LD(1)
💖 LD(1) 💖
GNU Development Tools · the GNU linker — bestie edition 🎀
✨ NAME ✨
ld — the GNU linker. that's it, that's the girl 💅
🌸 SYNOPSIS 🌸
ld [options] objfile ...🦋 DESCRIPTION 🦋
okay so picture this: ld takes a whole pile of object files and archive files, relocates their data, and ties up symbol references. that's literally her whole job. and like, usually? the very last step of compiling a program is running ld. the finale. the main character moment. 👑
ld accepts Linker Command Language files written in a superset of AT&T's Link Editor Command Language syntax, which gives you explicit and total control over the linking process. total control. she said what she said.
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 theldentry ininfo. this page is the vibe summary, not the whole saga.
this version of ld uses the general purpose BFD libraries to operate on object files. that's how she can read, combine, and write object files in so 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. she's flexible like that 💅
aside from the flexibility, the GNU linker is more helpful than other linkers when it comes to diagnostic information. so many linkers just abandon execution the second they hit an error 😭 but ld, whenever possible, continues executing, letting you identify other errors — or, in some cases, get an output file in spite of the error. she's not a quitter, periodt.
the GNU linker ld is meant to cover a broad range of situations and to be as compatible as possible with other linkers. as a result, you have many choices to control her behavior. choices are iconic, actually. 🌈
✨ OPTIONS ✨
the linker supports a plethora of command-line options, but ngl, in actual practice 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 such a system, to link a file hello.o:
ld -o <output> /lib/crt0.o hello.o -lcthis tells ld to produce a file called output as the result of linking the file /lib/crt0.o with hello.o and the library libc.a, which will come from the standard search directories. (see the discussion of the -l option below 👇)
some of the command-line options to ld may be specified at any point in the command line. however — options which refer to files, 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. repeating non-file options with a different argument will either have no further effect, or override prior occurrences (those further to the left on the command line) of that option. options which may be meaningfully specified more than once are noted in the descriptions below. iykyk 📝
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. rude of you to try, honestly.
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. she's petty like that 💀
if the linker cannot recognize the format of an object file, it will assume that it is a linker script. a script specified in this way augments the main linker script used for the link (either the default linker script or the one specified by using -T). this feature permits the linker to link against a file which appears to be an object or an archive, but actually merely defines some symbol values, or uses INPUT or GROUP to load other objects. specifying a script in this way merely augments the main linker script, with the extra commands placed after the main script; use the -T option to replace the default linker script entirely, but note the effect of the INSERT command. sneaky but valid ✨
for options whose names are a single letter, option arguments must either follow the option letter without intervening whitespace, or be given as separate arguments immediately following the option that requires them.
for options whose names are multiple letters, either one dash or two can precede the option name; for example, -trace-symbol and --trace-symbol are equivalent. note — there is one exception to this rule. multiple letter options that start with a lower case o can only be preceded by two dashes. this is to reduce confusion with the -o option. so for example -omagic sets the output file name to magic whereas --omagic sets the NMAGIC flag on the output. tricky little gremlin behavior, but ok 🫶
arguments to multiple-letter options must either be separated from the option name by an equals sign, or be given as separate arguments immediately following the option that requires them. for example, --trace-symbol foo and --trace-symbol=foo are equivalent. unique abbreviations of the names of multiple-letter options are accepted.
note — if the linker is being invoked indirectly, via a compiler driver (e.g.gcc) then all the linker command-line options should be prefixed by-Wl,(or whatever is appropriate for the particular compiler driver) like this:
gcc -Wl,--start-group foo.o bar.o -Wl,--end-groupthis is important, because otherwise the compiler driver program may silently drop the linker options, resulting in a bad link. confusion may also arise when passing options that require values through a driver, as the use of a space between option and argument acts as a separator, and causes the driver to pass only the option to the linker and the argument to the compiler. in this case, it is simplest to use the joined forms of both single- and multiple-letter options, such as:
gcc foo.o bar.o -Wl,-eENTRY -Wl,-Map=a.maphere is a table of the generic command-line switches accepted by the GNU linker: 👇
@file— read command-line options from file. the options read are inserted in place of the original@fileoption. 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. it's giving inception 🌀
-akeyword — this option is supported for HP/UX compatibility. the keyword argument must be one of the stringsarchive,shared, ordefault.-aarchiveis functionally equivalent to-Bstatic, and the other two keywords are functionally equivalent to-Bdynamic. this option may be used any number of times.--auditAUDITLIB — adds AUDITLIB to theDT_AUDITentry of the dynamic section. AUDITLIB is not checked for existence, nor will it use theDT_SONAMEspecified in the library. if specified multiple timesDT_AUDITwill 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 correspondingDT_DEPAUDITentry in the output file. this option is only meaningful on ELF platforms supporting the rtld-audit interface.-binput-format--format=input-format
ld may be configured to support more than one kind of object file. if your ld is configured this way, you can use the -b option to specify the binary format for input object files that follow this option on the command line. even when ld is configured to support alternative object formats, you don't usually need to specify this, as ld should be configured to expect as a default input format the most usual format on each machine. input-format is a text string, the name of a particular format supported by the BFD libraries. (you can list the available binary formats with objdump -i.)
you may want to use this option if you are linking files with an unusual binary format. you can also use -b to switch formats explicitly (when linking object files of different formats), by including -b input-format before each group of object files in a particular format.
the default format is taken from the environment variable GNUTARGET.
you can also define the input format from a script, using the command TARGET;
-cMRI-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 commandFORCE_COMMON_ALLOCATIONhas the same effect. three names, one girl 💅--depauditAUDITLIB-PAUDITLIB
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 theLINKER_VERSIONlinker 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 theLINKER_VERSIONlinker script directive, so that it does not insert a version string. this is the default.--enable-non-contiguous-regions— okay so bestie, this one is giving chill linker energy. Normally if an input section doesn't fit its matching output section,ldis like "absolutely not" and throws an error. With this flag? It just goes "bet" and tries to shove that input section into the next matching output section, and only actually errors out if no output section is big enough. Iconic for when you've got several non-contiguous memory regions lying around and your input section isn't picky about which one it lands in. ✨
The order in which input sections are evaluated does not change — like, at all. For instance:
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 4results in .data.1 affected to mem1, and .data.2 and .data.3 affected to mem2, even though .data.3 would fit in mem3. 💀 Yeah. It said what it said.
Heads up bestie: 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-regionsallows possibly unexpected matches in sections mapping. And like, why do we care? Because those sneaky matches can potentially lead to silently discarding a section instead of failing because it doesn't fit any output region. 🙈 Warning = self care.-eentry /--entry=entry — use entry as the explicit symbol for beginning execution of your program, instead of the default entry point. Main character selection, basically. 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; you may use a leading0xfor base 16, or a leading0for base 8). For i386 PE, entry can also be the original function name (without the leading underscore and/or the trailing stdcall@numberwhen applicable).--exclude-libslib,lib,... — specifies a list of archive libraries from which symbols should not be automatically exported. The library names may be delimited by commas or colons. Saying--exclude-libs ALLexcludes symbols in all archive libraries from automatic export. 🚫✨
This option is available only for ELF and PE targeted ports of the linker.
For PE targets, symbols explicitly listed in a .def file are still exported, regardless of this option. For ELF targeted ports, symbols affected by this option will be treated as hidden.
--exclude-modules-for-implibmodule,module,... — specifies a list of object files or archive members from which symbols should not be automatically exported, but which should be copied wholesale into the import library being generated during the link. The module names may be delimited by commas or colons, and must match exactly the filenames used byldto open the files — for archive members, this is simply the member name, but for object files the name listed must include and match precisely any path used to specify the input file on the linker's command-line. Symbols explicitly listed in a.deffile are still exported, regardless of this option. 🫶
[This option is specific to PE targeted ports of the linker]
-E/--export-dynamic/--no-export-dynamic— when you're creating a dynamically linked executable, using-Eor--export-dynamiccauses the linker to add all symbols to the dynamic symbol table. The dynamic symbol table is the set of symbols which are visible from dynamic objects at run time. It's giving "everyone's invited to the party." 🎉
If you don't use either of these options (or if you use --no-export-dynamic to restore the default behavior), the dynamic symbol table will normally contain only those symbols which are referenced by some dynamic object mentioned in the link.
If you use dlopen to load a dynamic object which needs to refer back to the symbols defined by the program — rather than some other dynamic object — then you will probably need to use this option when linking the program itself. iykyk.
You can also use the dynamic list to control what symbols should be added to the dynamic symbol table if the output format supports it. See the description of --dynamic-list. 📋
Note that this option is specific to ELF targeted ports. PE targets support a similar function to export all symbols from a DLL or EXE; see the description of --export-all-symbols below.
--export-dynamic-symbol=glob — when creating a dynamically linked executable, symbols matching glob will be 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-Bsymbolicor--dynamic-listare not specified. This option is only meaningful on ELF platforms which support shared libraries. 💅--export-dynamic-symbol-list=file — specify a--export-dynamic-symbolfor each pattern in the file. The format of the file is the same as the version node without scope and node name. SeeVERSIONfor more information.-EB— link big-endian objects. This affects the default output format. 🐘 (big endian, big energy, no I will not elaborate)-EL— link little-endian objects. This affects the default output format. 🐭-fname /--auxiliary=name — when creating an ELF shared object, set the internalDT_AUXILIARYfield to the specified name. This tells the dynamic linker that the symbol table of the shared object should be used as an auxiliary filter on the symbol table of the shared object name. ✨
If you later link a program against this filter object, then when you run the program, the dynamic linker will see the DT_AUXILIARY field. If the dynamic linker resolves any symbols from the filter object, it will first check whether there is a definition in the shared object name. If there is one, it will be used instead of the definition in the filter object. The shared object name need not exist. So basically name may be used to provide an alternative implementation of certain functions — perhaps for debugging, or for machine-specific performance. Slay.
This option may be specified more than once. The DT_AUXILIARY entries will be created in the order in which they appear on the command line. 🔥
-Fname /--filter=name — when creating an ELF shared object, set the internalDT_FILTERfield to the specified name. This tells the dynamic linker that the symbol table of the shared object which is being created should be used as a filter on the symbol table of the shared object name.
If you later link a program against this filter object, then when you run the program, the dynamic linker will see the DT_FILTER field. The dynamic linker will resolve symbols according to the symbol table of the filter object as usual, but it will actually link to the definitions found in the shared object name. So the filter object can be used to select a subset of the symbols provided by the object name. It's giving curated playlist. 🎀
Some older linkers used the-Foption throughout a compilation toolchain for specifying object-file format for both input and output object files. The GNU linker uses other mechanisms for this purpose: the-b,--format,--oformatoptions, theTARGETcommand in linker scripts, and theGNUTARGETenvironment variable. The GNU linker will ignore the-Foption when not creating an ELF shared object. 💀
-fini=name — when creating an ELF executable or shared object, callNAMEwhen the executable or shared object is unloaded, by settingDT_FINIto the address of the function. By default, the linker uses_finias the function to call. 🫡-g— Ignored. Provided for compatibility with other tools. She's just standing there. 🧍♀️-Gvalue /--gpsize=value — set the maximum size of objects to be optimized using the GP register to value. This is only meaningful for object file formats such as MIPS ELF that support putting large and small objects into different sections. This is ignored for other object file formats. 🧚-hname /-soname=name — when creating an ELF shared object, set the internalDT_SONAMEfield to the specified name. When an executable is linked with a shared object which has aDT_SONAMEfield, then when the executable is run the dynamic linker will attempt to load the shared object specified by theDT_SONAMEfield rather than using the file name given to the linker. 👑-i— perform an incremental link (same as option-r). Same thing, different letter. 💫-init=name — when creating an ELF executable or shared object, callNAMEwhen the executable or shared object is loaded, by settingDT_INITto the address of the function. By default, the linker uses_initas the function to call. 🌅 (yes it's the twin of-fini, and yes they're both iconic)-lnamespec /--library=namespec — add the archive or object file specified by namespec to the list of files to link. This option may be used any number of times — go off. If namespec is of the form:filename,ldwill search the library path for a file calledfilename, otherwise it will search the library path for a file calledlibnamespec.a. 🍓
On systems which support shared libraries, ld may also search for files other than libnamespec.a. Specifically, on ELF and SunOS systems, ld will search a directory for a library called libnamespec.so before searching for one called libnamespec.a. (By convention, a .so extension indicates a shared library.) Note that this behavior does not apply to :filename, which always specifies a file called filename.
The linker will search an archive only once, at the location where it is specified on the command line. If the archive defines a symbol which was undefined in some object which appeared before the archive on the command line, the linker will include the appropriate file(s) from the archive. However, an undefined symbol in an object appearing later on the command line will not cause the linker to search the archive again. ⚠️ Order matters, bestie. It always does.
See the -( option for a way to force the linker to search archives multiple times. 🔁
You may list the same archive multiple times on the command line. No judgement. 💖
This type of archive searching is standard for Unix linkers. But bestie, heads up — if you're using ld on AIX, it is different from the behaviour of the AIX linker. iykyk. 🫶
-L searchdir,--library-path=searchdir— add pathsearchdirto the list of paths thatldwill search for archive libraries andldcontrol scripts. You can use this option any number of times 💅 — the directories get searched in the order you specified them on the command line. Directories you name on the command line get searched before the default directories. And the way that all-Loptions apply to all-loptions, regardless of the order they appear? iconic. One thing though:-Loptions do not affect howldsearches for a linker script unless the-Toption is specified. ✨
If searchdir begins with "=" or $SYSROOT, then that prefix gets replaced by the sysroot prefix — controlled by the --sysroot option, or specified when the linker was configured.
The default set of paths searched (when you didn't specify them with -L) depends on which emulation mode ld is using, and in some cases also on how it was configured.
You can also specify the paths in a link script with the "SEARCH_DIR" command. Directories specified that way get searched at the point in which the linker script appears in the command line. 🎀
-m emulation— emulate the emulation linker. You can list all the available emulations with the--verboseor-Voptions. 👑
If the -m option is not used, the emulation is taken from the "LDEMULATION" environment variable, if that is defined.
Otherwise, the default emulation depends upon how the linker was configured.
--remap-inputs=pattern=filename,--remap-inputs-file=file— these options let the names of input files be changed before the linker even attempts to open them. The option--remap-inputs=foo.o=bar.owill cause any attempt to load a file calledfoo.oto instead try to load a file calledbar.o. Wildcard patterns are permitted in the first filename, so--remap-inputs=foo*.o=bar.owill rename any input file that matchesfoo*.otobar.o. 🌈
There's an alternative form of the option, --remap-inputs-file=filename, which lets the remappings be read from a file. Each line in the file can contain a single remapping. Blank lines are ignored. Anything from a hash character (#) to the end of a line is considered to be a comment and is also ignored. The mapping pattern can be separated from the filename by whitespace or an equals (=) character. ✨
These options can be specified multiple times, and their contents accumulate. The remappings get processed in the order in which they occur on the command line, and if they come from a file, in the order in which they occur in the file. If a match is made, no further checking for that filename will be performed.
If the replacement filename is /dev/null or just NUL then the remapping will actually cause the input file to be ignored. This can be a convenient way to experiment with removing input files from a complicated build environment. 🙈
Note that this option is position dependent and only affects filenames that come after it on the command line. Thus:
ld foo.o --remap-inputs=foo.o=bar.oWill have no effect, whereas:
ld --remap-inputs=foo.o=bar.o foo.oWill rename the input file foo.o to bar.o. 💅
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.
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 remaped filenames appear. (yes, "remaped", that's the original spelling bestie, we don't edit facts 🫶)
If the -Map or --print-map options are enabled then the remapping list will be included in the map output.
-M,--print-map— print a link map to the standard output. A link map provides information about the link, including the following:- Where object files are mapped into memory. 🗺️
- How common symbols are allocated.
- All archive members included in the link, with a mention of the symbol which caused the archive member to be brought in.
- The values assigned to symbols.
Note — symbols whose values are computed by an expression which involves a reference to a previous value of the same symbol may not have correct result displayed in the link map. This is because the linker discards intermediate results and only retains the final value of an expression. Under such circumstances the linker will display the final value enclosed by square brackets. Thus for example a linker script containing:
foo = 1
foo = foo * 4
foo = foo + 8will 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. slay. 💖
- On some ELF targets, a list of fixups inserted by
--relax:
foo.o: Adjusting branch at 0x00000008 towards "far" in section .textThis 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 do not print) the list of discarded and garbage collected sections in the link map. Enabled by default.--print-map-locals,--no-print-map-locals— print (or do not 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. 😭
--no-omagic— this option negates most of the effects of the-Noption. It sets the text section to be read-only, and forces the data segment to be page-aligned.
Note — this option does not enable linking against shared libraries. Use -Bdynamic for this. 🌸
-o output,--output=output— useoutputas the name for the program produced byld; if this option is not specified, the namea.outis used by default. The script command"OUTPUT"can also specify the output file name.
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. 💀
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. bestie please put -o last, I am begging 🙏
--dependency-file=depfile— write a dependency file todepfile. 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-fileis always specific to the exact state of the installation where it was produced, and should not be copied into distributed makefiles without careful editing. 📝-O level— if level is a numeric values greater than zeroldoptimizes 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. ⭐
If level is zero or the string fast, then ld lowkey just skips operations that are optional — which gives you a faster link but the binaries come out slower and chunkier. rn the only operation being skipped is the combining of mergeable sections, but bestie, this may change in the future. 👀
If level is the string default or literally just the - character, then you get the linker's default behaviour of neither optimizing nor skipping anything. Chill. 🧘
-pluginname — get a plugin involved in the linking process, fr. The name parameter is the absolute filename of the plugin. Usually this parameter is automatically added by the compiler when you're doing link time optimization, but bestie you can also add your own plugins if you so wish. 💅
Heads up: the location of the compiler-originated plugins is different from the place where thear,nmandranlibprograms search for their plugins. For those commands to make use of a compiler based plugin it must first be copied into the${libdir}/bfd-pluginsdirectory. All gcc based linker plugins are backward compatible, so it is sufficient to just copy in the newest one. 🫶
--push-state— this one lets you preserve the current state of the flags that govern input file handling, so they can all be restored later with one corresponding--pop-stateoption. Iconic. ✨
The options which are covered are: -Bdynamic, -Bstatic, -dn, -dy, -call_shared, -non_shared, -static, -N, -n, --whole-archive, --no-whole-archive, --link-mapless, --no-link-mapless, -r, -Ur, --copy-dt-needed-entries, --no-copy-dt-needed-entries, --as-needed, --no-as-needed, and -a.
One target for this option is specifications for pkg-config. When used with the --libs option, all possibly needed libraries are listed and then possibly linked with all the time. It's way better to return something like this:
-Wl,--push-state,--as-needed -libone -libtwo -Wl,--pop-state--pop-state— undoes the effect of--push-state, and restores the previous values of the flags governing input file handling. the way that these two are a matched set… 😌
-q,--emit-relocs— leave relocation sections and contents in fully linked executables. Post link analysis and optimization tools may need this info to perform correct modifications of executables. Downside bestie: this results in larger executables. 🫠
This option is currently only supported on ELF platforms.
--force-dynamic— force the output file to have dynamic sections. This option is specific to VxWorks targets.-r,--relocatable— generate relocatable output, i.e. generate an output file that can in turn serve as input told. This is often called partial linking. As a side effect, in environments that support standard Unix magic numbers, this option also sets the output file's magic number to"OMAGIC". If this option is not specified, an absolute file is produced. When linking C++ programs, this option will not resolve references to constructors — to do that, use-Ur. 💅
When an input file does not have the same format as the output file, partial linking is only supported if that input file does not contain any relocations. Different output formats can have further restrictions; for example some "a.out"-based formats do not support partial linking with input files in other formats at all. 😭
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. 🧚
Ngl, 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.
This option does the same thing as -i.
-Rfilename,--just-symbols=filename — read symbol names and their addresses from filename, but do 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 the -R option is followed by a directory name rather than a file name, it is treated as the -rpath option.
--rosegment,--no-rosegment— attempt to ensure that only a single read-only, non-code segment is created. Only useful when used in conjunction with the-z separate-codeoption. The resulting binaries should be smaller than if-z separate-codeis used on its own. Without this option, or if--no-rosegmentis specified, the-z separate-codeoption will create two read-only segments — one before the code segment and one after it.
The names of the options are misleading, but they have been chosen in order for the linker to be compatible with the LLD and GOLD linkers. iykyk.
These options are only supported by ELF targets.
-s,--strip-all— omit all symbol information from the output file. bye symbols 👋-S,--strip-debug— omit debugger symbol information (but not all symbols) from the output file.--strip-discarded,--no-strip-discarded— omit (or do not omit) global symbols defined in discarded sections. Enabled by default.-plugin-save-temps— store the plugin "temporary" intermediate files permanently. no take-backs ✨-t,--trace— print the names of the input files asldprocesses them. If-tis given twice, then members within archives are also printed.-toutput is useful to generate a list of all the object files and scripts involved in linking, for example when packaging files for a linker bug report. 🐛-Tscriptfile,--script=scriptfile — use scriptfile as the linker script. This script replacesld's default linker script (rather than adding to it), unless the script contains"INSERT", so commandfile must specify everything necessary to describe the output file. 👑
If scriptfile does not exist in the current directory, ld looks for it in the directories specified by any preceding -L options.
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
-dTscriptfile,--default-script=scriptfile — use scriptfile as the default linker script.
This option is similar to the --script option except that processing of the script is delayed until after the rest of the command line has been processed. This allows options placed after the --default-script option on the command line to affect the behaviour of the linker script, which can be important when the linker command line cannot be directly controlled by the user (e.g. because the command line is being constructed by another tool, such as gcc). 🛠️
-usymbol,--undefined=symbol — force symbol to be entered in the output file as an undefined symbol. Doing this may, for example, trigger linking of additional modules from standard libraries.-umay be repeated with different option arguments to enter additional undefined symbols. This option is equivalent to the"EXTERN"linker script command.
If this option is being used to force additional modules to be pulled into the link, and if it is an error for the symbol to remain undefined, then the option --require-defined should be used instead.
--require-defined=symbol — require that symbol is defined in the output file. This option is the same as option--undefinedexcept that if symbol is not defined in the output file then 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 do not 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 in turn serve as input told. For other binaries however the-Uroption is similar to-rbut 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. Use -Ur only for the last partial link, and -r for the others. periodt.
--orphan-handling=MODE — control 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--uniquealso 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— display the version number forld. The-Voption also lists the supported emulations. See also the description of the--enable-linker-versionin Options,,Command-line Options which can be used to insert the linker version string into a binary. ⭐-x,--discard-all— delete all local symbols. 🗑️-X,--discard-locals— bye-bye to all the temp local symbols ✨ (these are the ones that start with system-specific local label prefixes — usually.Lon ELF systems, orLon traditional a.out systems, iykyk).-ysymbol,--trace-symbol=symbol — prints the name of every linked file where symbol shows up 👀. You can hand this flag as many times as you want, no cap. On lots of systems you gotta prepend an underscore, so like_symbol, periodt.
Lowkey this one is a lifesaver when you've got an undefined symbol in your link and you're sitting there like "who is she and where is she coming from??" 😭 This is the answer.
-Ypath — adds path to the default library search path. It only exists for Solaris compatibility, bestie, that's the whole vibe. 🫶-zkeyword — okay so this is the icon, the main character, the whole buffet 🍓. The recognized keywords are:call-nop=prefix-addrcall-nop=suffix-nopcall-nop=prefix-bytecall-nop=suffix-byte— these four tell the linker which 1-byte"NOP"padding to slap in when it's transforming an indirect call to a locally defined function,foo, through its GOT slot.call-nop=prefix-addrgives you"0x67 call foo".call-nop=suffix-nopgives you"call foo 0x90".call-nop=prefix-bytegives you"byte call foo".call-nop=suffix-bytegives you"call foo byte".
Supported for i386 and x86_64. 💅
cet-report=nonecet-report=warningcet-report=error— this one decides how to report the missingGNU_PROPERTY_X86_FEATURE_1_IBTandGNU_PROPERTY_X86_FEATURE_1_SHSTKproperties in the input.note.gnu.propertysection.cet-report=none— and this one is the default, bestie — makes the linker just not report missing properties in input files.cet-report=warningmakes the linker issue a warning for missing properties in input files.cet-report=errormakes the linker issue an error 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. 🐧
combrelocnocombreloc— combines multiple dynamic relocation sections and sorts them so dynamic symbol lookup caching gets a glow-up ✨. Do not do this ifnocombreloc.commonnocommon— generates common symbols withSTT_COMMONtype during a relocatable link. UseSTT_OBJECTtype ifnocommon.common-page-size=value — sets the page size most commonly used to value. Memory image layout gets optimized to minimize memory pages if the system is using pages of this size.defs— reports unresolved symbol references from regular object files 📢. This happens even if the linker is creating a non-symbolic shared library. This option is the inverse of-z undefs.dynamic-undefined-weaknodynamic-undefined-weak— makes undefined weak symbols dynamic when building a dynamic object, if they're referenced from a regular object file and not forced local by symbol visibility or versioning. Do not make them dynamic ifnodynamic-undefined-weak. If neither option is given, a target may default to either option being in force, or make some other selection of undefined weak symbols dynamic. Not all targets support these options, so don't @ us. 🙈execstack— marks the object as requiring executable stack.global— this one is only meaningful when building a shared object. It makes the symbols defined by this shared object available for symbol resolution of subsequently loaded libraries.globalaudit— only meaningful when building a dynamic executable. This option 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--depauditor-Pcommand-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— generatesGNU_PROPERTY_X86_FEATURE_1_IBTin the.note.gnu.propertysection to indicate compatibility with IBT. This also impliesibtplt. Supported for Linux/i386 and Linux/x86_64. 🧚indirect-extern-accessnoindirect-extern-access— generatesGNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESSin the.note.gnu.propertysection to indicate that the object file requires canonical function pointers and cannot be used with copy relocation. This option also impliesnoextern-protected-dataandnocopyreloc. Supported for i386 and x86-64.
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 will occur before the runtime initialization of any other objects brought into the process at the same time 👑. Similarly the runtime finalization of the object will occur after the runtime finalization of any other objects.interpose— 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.uniquenounique— 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 function correctly unless they are the sole instances of themselves. This behaviour can be overridden by the"dlmopen"caller and does not apply to certain loading mechanisms (such as audit libraries).lam-u48— generatesGNU_PROPERTY_X86_FEATURE_1_LAM_U48in the.note.gnu.propertysection to indicate compatibility with Intel LAM_U48. Supported for Linux/x86_64.lam-u57— generatesGNU_PROPERTY_X86_FEATURE_1_LAM_U57in the.note.gnu.propertysection to indicate compatibility with Intel LAM_U57. Supported for Linux/x86_64.lam-u48-report=nonelam-u48-report=warninglam-u48-report=error— decides how to report the missingGNU_PROPERTY_X86_FEATURE_1_LAM_U48property in the input.note.gnu.propertysection.lam-u48-report=none— the default, bestie — makes the linker not report missing properties in input files.lam-u48-report=warningmakes the linker issue a warning for missing properties in input files.lam-u48-report=errormakes the linker issue an error for missing properties in input files.
Supported for Linux/x86_64.
lam-u57-report=nonelam-u57-report=warninglam-u57-report=error— decides how to report the missingGNU_PROPERTY_X86_FEATURE_1_LAM_U57property in the input.note.gnu.propertysection.lam-u57-report=none— the default — makes the linker not report missing properties in input files.lam-u57-report=warningmakes the linker issue a warning for missing properties in input files.lam-u57-report=errormakes the linker issue an error for missing properties in input files.
Supported for Linux/x86_64.
lam-report=nonelam-report=warninglam-report=error— decides how to report the missingGNU_PROPERTY_X86_FEATURE_1_LAM_U48andGNU_PROPERTY_X86_FEATURE_1_LAM_U57properties in the input.note.gnu.propertysection.lam-report=none— the default — makes the linker not report missing properties in input files.lam-report=warningmakes the linker issue a warning for missing properties in input files.lam-report=errormakes the linker issue 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 to the point when the function is called (lazy binding), rather than at load time. Lazy binding is the default, so it's giving "I already do this" energy. 😌loadfltr— says that the object's filters be processed immediately at runtime.max-page-size=value — sets the maximum memory page size supported to value.mark-pltnomark-plt— marks PLT entries with dynamic tags,DT_X86_64_PLT,DT_X86_64_PLTSZandDT_X86_64_PLTENT. Because this option stores a non-zero value in ther_addendfield ofR_X86_64_JUMP_SLOTrelocations, the resulting executables and shared libraries are incompatible with dynamic linkers, such as those in older versions of glibc without the change to ignorer_addendinR_X86_64_GLOB_DATandR_X86_64_JUMP_SLOTrelocations, which don't ignore ther_addendfield ofR_X86_64_JUMP_SLOTrelocations. 💀 Supported for x86_64.
bestie this one is a whole warning label, not a cute accessory. read it twice.
muldefs— allows multiple definitions. Go off, do your thing.nocopyreloc— disables linker generated.dynbssvariables used in place of variables defined in shared libraries. May result in dynamic text relocations.nodefaultlib— says that the dynamic loader search for dependencies of this object should ignore any default library search paths.nodelete— says that the object shouldn't be unloaded at runtime. She stays. 💅nodlopen— says that the object is not available to"dlopen".nodump— says that the object can not be dumped by"dldump".noexecstack— marks the object as not requiring 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 compiler. Updates on protected data symbols by another module aren't visible to the resulting shared library. Supported for i386 and x86-64.
-z noreloc-overflow— turns OFF the relocation overflow check 💅 only do this if you know there's not gonna be any dynamic relocation overflow at run-time, bestie. Supported for x86_64.-z memory-seal,-z nomemory-seal— tells the executable or shared library that all thePT_LOADsegments should be sealed so nobody can mess with them anymore (no changing the protection flags, no resizing the segment, no straight-up removing the mapping 🙈). It's a security hardening that requires system support, so it's giving "only works if your system is in on the plan". This generatesGNU_PROPERTY_MEMORY_SEALin the.note.gnu.propertysection. ✨-z now— when you're generating an executable or shared library, this marks it so the dynamic linker resolves all the symbols right when the program starts, or right when the shared library gets loaded bydlopen, instead of deferring function call resolution until the function is literally first called. eager girl behavior, no procrastination 🫶-z origin— specifies that the object requires$ORIGINhandling in paths. 🦋-z pack-relative-relocs,-z nopack-relative-relocs— generate compact relative relocation in position-independent executable and shared library 🎀 it addsDT_RELR,DT_RELRSZandDT_RELRENTentries to the dynamic section. It is ignored when building position-dependent executable and relocatable output.nopack-relative-relocsis the default, which disables compact relative relocation. When linked against the GNU C Library, aGLIBC_ABI_DT_RELRsymbol version dependency on the shared C Library is added to the output. Supported for i386 and x86-64. ✨-z relro,-z norelro— creates an ELFPT_GNU_RELROsegment header in the object 🔥 this specifies a memory segment that should be made read-only after relocation, if supported. Heads up though: specifyingcommon-page-sizesmaller than the system page size will render this protection ineffective 😭 Don't create an ELFPT_GNU_RELROsegment ifnorelro.-z report-relative-reloc— report dynamic relative relocations generated by the linker 👀 Supported for Linux/i386 and Linux/x86_64.-z sectionheader,-z nosectionheader— generate section header. Don't generate section header ifnosectionheaderis used.sectionheaderis the default. 💖-z separate-code,-z noseparate-code— creates a separate codePT_LOADsegment header in the object 🧚 this specifies a memory segment that should contain only instructions and must be in wholly disjoint pages from any other data. Don't create separate codePT_LOADsegment ifnoseparate-codeis used.-z shstk— generateGNU_PROPERTY_X86_FEATURE_1_SHSTKin the.note.gnu.propertysection to indicate compatibility with Intel Shadow Stack 🌈 Supported for Linux/i386 and Linux/x86_64.- *
-z stack-size=value* — specify a stack size for an ELFPT_GNU_STACKsegment. Specifying zero will override any default non-zero sizedPT_GNU_STACKsegment creation. 💅 -z start-stop-gc,-z nostart-stop-gc— okay so when--gc-sectionsis in effect, a reference from a retained section to__start_SECNAMEor__stop_SECNAMEcauses all input sections namedSECNAMEto also be retained, ifSECNAMEis representable as a C identifier and either__start_SECNAMEor__stop_SECNAMEis synthesized by the linker.-z start-stop-gcdisables this effect, allowing sections to be garbage collected as if the special synthesized symbols were not defined 🗑️-z start-stop-gchas no effect on a definition of__start_SECNAMEor__stop_SECNAMEin an object file or linker script. Such a definition will prevent the linker providing a synthesized__start_SECNAMEor__stop_SECNAMErespectively, and therefore the special treatment by garbage collection for those references.- *
-z start-stop-visibility=value* — specify the ELF symbol visibility for synthesized__start_SECNAMEand__stop_SECNAMEsymbols. value must be exactlydefault,internal,hidden, orprotected. If no-z start-stop-visibilityoption is given,protectedis used for compatibility with historical practice 🕰️ However, it's highly recommended to use-z start-stop-visibility=hiddenin new programs and shared libraries so that these symbols are not exported between shared objects, which is not usually what's intended. no cap 🙏 -z text,-z notext,-z textoff— report an error ifDT_TEXTRELis set, i.e., if the position-independent or shared object has dynamic relocations in read-only sections. Don't report an error ifnotextortextoff. 💀-z undefs— do not report unresolved symbol references from regular object files, either when creating an executable, or when creating a shared library. This option is the inverse of-z defs. 🫣-z unique-symbol,-z nounique-symbol— avoid duplicated local symbol names in the symbol string table. Append.number to duplicated local symbol names ifunique-symbolis used.nounique-symbolis the default. ✨-z x86-64-baseline,-z x86-64-v2,-z x86-64-v3,-z x86-64-v4— specify the x86-64 ISA level needed in the.note.gnu.propertysection.x86-64-baselinegeneratesGNU_PROPERTY_X86_ISA_1_BASELINE.x86-64-v2generatesGNU_PROPERTY_X86_ISA_1_V2.x86-64-v3generatesGNU_PROPERTY_X86_ISA_1_V3.x86-64-v4generatesGNU_PROPERTY_X86_ISA_1_V4. Supported for Linux/i386 and Linux/x86_64. it's giving leveled up 👑-z isa-level-report=none,-z isa-level-report=all,-z isa-level-report=needed,-z isa-level-report=used— specify how to report x86-64 ISA levels in input relocatable files 👀isa-level-report=none, which is the default, will make the linker not report x86-64 ISA levels in input files.isa-level-report=allwill make the linker report needed and used x86-64 ISA levels in input files.isa-level-report=neededwill make the linker report needed x86-64 ISA levels in input files.isa-level-report=usedwill make the linker 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 us ignoring them, the linker is, for the record)
--gnu-tls-tag,--no-gnu-tls-tag— add aGLIBC_ABI_GNU_TLSversion 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 which doesn't define theGLIBC_ABI_GNU_TLSversion tag 😭 Unless disabled by the--disable-gnu-tls-tagconfigure option at the linker build time, when no options are specified, the linker will add theGLIBC_ABI_GNU_TLSversion tag dependency if inputs have a___tls_get_addrcall andlibc.sodefines theGLIBC_ABI_GNU_TLSversion tag. Supported for Linux/i386.--gnu2-tls-tag,--no-gnu2-tls-tag— add aGLIBC_ABI_GNU2_TLSversion tag dependency in output programs and shared libraries when linking against glibc, if input relocatable object files have anR_386_TLS_DESC_CALLorR_X86_64_TLSDESC_CALLrelocation. The output will fail to load and run at run-time against glibc which doesn't define theGLIBC_ABI_GNU2_TLSversion tag 💀 Unless disabled by the--disable-gnu2-tls-tagconfigure option at the linker build time, when no options are specified, the linker will add theGLIBC_ABI_GNU2_TLSversion tag dependency if inputs have anR_386_TLS_DESC_CALLorR_X86_64_TLSDESC_CALLrelocation andlibc.sodefines theGLIBC_ABI_GNU2_TLSversion 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 may be either explicit file names, or-loptions.
The specified archives are searched repeatedly until no new undefined references are created. Normally, an archive is searched only once, in the order that it is specified on the command line. If a symbol in that archive is needed to resolve an undefined symbol referred to by an object in an archive that appears later on the command line, the linker would not be able to resolve that reference 😭 By grouping the archives, they will all be searched repeatedly until all possible references are resolved. it's giving "we go again until it's done" ✨
This option is not allowed within a--start-lib/--end-liboption pair. 🚫
Using this option has a significant performance cost 😮💨 It is best to use it only when there are unavoidable circular references between two or more archives.
--start-lib objects --end-lib— the objects should be a list of object files.
The specified objects are treated as if they were members of an archive, the name of which has been placed at the location of --start-lib on the command line 🧚 All the usual linker archive handling properties and command line options apply to such an artificial archive. iconic fake-it-till-you-make-it energy 💅
This option may be used multiple times, in which case each set of the objects specified will be treated as an individual archive. Nesting this option is not allowed though. 🙅
Options that affect archive processing are not allowed between --start-lib and --end-lib, as it would make no sense to apply them midway through handling an archive. These options include: -(/--start-group, -)/--end-group, --whole-archive, and --no-whole-archive, as well as --pop-state where it would change the state of the --whole-archive setting. periodt. 📋
--accept-unknown-input-arch,--no-accept-unknown-input-arch— tells the linker to accept input files whose architecture cannot be recognised 🫶 the assumption is that the user knows what they are doing and deliberately wants to link in these unknown input files. This was the default behaviour of the linker before release 2.14. The default behaviour from release 2.14 onwards is to reject such input files, and so the--accept-unknown-input-archoption has been added to restore the old behaviour. throwback era 🕰️✨--as-needed,--no-as-needed— bestie this one is about ELFDT_NEEDEDtags for dynamic libraries named on the command line after--as-neededshows up. Normally the linker is out here adding aDT_NEEDEDtag for every single dynamic library on the command line, whether or not it's actually needed — like, no vibe check at all.--as-neededsays: only emit aDT_NEEDEDtag for a library that, at that point in the link, satisfies a non-weak undefined symbol reference from a regular object file, or — if that library isn't found in theDT_NEEDEDlists of other needed libraries — a non-weak undefined symbol reference from another needed dynamic library. Object files or libraries that show up on the command line after the library in question don't affect whether it's seen as needed. It's giving the same rules as extracting object files from archives, fr fr.--no-as-neededputs the default behaviour back. 💅
Note: on Linux based systems the--as-neededoption also has an affect on the behaviour of the--rpathand--rpath-linkoptions. See the description of--rpath-linkfor more details.
--add-needed,--no-add-needed— these two are deprecated because their names were lowkey too similar to--as-neededand--no-as-neededand everyone kept getting them confused. They've been replaced by--copy-dt-needed-entriesand--no-copy-dt-needed-entries. periodt.-assertkeyword — this option is ignored for SunOS compatibility. that's it, that's the whole thing. 🫶-Bdynamic,-dy,-call_shared— link against dynamic libraries. This is only meaningful on platforms where shared libraries are supported (so, not everywhere, iykyk). On those platforms this option is normally the default. The different variants exist for compatibility with various systems. You can use this option multiple times on the command line: it affects library searching for-loptions which follow it. ✨-Bgroup— sets the"DF_1_GROUP"flag in the"DT_FLAGS_1"entry in the dynamic section. This makes the runtime linker handle lookups in this object and its dependencies only inside the group.--unresolved-symbols=report-allis implied. Only meaningful on ELF platforms which support shared libraries. 👑-Bstatic,-dn,-non_shared,-static— do not link against shared libraries. Only meaningful on platforms where shared libraries are supported. The different variants are for compatibility with various systems. You may use this option multiple times on the command line: it affects library searching for-loptions which follow it. This option also implies--unresolved-symbols=report-all. It can be used with-shared— doing so means a shared library is being created, but that all of the library's external references must be resolved by pulling in entries from static libraries. 💀-Bsymbolic— when creating a shared library, bind references to global symbols to the definition within the shared library, if any. Normally it's possible for a program linked against a shared library to override the definition within the shared library — so this shuts that down. Only meaningful on ELF platforms which support shared libraries. 🌸-Bsymbolic-functions— same energy as-Bsymbolic, but only for global function symbols: when creating a shared library, bind references to global function symbols to the definition within the shared library, if any. Only meaningful on ELF platforms which support shared libraries.-Bno-symbolic— this option can cancel previously specified-Bsymbolicand-Bsymbolic-functions. the undoing, the reversal, the take-backs. 🙈--dynamic-list=dynamic-list-file — hand the linker the name of a dynamic list file. 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 when creating dynamically linked executables, to specify a list of symbols which should be added to the symbol table in the executable. 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 in the dynamic list.--dynamic-list-cpp-new— provide the builtin dynamic list for C++operator newanddelete. Mainly useful for building sharedlibstdc++.--dynamic-list-cpp-typeinfo— provide the builtin dynamic list for C++ runtime type identification.--check-sections,--no-check-sections— asks the linker not to check section addresses after they've been assigned, to see if there are any overlaps. Normally the linker does perform this check, and if it finds overlaps it produces 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 isn't usually checked for relocatable links — you can force checking in that case by using the--check-sectionsoption. 🔥--copy-dt-needed-entries,--no-copy-dt-needed-entries— this one affects how dynamic libraries referred to byDT_NEEDEDtags inside ELF dynamic libraries on the command line get treated. Normally the linker won't add aDT_NEEDEDtag to the output binary for each library mentioned in aDT_NEEDEDtag in an input dynamic library. But with--copy-dt-needed-entrieson the command line, any dynamic libraries that follow it will have theirDT_NEEDEDentries 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 get recursively searched, following theirDT_NEEDEDtags to other libraries, in order to resolve symbols required by the output binary. With the default setting, though, the searching of dynamic libraries that follow it stops with the dynamic library itself — noDT_NEEDEDlinks get 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's printed on the standard output. The format of the table is intentionally simple, so it can 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. ⭐--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 don't 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-variablescauses the generation of such a section. The default behaviour can be restored with--no-ctf-variables.- *
--ctf-share-types=method* — adjusts 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.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. 🧚
--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-commonoption 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-commonallows 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. 💜--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.- *
--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 on 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. not even one little space. the linker will simply not know what you mean. 😭
okay so real talk bestie — the linker goes through --defsym args and -T args in order. So if you drop --defsym before -T, the symbol gets defined before the linker script from -T is even processed. Put --defsym after -T and the symbol gets defined once the linker script is already done. And yeah, that ordering actually matters for any expressions inside the linker script that reference your --defsym symbols. Which order is "correct"? Literally depends on what you're trying to do, no cap. 🦋
--demangle[=style]— turns on demangling of symbol names in error messages and other output. ✨--no-demangle— turns it off. 💅
So what's the demangle tea? When the linker is told to demangle, it tries to show symbol names in a readable way: it strips leading underscores if the object file format uses them, and it converts C++ mangled symbol names into names that actual humans can read. Different compilers mangle differently, so the optional style argument lets you pick a demangling style that fits your compiler. By default the linker demangles — unless the environment variable COLLECT_NO_DEMANGLE is set. These options let you override that default whenever you want. 👑
-Ifile,--dynamic-linker=file— sets the name of the dynamic linker. This is only meaningful when you're generating dynamically linked ELF executables. The default dynamic linker is normally correct, so > do not use this unless you know what you are doing, bestie, for real. 😭--no-dynamic-linker— when producing an executable file, this omits the request for a dynamic linker to be used at load-time. Only meaningful for ELF executables that contain dynamic relocations, and it usually requires entry point code that's capable of processing those relocations. 🧚--embedded-relocs— similar to the--emit-relocsoption, except the relocs are stored in a target-specific section. Only supported by the BFIN, CR16 and M68K targets. 🎀--disable-multiple-abs-defs— do not allow multiple definitions with symbols included in filename invoked by-Ror--just-symbols. 🚫--fatal-warnings— treat all warnings as errors. 💀--no-fatal-warnings— restores the default behaviour.-w,--no-warnings— do not display any warning or error messages. This one overrides--fatal-warningsif that's been enabled. You'd use this when you already know the output binary won't work but you still need to create it anyway. Living dangerously, periodt. 🙈--force-exe-suffix— makes sure an output file has a.exesuffix.
Here's the deal: if a successfully built fully linked output file doesn't have a .exe or .dll suffix, this option forces the linker to copy the output file to one of the same name but with a .exe suffix. This is useful when you're using unmodified Unix makefiles on a Microsoft Windows host, because some versions of Windows straight up won't run an image unless it ends in .exe. 🪟
✨ more options, let's go ✨
--gc-sections— enable garbage collection of unused input sections. It gets ignored on targets that don't support it. 🌈--no-gc-sections— restores the default behaviour (i.e. not doing this garbage collection) by specifying it 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. 👀
So how does --gc-sections decide 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 get kept, and so do sections containing symbols referenced by dynamic objects. And note — when building shared libraries, the linker must assume that any visible symbol is referenced. Once that initial set of sections is determined, the linker recursively marks as used any section referenced by their relocations. See --entry, --undefined, and --gc-keep-exported. 🫶
You can also set this option when doing a partial link (enabled with the -r option). In that 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. 📝
And as a GNU extension, ELF input sections marked with the SHF_GNU_RETAIN flag will not be garbage collected. ✨
--print-gc-sections— list all sections removed by garbage collection. The listing is printed onstderr. Only effective if garbage collection has been enabled via the--gc-sectionsoption.--no-print-gc-sections— restores the default behaviour (of not listing the removed sections) when specified on the command line.--gc-keep-exported— when--gc-sectionsis enabled, this prevents garbage collection of unused input sections that contain global symbols having default or protected visibility. It's intended for executables where unreferenced sections would otherwise get garbage collected regardless of the external visibility of contained symbols. Note: this option has no effect when linking shared objects, since that's already the default behaviour there. Only supported for ELF format targets. 💜--print-output-format— prints the name of the default output format (maybe influenced by other command-line options). This is the string that would show up in anOUTPUT_FORMATlinker script command. 🎯--print-memory-usage— prints used size, total size, and used size of memory regions created with theMEMORYcommand. Super useful on embedded targets to get a quick view of how much free memory you've got. The output format has one headline and one line per region. It's both human readable and easily parsable by tools. Here's an example:
Memory region Used Size Region Size %age Used
ROM: 256 KB 1 MB 25.00%
RAM: 32 B 2 GB 0.00%Psst — if you actually wanna find out about the memory usage of the linker itself, then the --stats option is the one that does that. Not this one. 🍓
--help— print a summary of the command-line options on the standard output and exit. 🥰--target-help— print a summary of all target-specific options on the standard output and exit. ✨-Map=mapfile— print a link map to the file mapfile. See the description of the-Moption, above. If mapfile is just the character-, then the map gets written tostdout. 👑
Specifying a directory as mapfile causes the linker map to be written as a file inside that directory. Normally the name of the file inside the directory is computed as the basename of the output file with .map appended. But if the special character % is used, then it gets replaced by the full path of the output file. And additionally, if there are any characters after the % symbol, then .map will no longer be appended. Check it:
-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. 💀
And if the map file already exists, it will be overwritten by this operation. Gone. Poof. No takebacks. 🙈
--no-keep-memory—ldnormally optimizes for speed over memory usage by caching the symbol tables of input files in memory. This option tellsldto instead optimize for memory usage, by rereading the symbol tables as necessary. This may be required ifldruns out of memory space while linking a large executable. 😮💨--no-undefined,-z defs— report unresolved symbol references from regular object files. This happens even if the linker is creating a non-symbolic shared library. The switch--[no-]allow-shlib-undefinedcontrols 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.
--allow-multiple-definition,-z muldefs— normally when a symbol is defined multiple times, the linker reports a fatal error. These options allow multiple definitions, and the first definition will be used. 🎀--allow-shlib-undefined— allows undefined symbols in shared libraries.--no-allow-shlib-undefined— disallows them.
This switch is similar to --no-undefined, except 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: report errors for any undefined symbols referenced in shared libraries if the linker is being used to create an executable, but allow them if the linker is being used to create a shared library.
And why would you allow undefined symbol references in shared libraries specified at link time? Two reasons, bestie:
- A shared library specified at link time may not be the same as the one that's 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 just... 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. 🌈
...and there's more coming, don't you dare close the tab 💖
--error-handling-script=scriptname— okay bestie, if this option is provided then the linker will invokescriptnamewhenever 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.
The availability of this option is controlled by a configure time switch, so it may not be present in specific implementations. ✨
--no-undefined-version— Normally when a symbol has an undefined version, the linker will ignore it. This option disallows symbols with undefined version and a fatal error will be issued instead. 💅--default-symver— Create and use a default symbol version (the soname) for unversioned exported symbols. 🎀--default-imported-symver— Create and use a default symbol version (the soname) for unversioned imported symbols. 🦋--no-warn-mismatch— Normallyldwill 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 tellsldthat it should silently permit such possible errors. This option should only be used with care, in cases when you have taken some special action that ensures that the linker errors are inappropriate. 😭--no-warn-search-mismatch— Normallyldwill 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-archiveoption for subsequent archive files. Not allowed within a--start-lib/--end-liboption pair. 🚫--no-link-mapless— Reject archives that lack an index aka symbol map for all the subsequent archives referred on the command line. If such a file is encountered, a link error occurs. This is the traditional behavior. 📜--noinhibit-exec— Retain the executable output file whenever it is still usable. Normally, the linker will not produce an output file if it encounters errors during the link process; it exits without writing an output file when it issues any error whatsoever. 💚-nostdlib— Only search library directories explicitly specified on the command line. Library directories specified in linker scripts (including linker scripts specified on the command line) are ignored. 🙈--oformat=output-format—ldmay be configured to support more than one kind of object file. If yourldis configured this way, you can use the--oformatoption to specify the binary format for the output object file. Even whenldis configured to support alternative object formats, you don't usually need to specify this, asldshould be configured to produce as a default output format the most usual format on each machine.output-formatis a text string, the name of a particular format supported by the BFD libraries. (You can list the available binary formats withobjdump -i.) The script command"OUTPUT_FORMAT"can also specify the output format, but this option overrides it. 🌈--out-implib file— Create an import library infilecorresponding to the executable the linker is generating (eg. a DLL or ELF program). This import library (which should be called"*.dll.a"or"*.a"for DLLs) may be used to link clients against the generated executable; this behaviour makes it possible to skip a separate import library creation step (eg."dlltool"for DLLs). This option is only available for the PE and ELF targetted ports of the linker. 👑-pie,--pic-executable— Create a position independent executable. This is currently only supported on ELF platforms. Position independent executables are relocated by the dynamic linker to the virtual address the OS chooses for them, which can vary between invocations. They are markedET_DYNin the ELF file header, but 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 as they can be in a shared library. ✨-no-pie— Create a position dependent executable. This is the default. 🧍-qmagic— This option is ignored for Linux compatibility. 🐧-Qy— This option is ignored for SVR4 compatibility. 🧬--relax,--no-relax— An option with machine dependent effects. This option is only supported on a few targets.
On some platforms the --relax option performs target specific, global optimizations that become possible when the linker resolves addressing in the program, such as 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.
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. 🤷
--retain-symbols-file=filename— Retain only the symbols listed in the filefilename, discarding all others.filenameis simply a flat file, with one symbol name per line. This option is especially useful in environments (such as VxWorks) where a large global symbol table is accumulated gradually, to conserve run-time memory.
--retain-symbols-file does not discard undefined symbols, or symbols needed for relocations.
You may only specify --retain-symbols-file once in the command line. It overrides -s and -S. 🗂️
-rpath=dir— Add a directory to the runtime library search path. This is used when linking an ELF executable with shared objects. All-rpatharguments 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.
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.
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.
- Any directories specified by
-rpath-linkoptions. - Any directories specified by
-rpathoptions. The difference between-rpathand-rpath-linkis that directories specified by-rpathoptions are included in the executable and used at runtime, whereas the-rpath-linkoption is only effective at link time. Searching-rpathin this way is only supported by native linkers and cross linkers which have been configured with the--with-sysrootoption. - On an ELF system, for native linkers, if the
-rpathand-rpath-linkoptions were not used, search the contents of the environment variable"LD_RUN_PATH". - On SunOS, if the
-rpathoption was not used, search any directories specified using-Loptions. - For a native linker, search the contents of the environment variable
"LD_LIBRARY_PATH". - 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. 🔥
- For a linker targeting a Linux system: if the file
/etc/ld.so.confexists, then it's whatever list of directories lives inside that file. tiny plot twist tho — the path to this file gets prefixed with thesysrootvalue (if that's defined), and then with anyprefixstring if the linker was configured with the--prefix=<path>option. 🫶 - For a native linker on a FreeBSD system: any directories specified by the
_PATH_ELF_HINTSmacro, which is defined in theelf-hints.hheader file. ✨ - Any directories specified by a
SEARCH_DIRcommand inside a linker script that was given on the command line — including scripts specified by-T(but not-dT). 🙅♀️ - The default directories, which are normally
/liband/usr/lib. the classics. 👑 - Any directories specified by a plugin
LDPT_SET_EXTRA_LIBRARY_PATH. 🧚 - Any directories specified by a
SEARCH_DIRcommand in a default linker script.
Note however that on Linux based systems there's an extra little caveat, and it's giving main character energy: 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 a 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. yes bestie, it really does check. 💅
And if the required shared library is not found at all? The linker will issue a warning and continue with the link. no cap, it just keeps going. 😭
--section-ordering-file=script— this one is here to augment the current linker script with extra mapping of input sections to output sections. The file has to use the same syntax forSECTIONSas normal linker scripts do, but it should not do anything other than place input sections into output sections.@pxref{SECTIONS}🎀
There's a second constraint on the section ordering script: it can only reference output sections that are already defined by whichever linker script is currently in use (i.e. the default linker script, or a script specified on the command line). The benefit of the section ordering script, though, is that the input sections get mapped to the start of the output sections, so it can ensure the ordering of sections in the output section. For example, imagine 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 advantage of the section ordering file is that it can be used to order those sections that matter to the user without having to worry about any other sections, or memory regions, or anything else. so lowkey it's the "just the parts I care about" option. 🌸
-shared,-Bshareable— create a shared library. This is currently only supported onELF,XCOFFandSunOSplatforms. On SunOS, the linker will automatically create a shared library if the-eoption is not used and there are undefined symbols in the link. ✨--sort-common,--sort-common=ascending,--sort-common=descending— tellsldto sort the common symbols by alignment, in ascending or descending order, when it places them in the appropriate output sections. The symbol alignments considered are sixteen-byte or larger, eight-byte, four-byte, two-byte, and one-byte. This exists to prevent gaps between symbols due to alignment constraints. If no sorting order is specified, then descending order is assumed. 📐--sort-section=name— this one appliesSORT_BY_NAMEto all wildcard section patterns in the linker script. 🔤--sort-section=alignment— this one appliesSORT_BY_ALIGNMENTto all wildcard section patterns in the linker script. 📏--spare-dynamic-tags=count— specifies the number of empty slots to leave in the.dynamicsection of ELF shared objects. Empty slots may be needed by post processing tools, such as the prelinker. The default is5. 🎁--split-by-file[=size]— similar to--split-by-reloc, but creates a new output section for each input file when size is reached. size defaults to a size of1if not given. ✂️--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. This is useful when generating huge relocatable files for downloading into certain real time kernels with theCOFFobject file format; since COFF cannot represent more than65535relocations in a single section. Note that this will fail to work with object file formats which do not support arbitrary sections. The linker will not split up individual input sections for redistribution, so if a single input section contains more than count relocations, one output section will contain that many relocations. count defaults to a value of32768. 😮💨--stats[=filename]— compute and display statistics about the operation of the linker, such as execution time and memory usage. the receipts. 🧾
If the optional filename argument is not supplied, then only basic information is reported, and it gets sent to the standard error output stream. If the filename argument is supplied, then extended information is written to the named file. If filename is set to just the - symbol, then the extended information is sent 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 this will be used as the name of a file into which the information should be recorded. Otherwise the information will be sent to the standard output stream. Using the environment variable lets stats be recorded 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 it should not be assumed that the overall resources used by the linker is the sum of the resources used by the individual phases. fr fr, do not do that math. 🚫
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 indentify 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
Stats: write 116493 0 0 0 48096--no-stats— disables the reporting of usage statistics, should it have been enabled via the--statscommand line option or theLD_STATSenvironment variable. the undo button bestie. ↩️--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 byCOFF/PEbased 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 ofldis different in some ways from the output of some existing linker. This switch requestsldto use the traditional format instead. 🕰️
For example, on SunOS, ld combines duplicate entries in the symbol string table. This can reduce the size of an output file with full debugging information by over 30 percent. Unfortunately, the SunOS dbx program can not read the resulting program (gdb has no trouble). The --traditional-format switch tells ld to not combine duplicate entries. 💀
--section-start=sectionname=org— drop a section in the output file at the absolute address org gave you. Use it as many times as you want, bestie, once per section, all on the same command line. org has to be a single hexadecimal integer, and for compatibility with other linkers you can skip the leading0xyou'd normally write for hex. Heads up: there must be no white space between sectionname, the equals sign (=), and org. Not even one. Not one sneaky little space. 💅--image-base=org— with ELF, it's literally the same as-Ttext-segment, and both of them effectively set the base address of the ELF executable. With PE, you use the value as the base address of your program or dll — aka the lowest memory location that gets used when your program or dll is loaded. To cut down on relocating and to make your dlls faster, each one should have a unique base address and not overlap any other dll. Default is0x400000for executables and0x10000000for dlls. manifesting non-overlapping dlls for u ✨-Tbss=org-Tdata=org-Ttext=org— same as--section-start, except the sectionname is.bss,.dataor.textrespectively. the holy trinity of segments fr fr-Ttext-segment=org— when you're creating an ELF executable, this sets the address of the first byte of the first segment. And note: when-pieis used together with-Ttext-segment=org, the output executable gets markedET_EXEC, so that the address of the first byte of the text segment is guaranteed to be org at run time. guaranteed bestie, no cap-Trodata-segment=org— when you're making an ELF executable or shared object for a target where the read-only data lives in its own segment, separate from the executable text, this sets the address of the first byte of the read-only data segment. her own lil segment 🎀-Tldata-segment=org— when you're creating an ELF executable or shared object for x86-64 medium memory model, this sets the address of the first byte of the ldata segment.--unresolved-symbols=method— this one decides how we're handling unresolved symbols. There are four possible values for method:ignore-all— do not report any unresolved symbols. living in denial, iconicreport-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 is lowkey useful when you're creating a dynamic binary and you already know that all the shared libraries it should be referencing are 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 drops an error message for each reported unresolved symbol, but --warn-unresolved-symbols can change that to a warning instead. error ➡️ warning, a glow down but a vibe
--dll-verbose--verbose[=NUMBER]— shows you the version number forldand lists the linker emulations that are supported. Displays which input files can and cannot be opened. Displays the linker script being used by the linker. And if the optional NUMBER argument is> 1, plugin symbol status gets displayed too. full transparency mode bestie 🔍--version-script=version-scriptfile— names a version script for the linker. Typically used when creating shared libraries, to specify extra info about the version hierarchy for the library you're making. This option is only fully supported on ELF platforms that support shared libraries — seeVERSION. It's partially supported on PE platforms, which can use version scripts to filter symbol visibility in auto-export mode: any symbols marked local in the version script will not be exported. local symbols stay home, we respect it--warn-common— warns you when a common symbol gets combined with another common symbol, or with a symbol definition. Unix linkers allow this kinda sloppy practice, but linkers on some other operating systems do not. This option lets you find potential problems from combining global symbols. Unfortunately, some C libraries use this practice, so you may get warnings about symbols in the libraries as well as in your own programs. not your fault bestie, the libs are messy too 😭
There are three kinds of global symbols, illustrated here 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 must be either a definition or a common symbol for the variable somewhere.
int i;A common symbol. If there are only (one or more) common symbols for a variable, it goes in the uninitialized data area of the output file. The linker merges multiple common symbols for the same variable into a single symbol. If they are of different sizes, it picks the largest size. The linker turns a common symbol into a declaration, if there is a definition of the same variable.
The --warn-common option can produce five kinds of warnings. Each warning 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.
- 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- Turning a common symbol into a reference, because a later definition for the symbol is encountered. This is the same as the previous case, except that the symbols are encountered in a different order.
<file>(<section>): warning: definition of `<symbol>'
overriding common
<file>(<section>): warning: common is here- 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- 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- Merging a common symbol with a previous smaller common symbol. This is the same as the previous case, except that the symbols are encountered in a different order.
<file>(<section>): warning: common of `<symbol>'
overriding smaller common
<file>(<section>): warning: smaller common is here--warn-constructors— warns you if any global constructors are used. This is only useful for a few object file formats. For formats like COFF or ELF, the linker literally cannot detect the use of global constructors. it's giving "I tried my best" 💀--warn-execstack--warn-execstack-objects--no-warn-execstack— on ELF platforms the linker may generate warning messages if it's asked to create an output file that contains an executable stack. There are three possible states:- Do not generate any warnings.
- Always generate warnings, even if the executable stack is requested via the
-z execstackcommand line option. - Only generate a warning if an object file requests an executable stack, but not if the
-z execstackoption is used.
The default state depends on how the linker was configured when it was built. --no-warn-execstack always puts the linker into the no-warnings state. --warn-execstack puts the linker into the warn-always state. --warn-execstack-objects 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. hand-written asm girlies, check ur notes section 🫶
--error-execstack--no-error-execstack— if the linker is about to generate a warning message about an executable stack, then--error-execstackwill instead change that warning into an error. Note: this option does not change the linker's execstack warning generation state. Use--warn-execstackor--warn-execstack-objectsto set a specific warning state.
The --no-error-execstack option restores the default behaviour of generating warning messages. back to normal, we love a reset
--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. 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 to be able to address all possible constants. This option causes a warning to be issued whenever this case occurs. Alpha girlies stay winning 👑--warn-once— only warn once for each undefined symbol, rather than once per module which refers to it. we're not doing spam bestie--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. Such a segment represents a potential security vulnerability. like, actually dangerous bestie, not a vibe 💀 In addition, warnings will be 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.
Okay so these warnings are on by default — like, they come pre-loaded 💅 — but bestie you can turn them off with --no-warn-rwx-segments and then re-enable them with --warn-rwx-segments. The choice is yours, the power is yours ✨
--error-rwx-segments,--no-error-rwx-segments— so if the linker is about to give you a warning about an executable, writeable segment, or an executable TLS segment, then--error-rwx-segmentsupgrades that lil warning into a full-on ERROR 💀 and--no-error-rwx-segmentsputs it back to the default vibe of just warning you. Note:--error-rwx-segmentsdoes not by itself turn on warnings about these segments — those warnings are either enabled by default (if the linker was configured that way) or you get them via the--warn-rwx-segmentscommand line option. Two separate things, don't mix them up 🫶--warn-section-align— yells at you if the address of an output section gets changed because of alignment. Usually the alignment is set by an input section. The address only changes if it wasn't explicitly specified — like, if the"SECTIONS"command doesn't give a start address for the section.--warn-textrel— warns you if the linker addsDT_TEXTRELto a position-independent executable or shared object. ✨--warn-alternate-em— warns you if an object has alternate ELF machine code. iykyk 🌸--warn-unresolved-symbols— if the linker is about to report an unresolved symbol (peep the--unresolved-symbolsoption), it normally gives you an error. This option makes it give you a warning instead. Softer, gentler 🧚--error-unresolved-symbols— this restores the linker's default behaviour of generating errors when it's reporting unresolved symbols. Back to being strict, no cap 🔥--whole-archive— for each archive mentioned on the command line after the--whole-archiveoption, include every object file in the archive in the link, instead of searching the archive for just the required object files. This is normally used to turn an archive file into a shared library, forcing every single object to be included in the resulting shared library. This option may be used more than once. 💅
This option is not allowed within a --start-lib/--end-lib option pair. 🚫
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. 🙈
--link-mapless— accepts archives that lack an index aka symbol map for all the subsequent archives referred on the command line. If it's missing, such an index is made internally on the fly, at a performance cost. This is the default. 😌--wrap=symbol — use a wrapper function for symbol. Any undefined reference to symbol will be resolved to"__wrap_symbol". Any undefined reference to"__real_symbol"will be resolved to symbol.
This can be used to provide a wrapper for a system function. The wrapper function should be called "__wrap_symbol". If it wishes to call the system function, it should call "__real_symbol".
Here is a trivial example:
void *
__wrap_malloc (size_t c)
{
printf ("malloc called with %zu\n", c);
return __real_malloc (c);
}If you link other code with this file using --wrap malloc, then all calls to "malloc" will call the function "__wrap_malloc" instead. The call to "__real_malloc" in "__wrap_malloc" will call the real "malloc" function.
You may wish to provide a "__real_malloc" function as well, so that links without the --wrap option will succeed. If you do this, you should not put the definition of "__real_malloc" in the same file as "__wrap_malloc"; if you do, the assembler may resolve the call before the linker has a chance to wrap it to "malloc". 🫠
Only undefined references are replaced by the linker. So, translation unit internal references to symbol are not resolved to "__wrap_symbol". In the next example, the call to "f" in "g" is not resolved to "__wrap_f".
int
f (void)
{
return 123;
}
int
g (void)
{
return f();
}--eh-frame-hdr,--no-eh-frame-hdr— request (--eh-frame-hdr) or suppress (--no-eh-frame-hdr) the creation of".eh_frame_hdr"section and ELFPT_GNU_EH_FRAMEsegment header. ✨--no-ld-generated-unwind-info— request creation of".eh_frame"unwind info for linker generated code sections like PLT. This option is on by default if linker generated unwind info is supported.--discard-sframe— discard".sframe"stack trace info from the output. This option also prohibits the creation of SFrame stack trace data for linker generated code sections like PLT. This option is off by default.--enable-new-dtags,--disable-new-dtags— this linker can create the new dynamic tags in ELF. But the older ELF systems may not understand them 😭. If you specify--enable-new-dtags, the new dynamic tags will be created as needed and older dynamic tags will be omitted. If you specify--disable-new-dtags, no new dynamic tags will be created. By default, the new dynamic tags are not created. Note that those options are only available for ELF systems. 🐧--hash-size=number — set the default size of the linker's hash tables to a prime number close to number. Increasing this value can reduce the length of time it takes the linker to perform its tasks, at the expense of increasing the linker's memory requirements. Similarly reducing this value can reduce the memory requirements at the expense of speed. The default value is4051under normal circumstances and1021if the--reduce-memory-overheadscommand line option is used. Tradeoffs, babe 💅--hash-style=style — set the type of linker's hash table(s). style can be either"sysv"for classic ELF".hash"section,"gnu"for new style GNU".gnu.hash"section or"both"for both the classic ELF".hash"and new style GNU".gnu.hash"hash tables. The default depends upon how the linker was configured, but for most Linux based systems it will 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 options control how DWARF debug sections are compressed using zlib.
--compress-debug-sections=none doesn't compress DWARF debug sections. --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 rather than renaming them it sets the SHF_COMPRESSED flag in the sections' headers.
The --compress-debug-sections=zlib option is an alias for --compress-debug-sections=zlib-gabi. 💫
--compress-debug-sections=zstd compresses DWARF debug sections using zstd.
Note that 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 are copied into the output binary. 🦋
The default compression behaviour varies depending upon the target involved and the configure options used to build the toolchain. The default can be determined by examining the output from the linker's --help option. 🔍
--reduce-memory-overheads— this option reduces memory requirements at ld runtime, at the expense of linking speed. This was introduced to select the old O(n^2) algorithm for link map file generation, rather than the new O(n) algorithm which uses about 40% more memory for symbol storage.
Another effect of the switch is to set the default hash table size to 1021, which again saves memory at the cost of lengthening the linker's run time. This is not done however if the --hash-size switch has been used.
The --reduce-memory-overheads switch may be also be used to enable other tradeoffs in future versions of the linker. 🔮
--max-cache-size=size — ld normally caches the relocation information and symbol tables of input files in memory with the unlimited size. This option sets the maximum cache size to size. Note — if the--no-keep-memorycommand line option has been used then the linker acts as if the maximum cache size has been set to0— ie 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"to use 128 random bits;"sha1"to use a 160-bit SHA1 hash,"md5"to use a 128-bit MD5 hash, or"xx"to use a 128-bit XXHASH on the normative parts of the output contents; or"0xhexstring"to use a chosen bit string specified as an even number of hexadecimal digits ("-"and":"characters between digit pairs are ignored). If style is omitted,"sha1"is used. ✨
The "md5", "sha1", and "xx" styles produces 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— bestie, this one asks the linker to make a.note.packageELF note section for you ✨ and the contents of that note are in JSON format, exactly per the package metadata specification. Wanna read the spec? It's right here:https://systemd.io/ELF_PACKAGE_METADATA/💖 The JSON argument supports percent-encoding, and it also supports the following%[string]encoding (where string is the name in HTML's Named Character References):%[comma]for,,%[lbrace]for{,%[quot]for",%[rbrace]for}, and%[space]for the space character 🌸 And if the JSON argument is missing or empty? Then this disables the creation of the metadata note, but only if one had been enabled by an earlier occurrence of the--package-metadataoption 👀 Also, if the linker has been built with libjansson, then the JSON string gets validated, periodt.
The 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. And on top of that, the linker fully supports the standard *.def files, which may be specified on the linker command line just like an object file (in fact, it should come before the archives it exports symbols from, so that they get linked in, same as a normal object file, iykyk 💅).
In addition to the options common to all targets, the PE linker also supports extra command-line options that are specific to the PE target 🌈 Options that take values may be separated from their values by either a space or an equals sign.
--add-stdcall-alias— if you give this, symbols with a stdcall suffix (@nn) will be exported as-is and also with the suffix stripped 💅 [This option is specific to PE targeted ports of the linker]--base-filefile — use file as the name of a file in which to save the base addresses of all the relocations needed for generating DLLs withdlltool. [This option is specific to PE targeted ports of the linker]--dll— create a DLL instead of a regular executable 🎀 You may also use-sharedor specify aLIBRARYin a given.deffile. [This option is specific to PE targeted ports of the linker]--enable-long-section-names,--disable-long-section-names— so the PE variants of the COFF object format add an extension that permits section names longer than eight characters, which is the normal limit for COFF ✨ By default, these names are only allowed in object files, because fully-linked executable images do not carry the COFF string table required to support the longer names. But 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, like file viewers and dumpers 💀 However, GDB relies on the use of PE long section names to find Dwarf-2 debug information sections in an executable image at runtime, and so if neither option is specified on the command-line,ldwill 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 specific to PE targeted ports of the linker]--enable-stdcall-fixup,--disable-stdcall-fixup— if the link finds a symbol it can't resolve, it will attempt to do "fuzzy linking" by looking for another defined symbol that differs only in the format of the symbol name (cdecl vs stdcall) and will resolve that symbol by linking to the match 🔍 For example, the undefined symbol_foomight be linked to the function_foo@12, or the undefined symbol_bar@16might be linked to the function_bar. When the linker does this, it prints a warning, since it normally should have failed to link — but sometimes import libraries generated from third-party dlls may need this feature to be usable 💜 If you specify--enable-stdcall-fixup, this feature is fully enabled and warnings are not printed. If you specify--disable-stdcall-fixup, this feature is disabled and such mismatches are considered to be errors 🚨 [This option is specific to PE targeted ports 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 🌸 By this option it's possible to disable/enable the default underscore symbol-prefix. [This option is specific to PE targeted ports of the linker]--export-all-symbols— if given, all global symbols in the objects used to build a DLL will be exported by the DLL 👑 Note that this is the default if there otherwise wouldn't be any exported symbols. When symbols are explicitly exported via DEF files or implicitly exported via function attributes, the default is to not export anything else unless this option is given. Note that the symbolsDllMain@12,DllEntryPoint@0,DllMainCRTStartup@12, andimpure_ptrwill not be automatically exported 🙅 Also, symbols imported from other DLLs will not be re-exported, and neither will symbols specifying the DLL's internal layout, like those beginning with_head_or ending with_iname💅 In addition, no symbols fromlibgcc,libstd++,libmingw32, orcrtX.owill be exported. Symbols whose names begin with__rtti_or__builtin_will not be exported either, to help with C++ DLLs. And finally, there's an extensive list of cygwin-private symbols that are not 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, andenviron. [This option is specific to PE targeted ports of the linker]--exclude-symbolssymbol,symbol,... — specifies a list of symbols which should not be automatically exported 🚫 The symbol names may be delimited by commas or colons. [This option is specific to PE targeted ports of the linker]--exclude-all-symbols— specifies no symbols should be automatically exported, like, none, zero, nada 💀 [This option is specific to PE targeted ports of the linker]--file-alignment— specify the file alignment 📐 Sections in the file will always begin at file offsets which are multiples of this number. This defaults to512. [This option is specific to PE targeted ports of the linker]--heapreserve,--heapreserve,commit — specify the number of bytes of memory to reserve (and optionally commit) to be used as heap for this program 🌸 The default is1MBreserved,4Kcommitted. [This option is specific to PE targeted ports of the linker]--kill-at— if given, the stdcall suffixes (@nn) will be stripped from symbols before they are exported ✂️ [This option is specific to PE targeted ports of the linker]--large-address-aware— if given, the appropriate bit in theCharacteristicsfield of the COFF header is set to indicate that this executable supports virtual addresses greater than 2 gigabytes 👀 This should be used in conjunction with the/3GBor/USERVA=valuemegabytes switch in the[operating systems]section of theBOOT.INI. Otherwise, this bit has no effect. [This option is specific to the i386 PE targeted port of the linker]--disable-large-address-aware— reverts the effect of a previous--large-address-awareoption ↩️ This is useful if--large-address-awareis 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 the i386 PE targeted port of the linker]--major-image-versionvalue — sets the major number of theimage version🎀 Defaults to1. [This option is specific to PE targeted ports of the linker]--major-os-versionvalue — sets the major number of theos version. Defaults to4. [This option is specific to PE targeted ports of the linker]--major-subsystem-versionvalue — sets the major number of thesubsystem version. Defaults to4. [This option is specific to PE targeted ports of the linker]--minor-image-versionvalue — sets the minor number of theimage version✨ Defaults to0. [This option is specific to PE targeted ports of the linker]--minor-os-versionvalue — sets the minor number of theos version. Defaults to0. [This option is specific to PE targeted ports of the linker]--minor-subsystem-versionvalue — sets the minor number of thesubsystem version. Defaults to0. [This option is specific to PE targeted ports of the linker]--output-deffile — 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 withdlltoolor may be used as a reference to automatically or implicitly exported symbols. [This option is specific to PE targeted ports 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-baseargument 🌈 By using a hash generated from the dllname to create unique image bases for each DLL, in-memory collisions and relocations which can delay program execution are avoided 👑 [This option is specific to PE targeted ports 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 PE targeted ports of the linker]--dll-search-prefixstring — when linking dynamically to a dll without an import library, search for<string><basename>.dllin preference tolib<basename>.dll🔍 This behaviour allows easy distinction between DLLs built for the varioussubplatforms: native, cygwin, uwin, pw, etc. For instance, cygwin DLLs typically use--dll-search-prefix=cyg. [This option is specific to PE targeted ports of the linker]--enable-auto-import— bestie, this one does the sophisticated linking: it wires"_symbol"up to__imp__symbolfor DATA imports coming from DLLs. Which means you can just... bypass thedllimportmechanism on the user side entirely, AND reference unmangled symbol names. [This option is specific to PE targeted ports of the linker]
Okay so real talk — the following remarks pertain to the original implementation of the feature and are obsolete nowadays 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 not conform to the PE-COFF format specification published by Microsoft.
Note - use of the'auto-import'extension will also cause read only data which would normally be placed into the.rdatasection to be placed into the.datasection instead. This is in order to work around a problem with consts that is described here:http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
Using 'auto-import' generally will 'just work' -- but sometimes you may see this message:
"variable '<var>' can't be auto-imported. Please read the
documentation for ld's "--enable-auto-import" for details."This message occurs when some (sub)expression accesses an address ultimately given by the sum of two constants (Win32 import tables only allow one). Instances where this may occur include accesses to member fields of struct variables imported from a DLL, as well as using a constant index into an array variable imported from a DLL. Any multiword variable (arrays, structs, long long, etc) may trigger this error condition. However, regardless of the exact data type of the offending exported variable, ld will always detect it, issue the warning, and exit. iconic of it tbh
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-relocswitch. This leaves the task of adjusting references in your client code for runtime environment, so this method works only when runtime environment supports this feature. - A second solution is to force one of the
'constants'to be a variable -- that is, unknown and un-optimizable at compile time. For arrays, there are two possibilities: a) make the indexee (the array's address) a variable, or b) make the'constant'index a variable. Thus:
extern type extern_array[];
extern_array[1] -->
{ volatile type *t=extern_array; t[1] }or
extern type extern_array[];
extern_array[1] -->
{ volatile int t=1; extern_array[t] }For structs (and most other multiword data types) the only option is to make the struct itself (or the long long, or the ...) variable:
extern struct s extern_struct;
extern_struct.field -->
{ volatile struct s *t=&extern_struct; t->field }or
extern long long extern_ll;
extern_ll -->
{ volatile long long * local_ll=&extern_ll; *local_ll }- A third method of dealing with this difficulty is to abandon
'auto-import'for the offending symbol and mark it with"__declspec(dllimport)". However, in practice that requires using compile-time#defines to indicate whether you are building a DLL, building client code that will link to the DLL, or merely building/linking to a static library. In making the choice between the various methods of resolving the'direct address with constant offset'problem, you should consider typical real-world usage:
Original:
--foo.h
extern int arr[];
--foo.c
#include "foo.h"
void main(int argc, char **argv){
printf("%d\n",arr[1]);
}Solution 1:
--foo.h
extern int arr[];
--foo.c
#include "foo.h"
void main(int argc, char **argv){
/* This workaround is for win32 and cygwin; do not "optimize" */
volatile int *parr = arr;
printf("%d\n",parr[1]);
}Solution 2:
--foo.h
/* Note: auto-export is assumed (no __declspec(dllexport)) */
#if (defined(_WIN32) || defined(__CYGWIN__)) && \
!(defined(FOO_BUILD_DLL) || defined(FOO_STATIC))
#define FOO_IMPORT __declspec(dllimport)
#else
#define FOO_IMPORT
#endif
extern FOO_IMPORT int arr[];
--foo.c
#include "foo.h"
void main(int argc, char **argv){
printf("%d\n",arr[1]);
}- A fourth way to avoid this problem is to re-code your library to use a functional interface rather than a data interface for the offending variables (e.g.
set_foo()andget_foo()accessor functions).
--disable-auto-import— do not attempt to do sophisticated linking of"_symbol"to__imp__symbolfor DATA imports from DLLs. [This option is specific to PE targeted ports of the linker]--enable-runtime-pseudo-reloc— if your code contains expressions described in the--enable-auto-importsection, that is, DATA imports from DLL with non-zero offset, this switch will create a vector of'runtime pseudo relocations'which can be used by runtime environment to adjust references to such data in your client code. [This option is specific to PE targeted ports 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 PE targeted ports of the linker]--enable-extra-pe-debug— show additional debug info related to auto-import symbol thunking. [This option is specific to PE targeted ports of the linker]--section-alignment— sets the section alignment. Sections in memory will always begin at addresses which are a multiple of this number. Defaults to0x1000. [This option is specific to PE targeted ports of the linker]--stack reserve--stack reserve,commit— specify the number of bytes of memory to reserve (and optionally commit) to be used as stack for this program. The default is2MBreserved,4Kcommitted. [This option is specific to PE targeted ports of the linker]--subsystem which--subsystem which:major--subsystem which:major.minor— specifies the subsystem under which your program will execute. The legal values for which are"native","windows","console","posix", and"xbox". You may optionally set the subsystem version also. Numeric values are also accepted for which. [This option is specific to PE targeted ports of the linker]
The following options set flags in the "DllCharacteristics" field of the PE file header: [These options are specific to PE targeted ports of the linker]
--high-entropy-va--disable-high-entropy-va— image is compatible with 64-bit address space layout randomization (ASLR). This option is enabled by default for 64-bit PE images in MinGW targets.
This option also implies --dynamicbase and --enable-reloc-section. [This options is specific to 64-bit PE targeted ports of the linker]
--dynamicbase--disable-dynamicbase— the image base address may be relocated using address space layout randomization (ASLR). This feature was introduced with MS Windows Vista. This option is enabled by default for MinGW targets but can be disabled via the--disable-dynamicbaseoption. This option also implies--enable-reloc-section.--forceinteg--disable-forceinteg— code integrity checks are enforced. This option is disabled by default.--nxcompat--disable-nxcompat— the image is compatible with the Data Execution Prevention. This feature was introduced with MS Windows XP SP2. The option is enabled by default for MinGW targets.--no-isolation--disable-no-isolation— although the image understands isolation, do not isolate the image. This option is disabled by default.--no-seh--disable-no-seh— the image does not use SEH. No SE handler may be called from this image. This option is disabled by default.--no-bind--disable-no-bind— do not bind this image. This option is disabled by default.--wdmdriver--disable-wdmdriver— the driver uses the MS Windows Driver Model. This option is disabled by default.--tsaware--disable-tsaware— the image is Terminal Server aware. This option is disabled by default.--insert-timestamp--no-insert-timestamp— insert a real timestamp into the image. This is the default behaviour as it matches legacy code and it means that the image will work with other, proprietary tools. The problem with this default is that it will result in slightly different images being produced each time the same sources are linked. The option--no-insert-timestampcan be used to insert a zero value for the timestamp, this ensuring that binaries produced from identical sources will compare identically. reproducible builds bestie!! we love to see it ✨
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 is loaded at a different image base than specified in the PE header. This option is enabled by default.
The C6X uClinux target uses a binary format called DSBT to support shared libraries. Each shared library in the system needs to have a unique index; all executables use an index of 0. okay that's actually a cute little system ngl
--dsbt-size size— this option sets the number of entries in the DSBT of the current executable or shared library to size. The default is to create a table with64entries.--dsbt-index index— this option sets the DSBT index of the current executable or shared library to index. The default is0, which is appropriate for generating executables. If a shared library is generated with a DSBT index of0, the"R_C6000_DSBT_INDEX"relocs are copied into the output file.--no-merge-exidx-entries— this one turns OFF the merging of adjacent exidx entries in frame unwind info. bye bestie, no smooshing today 💅--branch-stub— enables linker branch relaxation by inserting branch stub sections when that's needed to extend the range of branches. Lowkey you probably don't need it tho, because C-SKY supports branch and call instructions that can reach the whole memory range anyway, and branch relaxation is normally the compiler's or assembler's whole job.--stub-group-size=N— this gives you finer control over linker branch stub creation. It sets the max size of a group of input sections that one stub section can handle. A negativeNputs stub sections after their branches, while a positive value lets stub sections show up either before or after the branches. Values of1or-1mean "linker bestie, you pick suitable defaults" ✨
The 68HC11 and 68HC12 linkers have their own special options for controlling memory bank switching mapping and trampoline code generation 👑
--no-trampoline— disables generation of trampoline. By default a trampoline gets generated for each far function called using a"jsr"instruction (which happens when a pointer to a far function is taken).--bank-windowname — tells the linker the name of the memory region in the MEMORY specification that describes the memory bank window. The linker then uses that region's definition to compute paging and addresses within the memory window.
The following options control GOT generation when linking for 68K targets:
--got=type — tells the linker which GOT generation scheme to use. type should be one ofsingle,negative,multigotortarget. For more info, go read the Info entry for ld, iykyk 📖
These next ones control microMIPS instruction generation and branch relocation checks for ISA mode transitions when linking for MIPS targets 🧚
--insn32--no-insn32
These control which microMIPS instructions get used in code the linker generates — like stuff 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 fair game, 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 runs and losing an ISA mode transition produces an error 🚨
--compact-branches--no-compact-branches
These control the generation of compact instructions by the linker in the PLT entries for MIPS R6.
For the pdp11-aout target, three variants of the output format can be produced, picked by the following options. The default variant for pdp11-aout is --omagic, whereas for other targets --nmagic is the default. The --imagic option is defined only for the pdp11-aout target, while the others are described here as they apply to the pdp11-aout target. periodt 💅
-N,--omagic— marks the output as"OMAGIC"(0407) in the a.out header, signalling 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, signalling 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, signalling 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 location0. The-zoption selected this format in 2.11BSD. This option creates a separate executable format 🌈--no-omagic— equivalent to--nmagicfor pdp11-aout.
✨ ENVIRONMENT ✨
You can change how ld behaves with the environment variables "GNUTARGET", "LDEMULATION" and "COLLECT_NO_DEMANGLE" 🫶
"GNUTARGET" determines the input-file object format if you don't use -b (or its synonym --format). Its value should be one of the BFD names for an input format. If there's no "GNUTARGET" in the environment, ld uses the natural format of the target. If "GNUTARGET" is set to "default" then BFD tries to discover the input format by examining binary input files; this method often succeeds, but there are potential ambiguities, since there's no way to ensure 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 get 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, especially the default linker script. You can list the available emulations with the --verbose or -V options. If the -m option isn't used, and the "LDEMULATION" environment variable isn't defined, the default emulation depends on how the linker was configured.
Normally, the linker defaults to demangling symbols. However, if "COLLECT_NO_DEMANGLE" is set in the environment, then it defaults 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 gets 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 gets sent to the standard output stream 📊
🌈 SEE ALSO 🌈
ar(1), nm(1), objcopy(1), objdump(1), readelf(1) and the Info entries for binutils and ld 👯♀️
💖 COPYRIGHT 💖
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".
okay bestie that's the whole page, we made it to the end and we ate fr fr 💅✨ This one's from binutils-2.47, dated 2026-08-11, and yeah, it's the LD(1) page 🎀 go forth and link things, you main character 👑💖
📦 where this page comes from
- arch rolling: binutils 2.47-4 · GPL-2.0-or-later AND GPL-3.0-or-later AND LGPL-2.0-or-later AND LGPL-3.0-or-later AND GFDL-1.3 AND FSFAP
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on : a language model's rewrite of the original, under its terms