where do I look for my stuff" option 💅. It adds searchdir to the list of paths that ld will search for archive libraries and ld control scripts. Use it as many times as you want, fr fr — no cap on that. The directories get searched in the order you typed them on the command line, and anything you specify on the command line gets searched before the default directories.

✨ And here's the iconic part: all -L options apply to all -l options, no matter what order they appear in. Order does not matter for that, periodt. BUT — -L options do not affect how ld searches for a linker script unless the -T option is specified. That distinction matters, iykyk.

If searchdir begins with "=" or $SYSROOT, then that prefix gets replaced by the sysroot prefix, which is controlled by the --sysroot option — or specified when the linker was configured.

The default set of paths searched (the ones you get when you don't use -L at all) depends on which emulation mode ld is using, and in some cases also on how it was configured. Vibe check depends on the build, basically.

You can also specify the paths inside a link script with the "SEARCH_DIR" command. Directories specified that way get searched at the point where the linker script appears in the command line. 📍

  • -m emulation — emulate the emulation linker, babe. You can list the available emulations with the --verbose or -V options if you wanna go window shopping 🛍️. If you don't use -m, the emulation is taken from the "LDEMULATION" environment variable, if that's defined. Otherwise? The default emulation depends on how the linker was configured. Mystery solved. 🕵️‍♀️
  • --remap-inputs=pattern=filename / --remap-inputs-file=file — ooooh these are fun, lowkey chaotic but fun 🎀. These options let you change the names of input files before the linker even tries to open them. So --remap-inputs=foo.o=bar.o means any attempt to load a file called foo.o will instead try to load a file called bar.o. Wildcard patterns are allowed in the first filename too, so --remap-inputs=foo*.o=bar.o will rename any input file matching foo*.o to bar.o. Slay. ✨

There's an alternative form, --remap-inputs-file=filename, that lets you read the remappings from a file instead. Each line in the file can hold a single remapping. Blank lines get ignored. Anything from a hash character (#) to the end of a line counts as a comment and also gets ignored 💅. The mapping pattern can be separated from the filename by whitespace or by an equals (=) character. Either one works.

You can specify these options multiple times and their contents accumulate. The remappings get processed in the order they occur on the command line, and if they come from a file, in the order they occur in that file. And once a match is made, no further checking for that filename will be performed. One and done, no second chances.

Here's the sneaky little trick 👀: if the replacement filename is /dev/null or just NUL, then the remapping will actually cause the input file to be ignored. Genuinely a convenient way to experiment with removing input files from a complicated build environment. Iconic for debugging ngl.

Note that this option is position dependent and only affects filenames that come after it on the command line. So:
          ld foo.o --remap-inputs=foo.o=bar.o

will have no effect, whereas:

          ld --remap-inputs=foo.o=bar.o foo.o

will rename the input file foo.o to bar.o. Order matters bestie, don't forget it 😭.

Note — these options also affect files referenced by INPUT statements in linker scripts. But since linker scripts are processed after the entire command line is read, the position of the remap options on the command line is not significant for that case. Confusing? A little. Correct? Yes.

If the verbose option is enabled then any mappings that match will be reported — although again, the verbose option needs to be enabled on the command line before the remapped filenames appear. Timing is everything, babes ⏰.

If the -Map or --print-map options are enabled then the remapping list will be included in the map output. Receipts. 🧾

  • -M / --print-map — print a link map to the standard output 📜. A link map gives you the tea about the link, including:
    • 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 that involves a reference to a previous value of the same symbol may not have the 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. So 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. 📚

  • How GNU properties are merged.

When the linker merges input .note.gnu.property sections into one output .note.gnu.property section, some properties are removed or updated. These actions are reported in the link map. For example:

        Removed property 0xc0000002 to merge foo.o (0x1) and bar.o (not found)

This indicates that property 0xc0000002 is removed from output when merging properties in foo.o, whose property 0xc0000002 value is 0x1, and bar.o, which doesn't have property 0xc0000002.

        Updated property 0xc0010001 (0x1) to merge foo.o (0x1) and bar.o (0x1)

This indicates that property 0xc0010001 value is updated to 0x1 in output when merging properties in foo.o, whose 0xc0010001 property value is 0x1, and bar.o, whose 0xc0010001 property value is 0x1.

  • On some ELF targets, a list of fixups inserted by --relax:
        foo.o: Adjusting branch at 0x00000008 towards "far" in section .text

This indicates that the branch at 0x00000008 in foo.o, targeting the symbol "far" in section .text, has been replaced by a trampoline. 🦘

  • --print-map-discarded / --no-print-map-discarded — print (or don't print, your call 💅) the list of discarded and garbage collected sections in the link map. Enabled by default.
  • --print-map-locals / --no-print-map-locals — print (or don't print) local symbols in the link map. Local symbols will have the text (local) printed before their name, and will be listed after all of the global symbols in a given section. Temporary local symbols (typically those that start with .L) will not be included in the output. Disabled by default.
  • -n / --nmagic — turn off page alignment of sections, and disable linking against shared libraries. If the output format supports Unix style magic numbers, mark the output as "NMAGIC". ✨
  • -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. So like… technically allowed, but not correct. 😬
  • --no-omagic — this one 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 that. Don't get it twisted 💅
  • -o output / --output=output — use output as the name for the program produced by ld 🎀. If you don't specify this option, the name a.out is used by default. The script command "OUTPUT" can also specify the output file name. Multiple ways to name your baby, iconic.
Note — the linker will delete the output file before it starts to write to it. It will do this even if it turns out that the link cannot be completed due to errors. Yes really. It's gone. 😭
Note — the linker will check to make sure that the output file name does not match the name of any of the input files, but that is all. In particular it will not complain if the output file might overwrite a source file or some other important file. Therefore in build systems it is recommended to use the -o option as the last option on the linker command line. For example consider:
          ld -o $(EXE) $(OBJS)
          ld $(OBJS) -o $(EXE)

If the EXE variable is not defined for some reason, the first version of the linker command could end up deleting one of the object files (the first one in the OBJS list) whereas the second version of the linker command will generate an error message and not delete anything. Order your args, bestie, it's literally saving your files. 🫶

  • --dependency-file=depfile — write a dependency file to depfile 📝. This file contains a rule suitable for "make" describing the output file and all the input files that were read to produce it. The output is similar to the compiler's output with -M -MP.
Note that there is no option like the compiler's -MM, to exclude "system files" (which is not a well-specified concept in the linker, unlike "system headers" in the compiler). So the output from --dependency-file is always specific to the exact state of the installation where it was produced, and should not be copied into distributed makefiles without careful editing. No copy-paste shortcuts here, sorry babe. 🙈
  • -O level — if level is a numeric value greater than zero, ld optimizes the output. This might take significantly longer and therefore probably should only be enabled for the final binary ⏳. At the moment this option only affects ELF shared library generation. Future releases of the linker may make more use of this option. Also, currently there is no difference in the linker's behaviour for different non-zero values of this option. Again, this may change with future releases. Stay tuned I guess 💜
  • -plugin name — plugs a plugin into the linking process, bestie. The name is the absolute filename of the plugin 💅 Usually your compiler adds this by itself when it's doing link time optimization, but you're absolutely allowed to bring your own plugins if you want.

Heads up tho: where compiler-originated plugins live is not the same place where ar, nm and ranlib go looking for their plugins. So for those commands to use a compiler based plugin, you first gotta copy it into the ${libdir}/bfd-plugins directory. All gcc based linker plugins are backward compatible, so literally just copy in the newest one and you're good 🫶

  • --push-state — this one lets you preserve the current state of all the flags that govern input file handling, so you can bring them all back with one matching --pop-state. It's giving save-point energy ✨

The options it covers are: -Bdynamic, -Bstatic, -dn, -dy, -call_shared, -non_shared, -static, -N, -n, --whole-archive, --no-whole-archive, -r, -Ur, --copy-dt-needed-entries, --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.

One big target for this is pkg-config specifications. When you use it with the --libs option, all possibly needed libraries get listed and then possibly linked with all the time 😭 It's better to return something like this:

-Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state
  • --pop-state — undoes the whole effect of --push-state, restoring the previous values of the flags governing input file handling. Rewind button 🎀
  • -q, --emit-relocs — leaves relocation sections and their contents in fully linked executables. Post link analysis and optimization tools may need this info to correctly modify executables. Downside? Bigger executables, no cap 📦

This option is currently only supported on ELF platforms.

  • --force-dynamic — forces the output file to have dynamic sections. This one is specific to VxWorks targets, iykyk.
  • -r, --relocatable — generates relocatable output, i.e. an output file that can itself serve as input to ld. Everybody calls this 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 you don't specify this option, an absolute file is produced instead. And when you're linking C++ programs, this option will not resolve references to constructors — for that you need -Ur.

When an input file doesn't have the same format as the output file, partial linking is only supported if that input file contains no relocations. Different output formats can have further restrictions; for example some a.out-based formats don't support partial linking with input files in other formats at all 😬

When the relocatable output contains both contents which require link-time optimization (LTO) and contents which don't require LTO, a .gnu_object_only section will be created to contain a relocatable object file, as if -r is applied to all relocatable inputs which don't require LTO. When processing a relocatable input with a .gnu_object_only section, the linker will extract the .gnu_object_only section as a separate input.

Note that since -r groups some sections from different input files together, there may be negative impacts on code size and locality in the final executable or shared library. Consider yourself warned 💀

This option does the same thing as -i.

  • -R filename, --just-symbols=filename — reads symbol names and their addresses from filename, but does not relocate it or include it in the output. This lets your output file 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 -R is followed by a directory name rather than a file name, it gets treated as the -rpath option. Sneaky but iconic.

  • --rosegment, --no-rosegment — tries to make sure only a single read-only, non-code segment is created. Only useful when used together with the -z separate-code option. The resulting binaries should be smaller than if -z separate-code is used on its own. Without this option, or if --no-rosegment is specified, the -z separate-code option will create two read-only segments — one before the code segment and one after it 🌈

The names of the options are misleading, but they were chosen so the linker stays compatible with the LLD and GOLD linkers. Blame the ancestors, not us 🙈

These options are only supported by ELF targets.

  • -s, --strip-all — omits all symbol information from the output file. Gone. Deleted. Periodt 💅
  • -S, --strip-debug — omits debugger symbol information (but not all symbols) from the output file. So like, a soft strip 🎀
  • --strip-discarded, --no-strip-discarded — omits (or doesn't omit) global symbols defined in discarded sections. Enabled by default ✨
  • -plugin-save-temps — stores the plugin "temporary" intermediate files permanently. No more vanishing acts 🦋
  • -t, --trace — prints the names of the input files as ld processes them. If -t is given twice, then members within archives are also printed. -t output is useful for generating a list of all the object files and scripts involved in linking — for example when packaging files for a linker bug report 🐛
  • -T scriptfile, --script=scriptfile — uses scriptfile as the linker script. This script replaces ld's default linker script (rather than adding to it), unless the script contains INSERT, so the commandfile must specify everything necessary to describe the output file.

If scriptfile doesn't exist in the current directory, ld looks for it in the directories specified by any preceding -L options.

Command line options that appear before the -T option can affect the script, but command line options that appear after it do not.

Multiple -T options will accumulate if they are augmenting the current script; otherwise the last, non-augmenting, -T option will be used.

There are other ways of specifying linker scripts. See

  • -dT scriptfile, --default-script=scriptfile — uses 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. That lets options placed after the --default-script option on the command line affect the behaviour of the linker script — which can be important when the linker command line can't be directly controlled by the user (eg because the command line is being constructed by another tool, such as gcc) 🧚

  • -u symbol, --undefined=symbol — forces 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.

If you're using this option to force additional modules to be pulled into the link, and it's an error for the symbol to remain undefined, then you should use --require-defined instead 💖

  • --require-defined=symbol — requires that symbol is defined in the output file. This option is the same as --undefined except that if symbol is not defined in the output file, the linker will issue an error and exit 😭 The same effect can be achieved in a linker script by using EXTERN, ASSERT and DEFINED together. This option can be used multiple times to require additional symbols.
  • -Ur — for programs that don't use constructors or destructors, or for ELF based systems, this option is equivalent to -r: it generates relocatable output, i.e. an output file that can itself serve as input to ld. For other binaries, though, -Ur is similar to -r but it also resolves references to constructors and destructors 👑

For those systems where -r and -Ur behave differently, 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. So use -Ur only for the last partial link, and -r for all the others. Order matters, bestie 🫶

  • --orphan-handling=MODE — controls how orphan sections are handled. An orphan section is one not specifically mentioned in a linker script 🥺

MODE can have any of the following values:

  • place — orphan sections are placed into a suitable output section following the strategy described in Orphan Sections. The option --unique also affects how sections are placed.
  • discard — all orphan sections are discarded, by placing them in the /DISCARD/ section.
  • warn — the linker will place the orphan section as for place and also issue a warning.
  • error — the linker will exit with an error if any orphan section is found.

The default if --orphan-handling is not given is place.

  • --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 — displays the version number for ld. The -V option also lists the supported emulations. See also the description of the --enable-linker-version in Options,,Command-line Options, which can be used to insert the linker version string into a binary ⭐
  • -x, --discard-all — deletes all local symbols. Bye bye 🦋
  • -X, --discard-locals — deletes 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 — prints the name of each linked file in which symbol appears. This option may be given any number of times. On many systems it's necessary to prepend an underscore 🙈

This option is useful when you have an undefined symbol in your link but have no idea where the reference is coming from. Detective mode activated 🔍

  • -Y path — adds path to the default library search path. This one is here purely for Solaris compatibility, bestie — it's a legacy courtesy, not a personality trait. 💜
  • -z keyword — okay so -z is the little command center where you drop keywords that tune how the linker behaves. Here are all the keywords it recognizes, no skips, no cap:
    • call-nop=prefix-addr
    • call-nop=suffix-nop
    • call-nop=prefix-byte
    • call-nop=suffix-byte — these four pick which 1-byte "NOP" padding gets used when an indirect call to a locally defined function, foo, gets transformed to go through its GOT slot. The tea: call-nop=prefix-addr generates "0x67 call foo". call-nop=suffix-nop generates "call foo 0x90". call-nop=prefix-byte generates "byte call foo". And call-nop=suffix-byte generates "call foo byte". Supported for i386 and x86_64. 🦋
    • cet-report=none
    • cet-report=warning
    • cet-report=error — this is how you tell the linker to complain (or not) about missing GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK properties in the input .note.gnu.property section. cet-report=none is the default and means the linker stays chill and reports nothing about missing properties in input files. cet-report=warning makes it issue a warning for missing properties in input files. cet-report=error makes it straight up error out for missing properties in input files. Heads up: ibt will turn off the missing GNU_PROPERTY_X86_FEATURE_1_IBT property report, and shstk will turn off the missing GNU_PROPERTY_X86_FEATURE_1_SHSTK property report. Supported for Linux/i386 and Linux/x86_64. ✨
    • combreloc
    • nocombreloc — combine multiple dynamic relocation sections and sort them to improve dynamic symbol lookup caching. nocombreloc means don't do this. 🎀
    • common
    • nocommon — generate common symbols with STT_COMMON type during a relocatable link. With nocommon, use STT_OBJECT type instead. 🌸
    • common-page-size=value — sets the most commonly used page size to value. Memory image layout gets optimized to minimize memory pages if the system is running pages of this size. 💅
    • defs — reports unresolved symbol references coming from regular object files. It does this even if the linker is creating a non-symbolic shared library. This option is the exact inverse of -z undefs. 🔥
    • dynamic-undefined-weak
    • nodynamic-undefined-weak — makes undefined weak symbols dynamic when building a dynamic object, but only if they're referenced from a regular object file and aren't forced local by symbol visibility or versioning. nodynamic-undefined-weak means don't make them dynamic. If you give neither option, a target may default to either one being in force, or it may make some other selection of undefined weak symbols dynamic. Also ngl: not all targets support these options. 😭
    • execstack — marks the object as requiring an executable stack. 🫶
    • global — only meaningful when you're building a shared object. It makes the symbols defined by this shared object available for symbol resolution of libraries loaded afterwards. 👑
    • globalaudit — only meaningful when building a dynamic executable. It marks the executable as requiring global auditing by setting the "DF_1_GLOBAUDIT" bit in the "DT_FLAGS_1" dynamic tag. Global auditing requires that any auditing library defined via the --depaudit or -P command-line options be run for all dynamic objects loaded by the application. 💖
    • ibtplt — generates Intel Indirect Branch Tracking (IBT) enabled PLT entries. Supported for Linux/i386 and Linux/x86_64. 🌈
    • ibt — generates GNU_PROPERTY_X86_FEATURE_1_IBT in the .note.gnu.property section to indicate compatibility with IBT. This also implies ibtplt. Supported for Linux/i386 and Linux/x86_64. ⭐
    • indirect-extern-access
    • noindirect-extern-access — generates GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS in the .note.gnu.property section to indicate that the object file requires canonical function pointers and cannot be used with copy relocation. This option also implies noextern-protected-data and nocopyreloc. Supported for i386 and x86-64. Meanwhile noindirect-extern-access removes GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS from the .note.gnu.property section. 🦋
    • initfirst — only meaningful when building a shared object. It marks the object so that its runtime initialization happens before the runtime initialization of any other objects brought into the process at the same time. And symmetrically, the runtime finalization of the object happens after the runtime finalization of any other objects. Main character ordering, fr. 👑
    • interpose — tells the dynamic loader to modify its symbol search order so that symbols in this shared library interpose all other shared libraries not so marked. 💅
    • unique
    • nounique — when generating a shared library or other dynamically loadable ELF object, marks it as one that should (by default) only ever be loaded once, and only in the main namespace (when using "dlmopen"). This is mainly for marking fundamental libraries like libc, libpthread et al, which don't usually work right unless they're the sole instances of themselves. This behaviour can be overridden by the "dlmopen" caller, and it does not apply to certain loading mechanisms (like audit libraries). 🎀
    • lam-u48 — generates GNU_PROPERTY_X86_FEATURE_1_LAM_U48 in the .note.gnu.property section to indicate compatibility with Intel LAM_U48. Supported for Linux/x86_64. ✨
    • lam-u57 — generates GNU_PROPERTY_X86_FEATURE_1_LAM_U57 in the .note.gnu.property section to indicate compatibility with Intel LAM_U57. Supported for Linux/x86_64. ✨
    • lam-u48-report=none
    • lam-u48-report=warning
    • lam-u48-report=error — controls how the linker reports the missing GNU_PROPERTY_X86_FEATURE_1_LAM_U48 property in the input .note.gnu.property section. lam-u48-report=none is the default and means no reporting of missing properties in input files. lam-u48-report=warning issues a warning for missing properties in input files. lam-u48-report=error issues an error for missing properties in input files. Supported for Linux/x86_64. 🌸
    • lam-u57-report=none
    • lam-u57-report=warning
    • lam-u57-report=error — same deal, but for the missing GNU_PROPERTY_X86_FEATURE_1_LAM_U57 property in the input .note.gnu.property section. lam-u57-report=none is the default and reports nothing about missing properties in input files. lam-u57-report=warning issues a warning for missing properties in input files. lam-u57-report=error issues an error for missing properties in input files. Supported for Linux/x86_64. 🌸
    • lam-report=none
    • lam-report=warning
    • lam-report=error — the combo meal: this controls reporting for the missing GNU_PROPERTY_X86_FEATURE_1_LAM_U48 and GNU_PROPERTY_X86_FEATURE_1_LAM_U57 properties in the input .note.gnu.property section. lam-report=none is the default and reports nothing about missing properties in input files. lam-report=warning issues a warning for missing properties in input files. lam-report=error issues an error for missing properties in input files. Supported for Linux/x86_64. 💜
    • lazy — when generating an executable or shared library, marks it to tell the dynamic linker to defer function call resolution until the moment the function is actually called (lazy binding), instead of resolving at load time. Btw lazy binding is the default. 😌
    • loadfltr — specifies that the object's filters be processed immediately at runtime. 🔥
    • max-page-size=value — sets the maximum supported memory page size to value. 🌈
    • mark-plt
    • nomark-plt — marks PLT entries with dynamic tags, DT_X86_64_PLT, DT_X86_64_PLTSZ and DT_X86_64_PLTENT. Now listen, because this one is a big deal: since this option stores a non-zero value in the r_addend field of R_X86_64_JUMP_SLOT relocations, the resulting executables and shared libraries are incompatible with dynamic linkers such as those in older versions of glibc that don't have the change to ignore r_addend in R_X86_64_GLOB_DAT and R_X86_64_JUMP_SLOT relocations — those linkers don't ignore the r_addend field of R_X86_64_JUMP_SLOT relocations. Supported for x86_64. 💀
    • muldefs — allow multiple definitions. Let them all exist, bestie. 🫶
    • nocopyreloc — disables linker generated .dynbss variables used in place of variables defined in shared libraries. Warning: this may result in dynamic text relocations. 😭
    • nodefaultlib — specifies that the dynamic loader's search for dependencies of this object should ignore any default library search paths. 🎀
    • nodelete — specifies that the object shouldn't be unloaded at runtime. It stays. Periodt. 💅
    • nodlopen — specifies that the object is not available to "dlopen". 🙈
    • nodump — specifies that the object can not be dumped by "dldump". 🙈
    • noexecstack — marks the object as not requiring an executable stack. 🦋
    • noextern-protected-data — don't treat protected data symbols as external when building a shared library. This option overrides the linker backend default. It can be used to work around incorrect relocations against protected data symbols generated by the compiler. Heads up though: updates on protected data symbols by another module aren't visible to the resulting shared library. Supported for i386 and x86-64. ⚠️
    • noreloc-overflow — disables the relocation overflow check. You can use this to disable relocation overflow checking if there will be no dynamic relocation overflow at run-time. Supported for x86_64. 🔥
    • memory-seal
    • nomemory-seal — instructs the executable or shared library that all PT_LOAD segments should be sealed to avoid further manipulation (like changing the protection flags, the segment size, or removing the mapping). This is a security hardening and it requires system support. It generates GNU_PROPERTY_MEMORY_SEAL in the .note.gnu.property section. 🔒✨
  • now — when you're making an executable or a shared library, this stamps it so the dynamic linker resolves all the symbols right when the program starts (or when the shared library gets loaded by dlopen), instead of being like "eh, we'll figure out that function call later" and deferring it to the first time the function is actually called. eager, not lazy 💅
  • origin — says the object needs $ORIGIN handling in its paths. iykyk
  • pack-relative-relocs / nopack-relative-relocs — makes compact relative relocations in a position-independent executable and shared library. It adds "DT_RELR", "DT_RELRSZ" and "DT_RELRENT" entries to the dynamic section. Bestie, it gets ignored when you're building a position-dependent executable or relocatable output. nopack-relative-relocs is the default, which disables the compact relative relocation thing. When you link against the GNU C Library, a GLIBC_ABI_DT_RELR symbol version dependency on the shared C Library gets added to the output. Supported for i386 and x86-64. ✨
  • relro / norelro — creates an ELF "PT_GNU_RELRO" segment header in the object. That's a memory segment that should be made read-only after relocation, if it's supported. Heads up: specifying common-page-size smaller than the system page size will render this protection ineffective 😭. norelro means don't create that ELF "PT_GNU_RELRO" segment.
  • report-relative-reloc — reports the dynamic relative relocations generated by the linker. Supported for Linux/i386 and Linux/x86_64.
  • sectionheader / nosectionheader — generate the section header. nosectionheader means don't generate it. sectionheader is the default, periodt.
  • separate-code / noseparate-code — creates a separate code "PT_LOAD" segment header in the object. This one says: this memory segment holds only instructions and must live in wholly disjoint pages from any other data. noseparate-code means don't create that separate code "PT_LOAD" segment.
  • shstk — generates GNU_PROPERTY_X86_FEATURE_1_SHSTK in the .note.gnu.property section to show compatibility with Intel Shadow Stack. Supported for Linux/i386 and Linux/x86_64. 🛡️
  • stack-size=value — sets a stack size for an ELF "PT_GNU_STACK" segment. If you specify zero, it overrides any default non-zero sized "PT_GNU_STACK" segment creation.
  • start-stop-gc / nostart-stop-gc — okay so when --gc-sections is in effect, a reference from a retained section to "__start_SECNAME" or "__stop_SECNAME" causes all input sections named "SECNAME" to also be retained — but only if "SECNAME" is representable as a C identifier and either "__start_SECNAME" or "__stop_SECNAME" is synthesized by the linker. -z start-stop-gc disables that whole effect, letting sections get garbage collected as if those special synthesized symbols were never defined. -z start-stop-gc has no effect on a definition of "__start_SECNAME" or "__stop_SECNAME" in an object file or linker script. Such a definition will prevent the linker from providing a synthesized "__start_SECNAME" or "__stop_SECNAME" respectively, and therefore it also kills the special treatment by garbage collection for those references.
  • start-stop-visibility=value — sets the ELF symbol visibility for synthesized "__start_SECNAME" and "__stop_SECNAME" symbols. value must be exactly default, internal, hidden, or protected. If no -z start-stop-visibility option is given, protected is used for compatibility with historical practice. BUT — and this is a big but — it's highly recommended to use -z start-stop-visibility=hidden in new programs and shared libraries so these symbols don't get exported between shared objects, which is not usually what you intended. 🙈
  • text / notext / textoff — report an error if DT_TEXTREL is set, i.e. if the position-independent or shared object has dynamic relocations in read-only sections. notext or textoff means don't report an error.
  • undefs — do not report unresolved symbol references from regular object files, whether you're creating an executable or a shared library. This option is the inverse of -z defs. chaotic but okay
  • unique-symbol / nounique-symbol — avoids duplicated local symbol names in the symbol string table. If unique-symbol is used, it appends "."number"" to duplicated local symbol names. nounique-symbol is the default.
  • x86-64-baseline / x86-64-v2 / x86-64-v3 / x86-64-v4 — specify the x86-64 ISA level needed in the .note.gnu.property section. x86-64-baseline generates "GNU_PROPERTY_X86_ISA_1_BASELINE". x86-64-v2 generates "GNU_PROPERTY_X86_ISA_1_V2". x86-64-v3 generates "GNU_PROPERTY_X86_ISA_1_V3". x86-64-v4 generates "GNU_PROPERTY_X86_ISA_1_V4". Supported for Linux/i386 and Linux/x86_64. 🏆
  • isa-level-report=none / isa-level-report=all / isa-level-report=needed / isa-level-report=used — how to report x86-64 ISA levels in input relocatable files. isa-level-report=none, which is the default, makes the linker not report x86-64 ISA levels in input files. isa-level-report=all makes it report both needed and used x86-64 ISA levels in input files. isa-level-report=needed makes it report needed x86-64 ISA levels in input files. isa-level-report=used makes it report used x86-64 ISA levels in input files. Supported for Linux/i386 and Linux/x86_64.
Other keywords are ignored for Solaris compatibility. not our problem bestie 💅
  • --gnu-tls-tag / --no-gnu-tls-tag — adds a "GLIBC_ABI_GNU_TLS" version tag dependency in output programs and shared libraries when linking against glibc, if input relocatable object files call "___tls_get_addr". The output will fail to load and run at run-time against glibc that doesn't define the "GLIBC_ABI_GNU_TLS" version tag. Unless it's disabled by the --disable-gnu-tls-tag configure option at linker build time, when no options are specified the linker will add the "GLIBC_ABI_GNU_TLS" version tag dependency if inputs have a "___tls_get_addr" call and libc.so defines the "GLIBC_ABI_GNU_TLS" version tag. Supported for Linux/i386.
  • --gnu2-tls-tag / --no-gnu2-tls-tag — adds a "GLIBC_ABI_GNU2_TLS" version tag dependency in output programs and shared libraries when linking against glibc, if input relocatable object files have an "R_386_TLS_DESC_CALL" or "R_X86_64_TLSDESC_CALL" relocation. The output will fail to load and run at run-time against glibc that doesn't define the "GLIBC_ABI_GNU2_TLS" version tag. Unless it's disabled by the --disable-gnu2-tls-tag configure option at the linker build time, when no options are specified the linker will add the "GLIBC_ABI_GNU2_TLS" version tag dependency if inputs have an "R_386_TLS_DESC_CALL" or "R_X86_64_TLSDESC_CALL" relocation and libc.so defines the "GLIBC_ABI_GNU2_TLS" version tag. Supported for Linux/i386 and Linux/x86_64. 🔥
  • -( archives -) / --start-group archives --end-group — the archives should be a list of archive files. They can be explicit file names, or -l options.

The archives you specified get searched repeatedly until no new undefined references pop up. Normally an archive is searched only once, in the order it appears on the command line. So if a symbol in that archive is needed to resolve an undefined symbol referred to by an object in an archive that shows up later on the command line, the linker wouldn't be able to resolve that reference. By grouping the archives, they all get searched repeatedly until all possible references are resolved. 🌀

Using this option has a significant performance cost. Bestie, it's 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 can't be recognised. The assumption is that the user knows what they're doing and deliberately wants to link in these unknown input files. This was the default behaviour of the linker before release 2.14. From release 2.14 onwards the default is to reject such input files, so --accept-unknown-input-arch was added to restore the old behaviour. nostalgia core
  • --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 adds a DT_NEEDED tag for every dynamic library mentioned on the command line, regardless of whether the library is actually needed or not. --as-needed means a DT_NEEDED tag is only emitted for a library that, at that point in the link, satisfies a non-weak undefined symbol reference from a regular object file — or, if the library isn't found in the DT_NEEDED lists of other needed libraries, a non-weak undefined symbol reference from another needed dynamic library. Object files or libraries appearing on the command line after the library in question do not affect whether the library is seen as needed. This is similar to the rules for extraction of object files from archives. --no-as-needed restores the default behaviour.
Note: on Linux based systems the --as-needed option also has an affect on the behaviour of the --rpath and --rpath-link options. See the description of --rpath-link for more details. 👀
  • --add-needed / --no-add-needed — these two options have been deprecated because of how similar their names are to --as-needed and --no-as-needed. They've been replaced by --copy-dt-needed-entries and --no-copy-dt-needed-entries. rip bozo, use the new ones 🫶
  • -assert keyword — this option is ignored for SunOS compatibility.
  • -Bdynamic / -dy / -call_shared — link against dynamic libraries. This is only meaningful on platforms where shared libraries are supported. On such platforms this option is normally the default. The different variants of this option exist for compatibility with various systems. You can use this option multiple times on the command line: it affects library searching for -l options that follow it. ✨
  • -Bgroup — bestie, this one sets the DF_1_GROUP flag in the DT_FLAGS_1 entry in the dynamic section ✨. It makes the runtime linker handle lookups in this object and its dependencies only inside the group. Also, --unresolved-symbols=report-all is implied. This option is only meaningful on ELF platforms which support shared libraries. No cap.
  • -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. Iconic behaviour, honestly.
  • -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. It’s giving “mine, mine, mine” 🫶.
  • -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. Functions only, bestie 💖.
  • -Bno-symbolic — this option can cancel previously specified -Bsymbolic and -Bsymbolic-functions. It’s the “jk bestie” option 😭.
  • --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. Data girlies, this one’s for you ✨.
  • --dynamic-list-cpp-new — provide the builtin dynamic list for C++ operator new and delete. It is mainly useful for building shared libstdc++. Very C++ core 👑
  • --dynamic-list-cpp-typeinfo — provide the builtin dynamic list for C++ runtime type identification. RTTI bestie, periodt 💅.
  • --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 inside ELF dynamic libraries mentioned on the command line. Normally the linker won't add a DT_NEEDED tag to the output binary for each library mentioned in a DT_NEEDED tag in an input dynamic library. With --copy-dt-needed-entries specified on the command line however any dynamic libraries that follow it will have their DT_NEEDED entries added. The default behaviour can be restored with --no-copy-dt-needed-entries.

This option also has an effect on the resolution of symbols in dynamic libraries. With --copy-dt-needed-entries 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 the default setting 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. If the symbol is defined as a common value then any files where this happens appear next. Finally any files that reference the symbol are listed. Very organized, very demure 🎀.

  • --ctf-variables, --no-ctf-variables — the CTF debuginfo format supports a section which encodes the names and types of variables found in the program which do not appear in any symbol table. These variables clearly cannot be looked up by address by conventional debuggers, so the space used for their types and names is usually wasted: the types are usually small but the names are often not. --ctf-variables causes the generation of such a section. The default behaviour can be restored with --no-ctf-variables. CTF girlies know 😭.
  • --ctf-share-types=method — adjust the method used to share types between translation units in CTF.
    • share-unconflicted — put all types that do not have ambiguous definitions into the shared dictionary, where debuggers can easily access them, even if they only occur in one translation unit. This is the default. Slay.
    • share-duplicated — put only types that occur in multiple translation units into the shared dictionary: types with only one definition go into per-translation-unit dictionaries. Types with ambiguous definitions in multiple translation units always go into per-translation-unit dictionaries. This tends to make the CTF larger, but may reduce the amount of CTF in the shared dictionary. For very large projects this may speed up opening the CTF and save memory in the CTF consumer at runtime. Highkey a tradeoff 💀.
  • --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. No duplicate drama, periodt 💅.

  • --force-group-allocation — this option causes the linker to place section group members like normal input sections, and to delete the section groups. This is the default behaviour for a final link but this option can be used to change the behaviour of a relocatable link (-r). The script command FORCE_GROUP_ALLOCATION has the same effect. Group chat but make it linker ✨.
  • --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.

The linker processes --defsym arguments and -T arguments in order, placing --defsym before -T will define the symbol before the linker script from -T is processed, while placing --defsym after -T will define the symbol after the linker script has been processed. This difference has consequences for expressions within the linker script that use the --defsym symbols, which order is correct will depend on what you are trying to achieve. Order matters bestie, fr fr 🌸.

  • --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. Readable names are the main character energy we deserve 👑.
  • -Ifile, --dynamic-linker=file — set the name of the dynamic linker. This is only meaningful when generating dynamically linked ELF executables. The default dynamic linker is normally correct; don't use this unless you know what you are doing. Like, genuinely, don't touch unless you’re that girl 💅.
  • --no-dynamic-linker — when producing an executable file, omit the request for a dynamic linker to be used at load-time. This is only meaningful for ELF executables that contain dynamic relocations, and usually requires entry point code that is capable of processing these relocations. Big brain move, ngl 🧚.
  • --embedded-relocs — this option is similar to the --emit-relocs option except that the relocs are stored in a target-specific section. This option is only supported by the BFIN, CR16 and M68K targets. Niche and iconic 💜.
  • --disable-multiple-abs-defs — do not allow multiple definitions with symbols included in filename invoked by -R or --just-symbols. Sorry bestie, one definition only 🙈.
  • --fatal-warnings, --no-fatal-warnings — treat all warnings as errors. The default behaviour can be restored with the option --no-fatal-warnings. So dramatic, but honestly fair 🔥.
  • -w, --no-warnings — the "shhh bestie" flag 💀 do not display any warning or error messages, at all. This overrides --fatal-warnings if it has been enabled. You'd use this when you know the output binary will not work, but there is still a need to create it. Chaotic? Yes. Sometimes necessary? Also yes. 🙈
  • --force-exe-suffix — makes sure 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. It's giving "Windows please just run my file" energy 🪟, and it's useful when you're 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. Periodt.

  • --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. Heads up: garbage collection for COFF and PE format targets is supported, but the implementation is currently considered to be experimental. 👀

--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, --undefined, and --gc-keep-exported.

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

As a GNU extension, ELF input sections marked with the "SHF_GNU_RETAIN" flag will not be garbage collected. 🛡️

  • --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. Receipts for everything the linker yeeted 🗑️💅
  • --gc-keep-exported — when --gc-sections is enabled, this option prevents garbage collection of unused input sections that contain global symbols having default or protected visibility. It's intended to be used for executables where unreferenced sections would otherwise be garbage collected regardless of the external visibility of contained symbols. Note that this option has no effect when linking shared objects, since it is already the default behaviour. This option is only supported for ELF format targets. 👑
  • --print-output-format — print the name of the default output format (perhaps influenced by other command-line options). This is the string that would appear in an "OUTPUT_FORMAT" linker script command. Manifesting the format ✨
  • --print-memory-usage — print used size, total size and used size of memory regions created with the MEMORY command. This is useful on embedded targets to have a quick view of amount of free memory. The format of the output has one headline and one line per region. It is both human readable and easily parsable by tools. Here's what an output looks like:
        Memory region         Used Size  Region Size  %age Used
                     ROM:        256 KB         1 MB     25.00%
                     RAM:          32 B         2 GB      0.00%

Note: if you want to find out about the memory usage of the linker itself, then the --stats option will do this. Not the same thing, bestie — don't get it twisted 💅

  • --help — print a summary of the command-line options on the standard output and exit. Your lil cheat sheet 🎀
  • --target-help — print a summary of all target-specific options on the standard output and exit. Same vibe, but for the target-specific stuff 🌸
  • -Map=mapfile — print a link map to the file mapfile. See the description of the -M option, above. If mapfile is just the character - then the map will be written to stdout.

Specifying a directory as mapfile causes the linker map to be written as a file inside the directory. Normally the name of the file inside the directory is computed as the basename of the output file with .map appended. If however the special character % is used, then this will be replaced by the full path of the output file. Additionally, if there are any characters after the % symbol, then .map will no longer be appended.

-o foo.exe -Map=bar                  [Creates ./bar]
-o ../dir/foo.exe -Map=bar           [Creates ./bar]
-o foo.exe -Map=../dir               [Creates ../dir/foo.exe.map]
-o ../dir2/foo.exe -Map=../dir       [Creates ../dir/foo.exe.map]
-o foo.exe -Map=%                    [Creates ./foo.exe.map]
-o ../dir/foo.exe -Map=%             [Creates ../dir/foo.exe.map]
-o foo.exe -Map=%.bar                [Creates ./foo.exe.bar]
-o ../dir/foo.exe -Map=%.bar         [Creates ../dir/foo.exe.bar]
-o ../dir2/foo.exe -Map=../dir/%     [Creates ../dir/../dir2/foo.exe.map]
-o ../dir2/foo.exe -Map=../dir/%.bar [Creates ../dir/../dir2/foo.exe.bar]

It is an error to specify more than one % character. 🚨

If the map file already exists then it will be overwritten by this operation. No take-backs, no warnings, just gone 💀
  • --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. Trade-off era 😮‍💨
  • --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.

The effects of this option can be reverted by using -z undefs. Undo button, iconic 🔄

  • --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. First come, first served fr fr 👑
  • --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.

  • --error-handling-script=scriptname — if this option is provided, then the linker will invoke scriptname whenever an error is encountered. Currently however only two kinds of error are supported: missing symbols and missing libraries. Two arguments will be passed to script: the keyword "undefined-symbol" or `missing-lib" and the name of the undefined symbol or missing library. The intention is that the script will provide suggestions to the user as to where the symbol or library might be found. After the script has finished, then the normal linker error message will be displayed. Little helper script bestie 🫶
The availability of this option is controlled by a configure time switch, so it may not be present in specific implementations. Check before you rely on it!
  • --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. No more silent ignoring 🙅‍♀️
  • --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. The matching set, we love symmetry ✨
  • --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. Don't just slap it on and hope, bestie 😭
  • --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. On/off switch behaviour, very demure 💅
  • --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. This flag is basically "no, keep it, I can fix it" 🩹
  • -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. Command line only, no side quests 🚫📜
  • --oformat=output-format — so like, ld can be built to handle more than one kind of object file, right? And if yours is one of those fancy multi-format builds, this option lets you pick the binary format for the output object file. But honestly bestie, even when ld supports alternatives, you usually don't need to touch this — ld is configured to default to 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 set the output format, but this option overrides it. Slay.
  • --out-implib file — makes an import library in file corresponding to the executable the linker is generating (like a DLL or an ELF program, iykyk). This import library (which should be called "*.dll.a" or "*.a" for DLLs) may be used to link clients against the generated executable. The way this slays is that you get to skip a separate import library creation step (eg. "dlltool" for DLLs). 🎀 Heads up though: this option is only available for the i386 PE and ELF targetted ports of the linker.
  • -pie, --pic-executable — creates a position independent executable. Currently only supported on ELF platforms, no cap. Position independent executables get relocated by the dynamic linker to the virtual address the OS chooses for them, which can vary between invocations. They're marked ET_DYN in the ELF file header, but they differ from shared libraries in a number of ways. In particular, defined symbols in a PIE by default can not be overridden by another object the way they can be in a shared library. 👑
  • -no-pie — creates a position dependent executable. This is the default. Periodt.
  • -qmagic — this option is ignored for Linux compatibility. 🙈
  • -Qy — this option is ignored for SVR4 compatibility. Also just vibing in the void.
  • --relax, --no-relax — an option with machine dependent effects, bestie. Only supported on a few targets, so don't come for it if your platform isn't on the list.

On some platforms the --relax option performs target specific, global optimizations that become possible when the linker resolves addressing in the program — like relaxing address modes, synthesizing new instructions, selecting shorter version of current instructions, and combining constant values. ✨

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. 💀 So like, pick your fighter.

On platforms where the feature is supported, the option --no-relax will disable it.

On platforms where the feature is not supported, both --relax and --no-relax are accepted, but ignored. They're just there for the vibes.

  • --retain-symbols-file=filename — retains 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. Protect them at all costs.

You may only specify --retain-symbols-file once in the command line. It overrides -s and -S.

  • -rpath=dir — adds 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. Searching -rpath in this way is only supported by native linkers and cross linkers which have been configured with the --with-sysroot 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. She's the backup plan. 💜

The -rpath option may also be used on SunOS. By default, on SunOS, the linker will form a runtime search path 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, several directories are searched as described below. The -rpath-link option specifies the first set of directories to search. This option may specify a sequence of directory names either by providing a list of names separated by colons, or by appearing multiple times.

The tokens $ORIGIN and $LIB can appear in these search directories. They will be replaced by the full path to the directory containing the program or shared object in the case of $ORIGIN, and either lib — for 32-bit binaries — or lib64 — for 64-bit binaries — in the case of $LIB.

The alternative form of these tokens — ${ORIGIN} and ${LIB} — can also be used. The token $PLATFORM is not supported. 🙅

The --rpath-link 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 unintentionally use a different search path than the runtime linker would have used. Bestie, be careful, fr fr. ⚠️

When additional shared libraries are required, the linker will search directories in the order listed below in order to find them. Note however that this only applies to additional libraries needed to satisfy already included shared libraries. It does not apply to libraries that are included via the -l command line option. Searches for -l libraries are only conducted in directories specified by the -L option.

  1. Any directories specified by -rpath-link options.
  2. Any directories specified by -rpath options. The difference between -rpath and -rpath-link is that directories specified by -rpath options are included in the executable and used at runtime, whereas the -rpath-link option is only effective at link time. Searching -rpath in this way is only supported by native linkers and cross linkers which have been configured with the --with-sysroot option.
  3. On an ELF system, for native linkers, if the -rpath and -rpath-link options were not used, search the contents of the environment variable "LD_RUN_PATH".
  4. On SunOS, if the -rpath option was not used, search any directories specified using -L options.
  5. For a native linker, search the contents of the environment variable "LD_LIBRARY_PATH".
  6. For a native ELF linker, the directories in "DT_RUNPATH" or "DT_RPATH" of a shared library are searched for shared libraries needed by it. The "DT_RPATH" entries are ignored if "DT_RUNPATH" entries exist.
  7. For a linker for a Linux system, if the file /etc/ld.so.conf exists, the list of directories found in that file. Note: the path to this file is prefixed with the "sysroot" value, if that is defined, and then any "prefix" string if the linker was configured with the --prefix=<path> option.
  8. For a native linker on a FreeBSD system, any directories specified by the "_PATH_ELF_HINTS" macro defined in the elf-hints.h header file.
  9. Any directories specified by a "SEARCH_DIR" command in a linker script given on the command line, including scripts specified by -T (but not -dT).
  10. The default directories, normally /lib and /usr/lib.
  11. Any directories specified by a plugin LDPT_SET_EXTRA_LIBRARY_PATH.
  12. Any directories specified by a "SEARCH_DIR" command in a default linker script.

Note however on Linux based systems there is an additional caveat: If the --as-needed option is active and a shared library is located which would normally satisfy the search and this library does not have DT_NEEDED tag for libc.so and there is a shared library later on in the set of search directories which also satisfies the search and this second shared library does have a DT_NEEDED tag for libc.so then the second library will be selected instead of the first. Sneaky little plot twist, honestly. 😭

If the required shared library is not found, the linker will issue a warning and continue with the link. She's resilient like that. 💅

  • --section-ordering-file=script — this option is used to augment the current linker script with additional mapping of input sections to output sections. This file must use the same syntax for "SECTIONS" as is used in normal linker scripts, but it should not do anything other than place input sections into output sections. @pxref{SECTIONS}

A second constraint on the section ordering script is that it can only reference output sections that are already defined by whichever linker script is currently in use. (Ie the default linker script or a script specified on the command line). The benefit of the section ordering script however is that the input sections are mapped to the start of the output sections, so that they can ensure the ordering of sections in the output section. For example, imagine that the default linker script looks like this:

        SECTIONS {
          .text : { *(.text.hot) ; *(.text .text.*) }
          .data : { *(.data.big) ; *(.data .data.*) }
          }

Then if a section ordering file like this is used:

          .text : { *(.text.first) ; *(.text.z*) }
          .data : { foo.o(.data.first) ; *(.data.small) }

This would be equivalent to a linker script like this:

SECTIONS {
  .text : { *(.text.first) ; *(.text.z*) ; *(.text.hot) ; *(.text .text.*) }
  .data : { foo.o(.data.first) ; *(.data.small) ; *(.data.big) ; *(.data .data.*) }
  }

The whole point of the section ordering file, bestie, is that it lets you order the sections you actually care about without having to stress about literally any other section, or memory regions, or anything else in the universe. So chill. 💅

  • -shared, -Bshareable — okay so this one makes a shared library ✨. Right now it's only supported on ELF, XCOFF and SunOS platforms. And on SunOS? The linker will just automatically create a shared library if the -e option isn't used and there are undefined symbols in the link. Not me doing it for you. 😌
  • --sort-common, --sort-common=ascending, --sort-common=descending — tells ld to sort the common symbols by alignment, in ascending or descending order, when it places them into the appropriate output sections. The alignments it considers are: sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-byte. Why? To prevent gaps between symbols due to alignment constraints, periodt. And if you don't specify a sorting order, descending is just assumed. 🎀
  • --sort-section=name — this one applies "SORT_BY_NAME" to all wildcard section patterns in the linker script. iconic.
  • --sort-section=alignment — and this one applies "SORT_BY_ALIGNMENT" to all wildcard section patterns in the linker script. 💖
  • --spare-dynamic-tags=count — specifies the number of empty slots to leave in the .dynamic section of ELF shared objects. Empty slots might be needed by post processing tools, like the prelinker. The default is 5.
  • --split-by-file[=size] — similar to --split-by-reloc but it creates a new output section for each input file when size is reached. And size defaults to a size of 1 if you don't give it one. 🦋
  • --split-by-reloc[=count] — tries to create extra sections in the output file so that no single output section in the file contains more than count relocations. Super useful when generating huge relocatable files for downloading into certain real time kernels with the COFF object file format — because COFF cannot represent more than 65535 relocations in a single section. 😭 Note that this will fail to work with object file formats that don't support arbitrary sections. Also 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 just contain that many relocations. count defaults to a value of 32768.
  • --stats[=filename] — compute and display statistics about the operation of the linker, like execution time and memory usage. 📊

If the optional filename argument isn't supplied, then only basic information is reported, and it goes to the standard error output stream. If filename is supplied, then extended information is written to that named file. If filename is set to just the - symbol, then the extended information goes to the standard output stream. And if filename starts with + then the file is opened in append mode rather than overwrite mode. ✨

If the -Map option has been enabled then the information is also recorded in the map file as well. Note: if both the --stats option and the -Map options have been given filename arguments and they match, then the information will only be written out once, not twice. 🙅‍♀️

If the LD_STATS environment variable is defined then this behaves like the --stats option. If the variable's value is a string, then it'll be used as the name of a file into which the information should be recorded. Otherwise the information goes to the standard output stream. Using the environment variable lets you record stats without having to alter the linker's command line. Note: if both the environment variable and the --stats option are used, then the --stats option takes precedence. 👑

The extended information reported includes the cpu time used and, if the getrusage() system library call is available, then maximum set size and the user and system run times as well. In addition, if the mallinfo or mallinfo2 system library calls are available, then the total memory usage is reported. 🧚

The information is displayed for individual parts of the linking process which are referred to as phases. Note that individual phases can contain or overlap with each other, so you should not assume that the overall resources used by the linker is the sum of the resources used by the individual phases. 💀

In addition the information is also reported for a special phase called ALL which covers the entire linking process.

When extended information is being reported, the linker version, command line arguments and linker start time are also included. This makes it easier to handle the situation where multiple links are being invoked by a build system, and to identify exactly which arguments were responsible for producing the statistics that are reported. 🕵️‍♀️

The extended output looks something like this:

Stats: linker version: (GNU Binutils) 2.44.50.20250401
Stats: linker started: Wed Apr  2 09:36:41 2025
Stats: args: ld -z norelro -z nomemory-seal -z no-separate-code -o a.out [...]

Stats: phase               cpu time       rss      user time    system time     memory
Stats: name                (microsec)   (KiB)      (seconds)      (seconds)      (KiB)
Stats: ALL                   390082    217740              0              0   25219440
Stats: ctf processing            12         0              0              0          0
Stats: string merge            1324         0              0              0     406544
Stats: parsing                  349       288              0              0     119792
Stats: plugins                    1         0              0              0          0
Stats: processing files      259616    214524              0              0   31569120
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  • --no-stats — disables the reporting of usage statistics, should it have been enabled via the --stats command line option or the LD_STATS environment variable. bye bye stats 🫶
  • --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. 🌸
  • --task-link — this is used by COFF/PE based targets to create a task-linked object file where all of the global symbols have been converted to statics. 🎀
  • --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 cannot read the resulting program ("gdb" has no trouble, bestie, it's fine). 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 can 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. ⚠️
  • --image-base=org — when using ELF, same as -Ttext-segment, with both options effectively setting the base address of the ELF executable. 🔥

When using PE, 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. ✨

  • -Tbss=org, -Tdata=org, -Ttext=org — same as --section-start, with ".bss", ".data" or ".text" as the sectionname. 🦋
  • -Ttext-segment=org — when creating an ELF executable, it will set the address of the first byte of the first segment. Note that when -pie is used with -Ttext-segment=org, the output executable is marked ET_EXEC so that the address of the first byte of the text segment will be guaranteed to be org at run time. 💅
  • -Trodata-segment=org — when creating an ELF executable or shared object for a target where the read-only data is in its own segment separate from the executable text, it will set the address of the first byte of the read-only data segment. 💜
  • -Tldata-segment=org — when creating an ELF executable or shared object for x86-64 medium memory model, it will set the address of the first byte of the ldata segment. ⭐
  • --unresolved-symbols=method — determine how to handle unresolved symbols. There are four possible values for method: 👀
    • ignore-all — do not report any unresolved symbols. 🙈
    • report-all — report all unresolved symbols. This is the default.
    • ignore-in-object-files — report unresolved symbols that are contained in shared libraries, but ignore them if they come from regular object files.
    • ignore-in-shared-libs — report unresolved symbols that come from regular object files, but ignore them if they come from shared libraries. This can be useful when creating a dynamic binary and it's 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[=NUMBER] — okay so these two are besties 💖 they make ld spill the tea: it shows you the version number for ld and lists out the linker emulations it supports 🎀. It also tells you which input files can and can't be opened 🙈, and shows you the linker script the linker is actually using ✨. And if the optional NUMBER argument is > 1, you also get plugin symbol status displayed 💅. Very demure, very informative.
  • --version-script=version-scriptfile — names the version script you want to hand the linker 📜. Normally you'd use this while making shared libraries, so you can add extra info about the version hierarchy of the library you're building 💖. Heads up though: this is only fully supported on ELF platforms that support shared libraries — go peek at VERSION for that 🦋. On PE platforms it's partially supported: they can use version scripts to filter symbol visibility in auto-export mode, meaning any symbols marked local in the version script won't get exported 🚫. Periodt.
  • --warn-common — warns you whenever a common symbol gets combined with another common symbol, or with a symbol definition 👀. Unix linkers are fine with this kinda sloppy practice, but linkers on some other operating systems are not 💀. This option is your little detective for finding potential problems from combining global symbols 🕵️‍♀️. Lowkey downside: some C libraries do this practice, so you might catch warnings about symbols inside the libraries too, not just your own program 😭.

There are three kinds of global symbols, and here they are illustrated with 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 has to 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 🧚, and if they're different sizes, it picks the largest size 💪. The linker also turns a common symbol into a declaration if there's a definition of the same variable.

The --warn-common option can produce five kinds of warnings 🔥. Each warning is 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
  1. 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 the symbols are encountered in a different order.
<file>(<section>): warning: definition of `<symbol>'
   overriding common
<file>(<section>): warning: common is here
  1. 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
  1. 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
  1. Merging a common symbol with a previous smaller common symbol 🌸. This is the same as the previous case, except 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 — warns you if any global constructors are used 👀. Ngl this is only useful for a few object file formats. For formats like COFF or ELF, the linker literally can't detect the use of global constructors 🙈. It's giving "limited edition".
  • --warn-execstack, --warn-execstack-objects, --no-warn-execstack — on ELF platforms, the linker may throw warning messages at you if it's asked to create an output file that contains an executable stack 💀. There are three possible states:
    1. Do not generate any warnings 🤐.
    2. Always generate warnings, even if the executable stack is requested via the -z execstack command line option 🗣️.
    3. Only generate a warning if an object file requests an executable stack, but not if the -z execstack option is used 🙃.

The default state depends on how the linker was configured when it was built 🏗️. The --no-warn-execstack option always puts the linker into the no-warnings state. The --warn-execstack option puts the linker into the warn-always state. The --warn-execstack-objects option puts the linker into the warn-for-object-files-only state 💅.

Note: ELF format input files can specify that they need an executable stack by having a .note.GNU-stack section with the executable bit set in its section flags ✨. They can specify that they do not need an executable stack by having the same section, but without the executable flag bit set 🚫. If an input file does not have a .note.GNU-stack section, then the default behaviour is target specific 👀. For some targets, the absence of such a section implies that an executable stack is required. This is often a problem for hand crafted assembler files 😭.
  • --error-execstack, --no-error-execstack — if the linker is going to generate a warning message about an executable stack, then --error-execstack will instead change that warning into an error 💥. But note — this option does not change the linker's execstack warning generation state 🙅‍♀️. Use --warn-execstack or --warn-execstack-objects to set a specific warning state, bestie.

The --no-error-execstack option restores the default behaviour of generating warning messages 🫶.

  • --warn-multiple-gp — warns you if multiple global pointer values are required in the output file 👀. This is only meaningful for certain processors, like the Alpha 🌈. Specifically, some processors put large-valued constants in a special section, and a special register (the global pointer) points into the middle of this section, so 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 🥲. So in large programs, it's often necessary to use multiple global pointer values in order to address all possible constants. This option makes a warning get issued whenever this case occurs 💅.
  • --warn-once — only warns once for each undefined symbol, instead of once per module that refers to it 🙌. Your terminal will thank you.
  • --warn-rwx-segments, --no-warn-rwx-segments — warns you if the linker creates a loadable, non-zero sized segment that has all three of the read, write and execute permission flags set 💀. That kind of segment represents a potential security vulnerability, no cap. On top of that, warnings get generated if a thread local storage segment is created with the execute permission flag set, regardless of whether or not it has the read and/or write flags set 😭.

These warnings are enabled by default ✨. You can disable them with --no-warn-rwx-segments and re-enable them with --warn-rwx-segments 🎀.

  • --error-rwx-segments, --no-error-rwx-segments — if the linker is going to generate a warning message about an executable, writeable segment, or an executable TLS segment, then --error-rwx-segments turns that warning into an error instead 💥. The --no-error-rwx-segments option restores the default behaviour of just generating a warning message 🫶.
Note — the --error-rwx-segments option does not by itself turn on warnings about these segments 🙅‍♀️. Those warnings are either enabled by default (if the linker was configured that way) or via the --warn-rwx-segments command line option.
  • --warn-section-align — warns you if the address of an output section is changed because of alignment 👀. Typically the alignment gets set by an input section. The address will only be changed if it's not explicitly specified — that is, if the "SECTIONS" command doesn't specify a start address for the section 🌸.
  • --warn-textrel — warns you if the linker adds DT_TEXTREL to a position-independent executable or shared object 👑.
  • --warn-alternate-em — warns you if an object has alternate ELF machine code 🦋.
  • --warn-unresolved-symbols — if the linker is going to report an unresolved symbol (see the option --unresolved-symbols), it will normally generate an error 😤. This option makes it generate a warning instead 🫶.
  • --error-unresolved-symbols — this restores the linker's default behaviour of generating errors when it's 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 — uses 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 literally every call to malloc gets rerouted to the function __wrap_malloc instead. And then the call to __real_malloc inside __wrap_malloc is the one that reaches the actual malloc. 💫

You might also wanna provide a __real_malloc function of your own, so that links without the --wrap option still succeed. But if you do, bestie, do not put the definition of __real_malloc in the same file as __wrap_malloc — because if you do, the assembler may resolve the call before the linker even gets a chance to wrap it to malloc. 😭

Also important: only undefined references get replaced by the linker. So translation-unit-internal references to a symbol do not get resolved to __wrap_symbol. In the next example, the call to f inside g is not resolved to __wrap_f. Fr fr.

int
f (void)
{
  return 123;
}

int
g (void)
{
  return f();
}
  • --eh-frame-hdr, --no-eh-frame-hdr — ask for (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the creation of the .eh_frame_hdr section and the ELF PT_GNU_EH_FRAME segment header. ✨
  • --no-ld-generated-unwind-info — request creation of .eh_frame unwind info for linker-generated code sections like PLT. This one is on by default if linker-generated unwind info is supported. 🎀
  • --discard-sframe — throw away .sframe stack trace info from the output. This also prohibits the creation of SFrame stack trace data for linker-generated code sections like PLT. Off by default. 🗑️
  • --enable-new-dtags, --disable-new-dtags — this linker can create the new dynamic tags in ELF, but older ELF systems might not understand them. 👀 If you specify --enable-new-dtags, the new dynamic tags get created as needed and older dynamic tags get omitted. If you specify --disable-new-dtags, no new dynamic tags get created. By default the new dynamic tags are not created. Heads up: these 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. Cranking this value up can reduce how long the linker takes to do its thing, at the cost of more memory. Lowering it does the reverse — less memory, slower. Default is 4051 under normal circumstances, and 1021 if the --reduce-memory-overheads command line option is used. 🔢
  • --hash-style=style — set the type of the linker's hash table(s). style can be sysv for the classic ELF .hash section, gnu for the new-style GNU .gnu.hash section, or both for both the classic ELF .hash and the new-style GNU .gnu.hash hash tables. The default depends on how the linker was configured, but for most Linux-based systems it'll be both. 💅
  • --compress-debug-sections=none, --compress-debug-sections=zlib, --compress-debug-sections=zlib-gnu, --compress-debug-sections=zlib-gabi, --compress-debug-sections=zstd — on ELF platforms, these control how DWARF debug sections get compressed using zlib.
    • --compress-debug-sections=none doesn't compress DWARF debug sections at all.
    • --compress-debug-sections=zlib-gnu compresses DWARF debug sections and renames them to begin with .zdebug instead of .debug.
    • --compress-debug-sections=zlib-gabi also compresses DWARF debug sections, but instead of renaming them it sets the SHF_COMPRESSED flag in the sections' headers.
    • --compress-debug-sections=zlib is an alias for --compress-debug-sections=zlib-gabi.
    • --compress-debug-sections=zstd compresses DWARF debug sections using zstd. 🗜️
Note: this option overrides any compression in input debug sections. So if a binary is linked with --compress-debug-sections=none, for example, then any compressed debug sections in input files will be uncompressed before they're copied into the output binary. 😳

The default compression behaviour varies depending on the target involved and the configure options used to build the toolchain. You can figure out the default by examining the output from the linker's --help option.

  • --reduce-memory-overheads — 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 this switch is setting 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 if the --hash-size switch has been used, though.

The --reduce-memory-overheads switch may also be used to enable other tradeoffs in future versions of the linker. 🔮

  • --max-cache-size=size — ld normally caches the relocation information and symbol tables of input files in memory with unlimited size. This option sets the maximum cache size to size. Note: if the --no-keep-memory command line option has been used, then the linker acts as if the maximum cache size has been set to 0 — i.e. nothing is retained. 🧠
  • --build-id, --build-id=style — request the creation of a .note.gnu.build-id ELF note section or a .buildid COFF section. The contents of the note are unique bits identifying this linked file. ✨ style can be:
    • uuid — use 128 random bits
    • sha1 — use a 160-bit SHA1 hash
    • md5 — use a 128-bit MD5 hash
    • xx — use a 128-bit XXHASH on the normative parts of the output contents
    • 0xhexstring — use a chosen bit string specified as an even number of hexadecimal digits (- and : characters between digit pairs are ignored)

If style is omitted, sha1 is used.

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

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

  • --package-metadata=JSON — request the creation of a .note.package ELF note section. The contents of the note are in JSON format, as per the package metadata specification. For more info see: https://systemd.io/ELF_PACKAGE_METADATA/ 📦

The JSON argument supports percent-encoding and the following %[string] encoding (where string refers to the name in HTML's Named Character References): %[comma] for ,, %[lbrace] for {, %[quot] for ", %[rbrace] for }, and %[space] for the space character.

If the JSON argument is missing/empty then this disables the creation of the metadata note, if one had been enabled by an earlier occurrence of the --package-metadata option. And if the linker was built with libjansson, then the JSON string will be validated. ✅

🦋 the i386 PE linker era 🦋

The i386 PE linker supports the -shared option, which makes the output a dynamically linked library (DLL) instead of a normal executable. You should name the output *.dll when you use this option, bestie, okay? 💖

On top of that, 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 make sure they get linked in, just like a normal object file. iykyk.)

In addition to the options common to all targets, the i386 PE linker supports extra command-line options specific to the i386 PE target. Options that take values may be separated from their values by either a space or an equals sign. 🎀

  • --add-stdcall-alias — if given, symbols with a stdcall suffix (@nn) will be exported as-is and also with the suffix stripped. [This option is specific to the i386 PE targeted port of the linker] ✨
  • --base-file file — use file as the name of a file in which to save the base addresses of all the relocations needed for generating DLLs with dlltool. [This is an i386 PE specific option] 📁
  • --dll — create a DLL instead of a regular executable. You may also use -shared or specify a LIBRARY in a given .def file. [This option is specific to the i386 PE targeted port of the linker] 🏗️
  • --enable-long-section-names, --disable-long-section-names — the PE variants of the COFF object format add an extension that permits the use of section names longer than eight characters, the normal limit for COFF. By default these names are only allowed in object files, since fully-linked executable images don't carry the COFF string table required to support the longer names. As a GNU extension, it's possible to allow their use in executable images as well, or to (probably pointlessly!) disallow it in object files, by using these two options. 😅

Executable images generated with these long section names are slightly non-standard, carrying as they do a string table, and may generate confusing output when examined with non-GNU PE-aware tools, such as file viewers and dumpers. However, GDB relies on the use of PE long section names to find Dwarf-2 debug information sections in an executable image at runtime. So if neither option is specified on the command-line, ld will enable long section names — overriding the default and technically correct behaviour — when it finds the presence of debug information while linking an executable image and not stripping symbols. 🔍 [This option is valid for all PE targeted ports of the linker]

  • --enable-stdcall-fixup, --disable-stdcall-fixup — okay so imagine the link hits a symbol it literally cannot resolve. Bestie, it does NOT just give up — it goes "fuzzy linking" mode and hunts for another defined symbol that's identical except for the name format (cdecl vs stdcall), then resolves by linking to that match. Like the undefined _foo could get linked to the function _foo@12, or the undefined _bar@16 might link to _bar. When it pulls this off it prints a warning, because normally it should have just failed to link — but sometimes import libraries made from third-party dlls need this to even be usable. Pass --enable-stdcall-fixup and the feature is fully on and the warnings go quiet 💅. Pass --disable-stdcall-fixup and it's off, so mismatches like that are straight-up errors. [This option is specific to the i386 PE targeted port of the linker]
  • --leading-underscore, --no-leading-underscore — for most targets the default symbol-prefix is an underscore, and it's defined in the target's description. This option lets you disable/enable that default underscore symbol-prefix. 🎀
  • --export-all-symbols — give this one and every global symbol in the objects used to build a DLL gets exported by the DLL. ✨ Note that this is the default if there otherwise wouldn't be any exported symbols. But 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. Also note the symbols "DllMain@12", "DllEntryPoint@0", "DllMainCRTStartup@12", and "impure_ptr" will <em>not</em> be automatically exported. And symbols imported from other DLLs won't be re-exported, nor will symbols specifying the DLL's internal layout such as those beginning with "_head_" or ending with "_iname". On top of that, no symbols from "libgcc", "libstd++", "libmingw32", or "crtX.o" will be exported. Symbols whose names begin with "__rtti_" or "__builtin_" won't be exported either, to help with C++ DLLs. And finally there's an extensive list of cygwin-private symbols that aren't exported (obviously, this applies only 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,... — hands you a lil list of symbols that should NOT be automatically exported 🙈. The symbol names can be delimited by commas or colons. [This option is specific to the i386 PE targeted port of the linker]
  • --exclude-all-symbols — says nope, no symbols should be automatically exported. Periodt. [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 that are multiples of this number. Defaults to 512. [This option is specific to the i386 PE targeted port of the linker]
  • --heap reserve, --heap reserve,commit — set the number of bytes of memory to reserve (and optionally commit) to be used as heap for this program 🫶. The default is 1MB reserved, 4K committed. [This option is specific to the i386 PE targeted port of the linker]
  • --kill-at — given this one, the stdcall suffixes (@nn) get stripped from symbols before they're exported ✂️. [This option is specific to the i386 PE targeted port of the linker]
  • --large-address-aware — given this, 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 together with the /3GB or /USERVA=value megabytes switch in the "[operating systems]" section of the BOOT.INI. Otherwise this bit has <em>no effect</em>. [This option is specific to PE targeted ports of the linker]
  • --disable-large-address-aware — undoes the effect of a previous --large-address-aware option 💀. This is useful if --large-address-aware is always set by the compiler driver (e.g. Cygwin gcc) and the executable does not support virtual addresses greater than 2 gigabytes. [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]
  • --enable-auto-image-base, --enable-auto-image-base= value — automatically choose the image base for DLLs, optionally starting with base value, 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 that 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's 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 — does sophisticated linking of "_symbol" to "__imp__symbol" for DATA imports from DLLs, which makes it possible to bypass the dllimport mechanism on the user side and to reference unmangled symbol names 🌈. [This option is specific to the i386 PE targeted port of the linker]

The following remarks pertain to the original implementation of the feature and are <em>obsolete nowadays</em> for Cygwin and MinGW targets. 💀

Note: Use of the 'auto-import' extension will cause the text section of the image file to be made writable. This does <em>not</em> conform to the PE-COFF format specification published by Microsoft.
Note — use of the 'auto-import' extension will also cause read only data which would normally be placed into the .rdata section to be placed into the .data section instead. This is in order to work around a problem with consts that is described here: http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html

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

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

This message occurs when some (sub)expression accesses an address ultimately given by the sum of <em>two</em> 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 }

okay so bestie, there's a third way to deal with this whole 'direct address with constant offset' mess 💅 — you just abandon 'auto-import' for the offending symbol and slap it with __declspec(dllimport). Sounds cute, right? Wrong. 😭 In practice that means you're stuck using compile-time #defines to tell the code whether you're building a DLL, building client code that'll link to the DLL, or just building/linking to a static library. And when you're picking between all these ways to solve the problem, please consider typical real-world usage, bestie:

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]);
}

And a fourth way to dodge this whole problem? Just re-code your library so it uses a functional interface instead of a data interface for the offending variables — like set_foo() and get_foo() accessor functions. iconic behavior, honestly 🫶

  • --disable-auto-import — nope, don't even try to do the 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 has expressions like the ones described in the --enable-auto-import section (aka DATA imports from a DLL with non-zero offset), this switch creates a vector of 'runtime pseudo relocations' that the runtime environment can use 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 option is specific to the i386 PE targeted port of the linker]
  • --enable-extra-pe-debug — show extra 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 that are a multiple of this number. Defaults to 0x1000. [This option is specific to the i386 PE targeted port of the linker]
  • --stack reserve
  • --stack reserve,commit — specify the number of bytes of memory to reserve (and optionally commit) to be used as the stack for this program. 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 your program will run under. The legal values for which are "native", "windows", "console", "posix", and "xbox". You can optionally set the subsystem version too. Numeric values are also accepted for which. [This option is specific to the i386 PE targeted port of the linker]

✨ the DllCharacteristics squad ✨

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

  • --high-entropy-va
  • --disable-high-entropy-va — the image is compatible with 64-bit address space layout randomization (ASLR). Enabled by default for 64-bit PE images in MinGW targets. 👑 Also: this option implies --dynamicbase and --enable-reloc-section.
  • --dynamicbase
  • --disable-dynamicbase — the image base address may be relocated using address space layout randomization (ASLR). Introduced with MS Windows Vista for i386 PE targets. Enabled by default for MinGW targets, but you can turn it off with --disable-dynamicbase. This one also implies --enable-reloc-section.
  • --forceinteg
  • --disable-forceinteg — code integrity checks are enforced. Disabled by default.
  • --nxcompat
  • --disable-nxcompat — the image is compatible with Data Execution Prevention. Introduced with MS Windows XP SP2 for i386 PE targets. Enabled by default for MinGW targets.
  • --no-isolation
  • --disable-no-isolation — even though the image understands isolation, don't isolate the image. Disabled by default.
  • --no-seh
  • --disable-no-seh — the image doesn't use SEH. No SE handler may be called from this image. Disabled by default.
  • --no-bind
  • --disable-no-bind — do not bind this image. Disabled by default.
  • --wdmdriver
  • --disable-wdmdriver — the driver uses the MS Windows Driver Model. Disabled by default.
  • --tsaware
  • --disable-tsaware — the image is Terminal Server aware. Disabled by default.
  • --insert-timestamp
  • --no-insert-timestamp — insert a real timestamp into the image. This is the default behaviour, since it matches legacy code and means the image will work with other, proprietary tools. 🙈 The problem with this default is that it makes slightly different images every single time you link the same sources. So --no-insert-timestamp can be used to insert a zero value for the timestamp instead, making sure binaries produced from identical sources compare identically. 💅

If --insert-timestamp is active, then the time inserted is either the time that the linking takes place, or — if the "SOURCE_DATE_EPOCH" environment variable is defined — the number of seconds since Unix epoch as specified by that variable.

  • --enable-reloc-section
  • --disable-reloc-section — create the base relocation table, which is necessary if the image gets loaded at a different image base than the one specified in the PE header. Enabled by default.

✨ C6X uClinux / DSBT moment ✨

The C6X uClinux target uses a binary format called DSBT to support shared libraries. Every shared library in the system needs a unique index; all executables use an index of 0.

  • --dsbt-size size — sets the number of entries in the DSBT of the current executable or shared library to size. Default is to create a table with 64 entries.
  • --dsbt-index index — sets the DSBT index of the current executable or shared library to index. Default is 0, which is the right vibe for generating executables. If a shared library is generated with a DSBT index of 0, the "R_C6000_DSBT_INDEX" relocs get copied into the output file. 🦋

The --no-merge-exidx-entries switch disables the merging of adjacent exidx entries in frame unwind info.

  • --branch-stub — enables linker branch relaxation by inserting branch stub sections when needed to extend the range of branches. Usually not required, since C-SKY supports branch and call instructions that can access the full memory range, and branch relaxation is normally handled by the compiler or assembler.
  • --stub-group-size=N — finer control over linker branch stub creation. It sets the maximum size of a group of input sections that one stub section can handle. A negative value of N puts stub sections after their branches, while a positive value lets stub sections appear either before or after the branches. Values of 1 or -1 mean the linker should pick suitable defaults.

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

  • --no-trampoline — disables the generation of trampoline. By default a trampoline is generated for each far function that's called using a "jsr" instruction (this happens when a pointer to a far function is taken).
  • --bank-window name — tells the linker the name of the memory region in the MEMORY specification that describes the memory bank window. That region's definition is then used by the linker to compute paging and addresses within the memory window.

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

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

The following options are supported to control microMIPS instruction generation and branch relocation checks for ISA mode transitions when linking for MIPS targets.

  • --insn32
  • --no-insn32 — these control the choice of microMIPS instructions used in code generated by the linker, like in the PLT or lazy binding stubs, or in relaxation. If --insn32 is used, the linker only uses 32-bit instruction encodings. By default, or if --no-insn32 is used, all instruction encodings are used, including 16-bit ones where possible.
  • --ignore-branch-isa
  • --no-ignore-branch-isa — these control branch relocation checks for invalid ISA mode transitions. If --ignore-branch-isa is used, the linker accepts any branch relocations and any ISA mode transition required is lost in relocation calculation — except for some cases of "BAL" instructions that meet relaxation conditions and get converted to equivalent "JALX" instructions as the associated relocation is calculated. By default, or if --no-ignore-branch-isa is used, a check is made that turns the loss of an ISA mode transition into an error. 😭
  • --compact-branches
  • --no-compact-branches — these control the generation of compact instructions by the linker in the PLT entries for MIPS R6. 💜

okay bestie, one last little corner of linker lore: the pdp11-aout target has THREE whole output-format variants, and you pick them with these options. For the pdp11-aout target, three variants of the output format can be produced as selected by the following options. The default variant for pdp11-aout is the --omagic option, whereas for other targets --nmagic is the default. The --imagic option is defined <em>only</em> for the pdp11-aout target, while the others are described here as they apply to the pdp11-aout target. 🎀

  • -N, --omagic — marks the output as "OMAGIC" (0407) in the a.out header to indicate that the text segment is not to be write-protected and shared. Since the text and data sections are both readable and writable, the data section is allocated immediately contiguous after the text segment. This is the oldest format for PDP11 executable programs and is the default for ld on PDP11 Unix systems from the beginning through 2.11BSD. 🧚
  • -n, --nmagic — marks the output as "NMAGIC" (0410) in the a.out header to indicate that when the output file is executed, the text portion will be read-only and shareable among all processes executing the same file. This involves moving the data areas up to the first possible 8K byte page boundary following the end of the text. This option creates a pure executable format. ✨
  • -z, --imagic — marks the output as "IMAGIC" (0411) in the a.out header to indicate that when the output file is executed, the program text and data areas will be loaded into separate address spaces using the split instruction and data space feature of the memory management unit in larger models of the PDP11. This doubles the address space available to the program. The text segment is again pure, write-protected, and shareable. The only difference in the output format between this option and the others, besides the magic number, is that both the text and data sections start at location 0. The -z option selected this format in 2.11BSD. This option creates a separate executable format. 💅
  • --no-omagic — equivalent to --nmagic for pdp11-aout. 🦋

🌸 ENVIRONMENT 🌸

You can change the behaviour of ld with the environment variables GNUTARGET, LDEMULATION and COLLECT_NO_DEMANGLE. no cap, they really do move the vibe. 💖

GNUTARGET determines the input-file object format if you don't use -b (or its synonym --format). Its value should be one of the BFD names for an input format. If there is no GNUTARGET in the environment, ld uses the natural format of the target. If GNUTARGET is set to default then BFD attempts to discover the input format by examining binary input files; this method often succeeds, but there are potential ambiguities, since there is no method of ensuring that the magic number used to specify object-file formats is unique. However, the configuration procedure for BFD on each system places the conventional format for that system first in the search-list, so ambiguities are resolved in favor of convention. 🔍

LDEMULATION determines the default emulation if you don't use the -m option. The emulation can affect various aspects of linker behaviour, particularly the default linker script. You can list the available emulations with the --verbose or -V options. If the -m option is not used, and the LDEMULATION environment variable is not defined, the default emulation depends upon how the linker was configured. ⚙️

Normally, the linker will default to demangling symbols. However, if COLLECT_NO_DEMANGLE is set in the environment, then it will default to not demangling symbols. This environment variable is used in a similar fashion by the gcc linker wrapper program. The default may be overridden by the --demangle and --no-demangle options. 🫶

If the PE/COFF specific --insert-timestamp is active and the SOURCE_DATE_EPOCH environment variable is defined, then the timestamp value in this variable will be inserted into the COFF header instead of the current time. ⏰

If the LD_STATS environment variable is defined then linker resource use information will be recorded, just as if the --stats option had been used. If the LD_STATS variable has a string value then this will be used as the name of a file into which the information should be stored. Otherwise the information will be sent to the standard output stream. 📊

✨ SEE ALSO ✨

Copyright (c) 1991-2026 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". 📜

That's the whole page, bestie! This manual page is from binutils-2.46.1, dated 2026-09-07, and it's the LD(1) page. Go forth and link slayfully. 💅✨
📦 where this page comes from
  • fedora 44: cross-binutils-common 2.46.1-1.fc44 · GPL-3.0-or-later AND (GPL-3.0-or-later WITH Bison-exception-2.2) AND (LGPL-2.0-or-later WITH GCC-exception-2.0) AND BSD-3-Clause AND GFDL-1.3-or-later AND GPL-2.0-or-later AND LGPL-2.1-or-later AND LGPL-2.0-or-later
  • 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on : a language model's rewrite of the original, under its terms