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1 .\" Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2 .\" See https://llvm.org/LICENSE.txt for license information.
3 .\" SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4 .\"
5 .\" This man page documents only lld's ELF linking support, obtained originally
6 .\" from FreeBSD.
7 .Dd Jul 25, 2023
8 .Dt LD.LLD 1
9 .Os
10 .Sh NAME
11 .Nm ld.lld
12 .Nd ELF linker from the LLVM project
13 .Sh SYNOPSIS
14 .Nm ld.lld
15 .Op Ar options
16 .Ar objfile ...
17 .Sh DESCRIPTION
18 A linker takes one or more object, archive, and library files, and combines
19 them into an output file (an executable, a shared library, or another object
20 file).
21 It relocates code and data from the input files and resolves symbol
22 references between them.
23 .Pp
24 .Nm
25 is a drop-in replacement for the GNU BFD and gold linkers.
26 It accepts most of the same command line arguments and linker scripts
27 as GNU linkers.
28 .Pp
29 .Nm
30 currently supports i386, x86-64, ARM, AArch64, LoongArch, PowerPC32,
31 PowerPC64, MIPS32, MIPS64, RISC-V, AMDGPU, Hexagon and SPARC V9 targets.
32 .Nm
33 acts as a Microsoft link.exe-compatible linker if invoked as
34 .Nm lld-link
35 and as macOS's ld if invoked as
36 .Nm ld.ld64.
37 All these targets are always supported however
38 .Nm
39 was built, so you can always use
40 .Nm
41 as a native linker as well as a cross linker.
42 .Sh OPTIONS
43 Many options have both a single-letter and long form.
44 When using the long form options other than those beginning with the
45 letter
46 .Cm o
47 may be specified using either one or two dashes preceding the option name.
48 Long options beginning with
49 .Cm o
50 require two dashes to avoid confusion with the
51 .Fl o Ar path
52 option.
53 .Pp
54 .Bl -tag -width indent
55 .It Fl -allow-multiple-definition
56 Do not error if a symbol is defined multiple times.
57 The first definition will be used.
58 .It Fl -allow-shlib-undefined
59 Allow unresolved references in shared libraries.
60 This option is enabled by default when linking a shared library.
61 .It Fl -apply-dynamic-relocs
62 Apply link-time values for dynamic relocations.
63 .It Fl -as-needed
64 Only set
65 .Dv DT_NEEDED
66 for shared libraries if used.
67 .It Fl -auxiliary Ns = Ns Ar value
68 Set the
69 .Dv DT_AUXILIARY
70 field to the specified name.
71 .It Fl -Bdynamic , Fl -dy
72 Link against shared libraries.
73 .It Fl -Bstatic , Fl -static , Fl -dn
74 Do not link against shared libraries.
75 .It Fl Bno-symbolic
76 Don't bind default visibility defined symbols locally for
77 .Fl shared
78 (default).
79 .It Fl Bsymbolic
80 Bind default visibility defined symbols locally for
81 .Fl shared.
82 Also set the
83 .Dv DF_SYMBOLIC
84 flag.
85 .It Fl Bsymbolic-non-weak
86 Bind default visibility defined STB_GLOBAL symbols locally for
87 .Fl shared.
88 .It Fl Bsymbolic-functions
89 Bind default visibility defined function symbols locally for
90 .Fl shared.
91 .It Fl Bsymbolic-non-weak-functions
92 Bind default visibility defined STB_GLOBAL function symbols locally for
93 .Fl shared.
94 .It Fl --be8
95 Write a Big Endian ELF File using BE8 format(AArch32 only)
96 .It Fl -build-id Ns = Ns Ar value
97 Generate a build ID note.
98 .Ar value
99 may be one of
100 .Cm fast ,
101 .Cm md5 ,
102 .Cm sha1 ,
103 .Cm tree ,
104 .Cm uuid ,
105 .Cm 0x Ns Ar hex-string ,
106 and
107 .Cm none .
108 .Cm tree
109 is an alias for
110 .Cm sha1 .
111 Build-IDs of type
112 .Cm fast ,
113 .Cm md5 ,
114 .Cm sha1 ,
115 and
116 .Cm tree
117 are calculated from the object contents.
118 .Cm fast
119 is not intended to be cryptographically secure.
120 .It Fl -build-id
121 Synonym for
122 .Fl -build-id Ns = Ns Cm sha1 .
123 .It Fl -call-graph-profile-sort Ns = Ns Ar algorithm
124 .Ar algorithm
125 may be:
126 .Pp
127 .Bl -tag -width 2n -compact
128 .It Cm none
129 Ignore call graph profile.
130 .It Cm hfsort
131 Use hfsort.
132 .It Cm cdsort
133 Use cdsort (default).
134 .El
135 .Pp
136 .It Fl -color-diagnostics Ns = Ns Ar value
137 Use colors in diagnostics.
138 .Ar value
139 may be one of
140 .Cm always ,
141 .Cm auto ,
142 and
143 .Cm never .
144 .Cm auto
145 enables color if and only if output is to a terminal.
146 .It Fl -color-diagnostics
147 Alias for
148 .Fl -color-diagnostics Ns = Ns Cm auto .
149 .It Fl -compress-debug-sections Ns = Ns Ar value
150 Compress DWARF debug sections.
151 The sections remain uncompressed if compressed content would be larger.
152 .Cm value
153 may be
154 .Pp
155 .Bl -tag -width 2n -compact
156 .It Cm none
157 No compression.
158 .It Cm zlib
159 The default compression level is 1 (fastest) as the debug info usually
160 compresses well at that level.
161 .It Cm zstd
162 Use the default compression level in zstd.
163 .El
164 .Pp
165 .It Fl -compress-sections Ns = Ns Ar section-glob={none,zlib,zstd}[:level]
166 Compress output sections that match the glob and do not have the SHF_ALLOC flag.
167 The matched sections remain uncompressed if compressed content would be larger.
168 The compression level is
169 .Cm level
170 (if specified) or a default speed-focused level.
171 This is like a generalized
172 .Cm --compress-debug-sections.
173 .It Fl -cref
174 Output cross reference table. If
175 .Fl Map
176 is specified, print to the map file.
177 .It Fl -debug-names
178 Generate a merged
179 .Li .debug_names
180 section.
181 .It Fl -default-script Ns = Ns Ar file , Fl dT Ar file
182 In the absence of
183 .Fl -script ,
184 read this default linker script.
185 .It Fl -defsym Ns = Ns Ar symbol Ns = Ns Ar expression
186 Define a symbol alias.
187 .Ar expression
188 may be another symbol or a linker script expression.
189 For example,
190 .Ql --defsym=foo=bar
191 or
192 .Ql --defsym=foo=bar+0x100 .
193 .It Fl -demangle
194 Demangle symbol names.
195 .It Fl -disable-new-dtags
196 Disable new dynamic tags.
197 .It Fl -discard-all , Fl x
198 Delete all local symbols.
199 .It Fl -discard-locals , Fl X
200 Delete temporary local symbols.
201 .It Fl -discard-none
202 Keep all symbols in the symbol table.
203 .It Fl -dynamic-linker Ns = Ns Ar value
204 Specify the dynamic linker to be used for a dynamically linked executable.
205 This is recorded in an ELF segment of type
206 .Dv PT_INTERP .
207 .It Fl -dynamic-list Ns = Ns Ar file
208 Similar to
209 .Cm --export-dynamic-symbol-list .
210 When creating a shared object, implies
211 .Cm -Bsymbolic
212 but does not set DF_SYMBOLIC
213 .It Fl -EB
214 Select the big-endian format in the OUTPUT_FORMAT command.
215 .It Fl -EL
216 Select the little-endian format in the OUTPUT_FORMAT command.
217 .It Fl -eh-frame-hdr
218 Request creation of
219 .Li .eh_frame_hdr
220 section and
221 .Dv PT_GNU_EH_FRAME
222 segment header.
223 .It Fl -emit-relocs , Fl q
224 Generate relocations in the output.
225 .It Fl -enable-new-dtags
226 Enable new dynamic tags.
227 .It Fl -enable-non-contiguous-regions
228 Spill input sections to later matching output sections to avoid memory region overflow.
229 .It Fl -end-lib
230 End a grouping of objects that should be treated as if they were together
231 in an archive.
232 .It Fl -entry Ns = Ns Ar entry
233 Name of entry point symbol.
234 .It Fl -error-limit Ns = Ns Ar value
235 Maximum number of errors to emit before stopping.
236 A value of zero indicates that there is no limit.
237 .It Fl -error-unresolved-symbols
238 Report unresolved symbols as errors.
239 .It Fl -error-handing-script Ns = Ns Ar script_path
240 Call script
241 .Ar script_path
242 upon some error, with
243 .Ar tag
244 as first argument, and an extra parameter as second argument. The script is
245 expected to return 0 on success. Any other value is considered a generic error.
246 .Ar tag
247 may be
248 .Cm missing-lib
249 followed by the name of the missing library.
250 .Cm undefined-symbol
251 followed by the name of the undefined symbol.
252 .It Fl -execute-only
253 Mark executable sections unreadable.
254 This option is currently only supported on AArch64.
255 .It Fl -exclude-libs Ns = Ns Ar value
256 Exclude static libraries from automatic export.
257 .It Fl -export-dynamic , Fl E
258 Put symbols in the dynamic symbol table.
259 .It Fl -export-dynamic-symbol Ns = Ns Ar glob
260 (executable) Put matched non-local defined symbols to the dynamic symbol table.
261 (shared object) References to matched non-local STV_DEFAULT symbols shouldn't be bound to definitions within the shared object even if they would otherwise be due to
262 .Cm -Bsymbolic
263 ,
264 .Cm -Bsymbolic-functions
265 or
266 .Cm --dynamic-list
267 .It Fl -export-dynamic-symbol-list Ns = Ns Ar file
268 Read a list of dynamic symbol patterns from
269 .Ar file .
270 Apply
271 .Cm --export-dynamic-symbol
272 on each pattern.
273 .It Fl -fatal-warnings
274 Treat warnings as errors.
275 .It Fl -filter Ns = Ns Ar value , Fl F Ar value
276 Set the
277 .Dv DT_FILTER
278 field to the specified value.
279 .It Fl -fini Ns = Ns Ar symbol
280 Specify a finalizer function.
281 .It Fl -force-group-allocation
282 Only meaningful for -r. Section groups are discarded. If two section group members are placed to the same output section, combine their relocations as well.
283 .It Fl -format Ns = Ns Ar input-format , Fl b Ar input-format
284 Specify the format of the inputs following this option.
285 .Ar input-format
286 may be one of
287 .Cm binary ,
288 .Cm elf ,
289 and
290 .Cm default .
291 .Cm default
292 is a synonym for
293 .Cm elf .
294 .It Fl -gc-sections
295 Enable garbage collection of unused sections.
296 .It Fl -gdb-index
297 Generate
298 .Li .gdb_index
299 section.
300 .It Fl -hash-style Ns = Ns Ar value
301 Specify hash style.
302 .Ar value
303 may be
304 .Cm sysv ,
305 .Cm gnu ,
306 or
307 .Cm both .
308 .Cm both
309 is the default.
310 .It Fl -help
311 Print a help message.
312 .It Fl -icf Ns = Ns Cm all
313 Enable identical code folding.
314 .It Fl -icf Ns = Ns Cm safe
315 Enable safe identical code folding.
316 .It Fl -icf Ns = Ns Cm none
317 Disable identical code folding.
318 .It Fl -ignore-data-address-equality
319 Ignore address equality of data. C/C++ requires each data to have a unique
320 address.
321 This option allows lld to do unsafe optimization that breaks the
322 requirement: create copies of read-only data or merge two or more read-only data
323 that happen to have the same value.
324 .It Fl -ignore-function-address-equality
325 Ignore address equality of functions.
326 This option allows non-PIC calls to a function with non-default visibility in
327 a shared object.
328 The function may have different addresses within the executable and within the
329 shared object.
330 .It Fl -image-base Ns = Ns Ar value
331 Set the base address to
332 .Ar value .
333 .It Fl -init Ns = Ns Ar symbol
334 Specify an initializer function.
335 .It Fl -keep-unique Ns = Ns Ar symbol
336 Do not fold
337 .Ar symbol
338 during ICF.
339 .It Fl l Ar libName, Fl -library Ns = Ns Ar libName
340 Root name of library to use.
341 .It Fl L Ar dir , Fl -library-path Ns = Ns Ar dir
342 Add a directory to the library search path.
343 .It Fl -lto-aa-pipeline Ns = Ns Ar value
344 AA pipeline to run during LTO.
345 Used in conjunction with
346 .Fl -lto-newpm-passes .
347 .It Fl -lto-newpm-passes Ns = Ns Ar value
348 Passes to run during LTO.
349 .It Fl -lto-O Ns Ar opt-level
350 Optimization level for LTO.
351 .It Fl -lto-partitions Ns = Ns Ar value
352 Number of LTO codegen partitions.
353 .It Fl m Ar value
354 Set target emulation.
355 .It Fl -Map Ns = Ns Ar file , Fl M Ar file
356 Print a link map to
357 .Ar file .
358 .It Fl -nmagic , Fl n
359 Do not page align sections, link against static libraries.
360 .It Fl -no-allow-shlib-undefined
361 Do not allow unresolved references in shared libraries.
362 This option is enabled by default when linking an executable.
363 .It Fl -no-as-needed
364 Always set
365 .Dv DT_NEEDED
366 for shared libraries.
367 .It Fl -no-color-diagnostics
368 Do not use colors in diagnostics.
369 .It Fl -no-demangle
370 Do not demangle symbol names.
371 .It Fl -no-dynamic-linker
372 Inhibit output of an
373 .Li .interp
374 section.
375 .It Fl -no-fortran-common
376 Do not search archive members for definitions to override COMMON symbols.
377 .It Fl -no-gc-sections
378 Disable garbage collection of unused sections.
379 .It Fl -no-gnu-unique
380 Disable STB_GNU_UNIQUE symbol binding.
381 .It Fl -no-merge-exidx-entries
382 Disable merging .ARM.exidx entries.
383 .It Fl -no-nmagic
384 Page align sections.
385 .It Fl -no-omagic
386 Do not set the text data sections to be writable, page align sections.
387 .It Fl -no-relax
388 Disable target-specific relaxations. For x86-64 this disables R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX GOT optimization.
389 .It Fl -no-rosegment
390 Do not put read-only non-executable sections in their own segment.
391 .It Fl -undefined-version
392 Do not report version scripts that refer to undefined symbols.
393 .It Fl -no-undefined
394 Report unresolved symbols even if the linker is creating a shared library.
395 .It Fl -no-warn-mismatch
396 Do not reject unknown section types.
397 .It Fl -no-warn-symbol-ordering
398 Do not warn about problems with the symbol ordering file or call graph profile.
399 .It Fl -no-warnings , Fl w
400 Suppress warnings and cancel
401 .Cm --fatal-warnings.
402 .It Fl -no-whole-archive
403 Restores the default behavior of loading archive members.
404 .It Fl -no-pie , Fl -no-pic-executable
405 Do not create a position independent executable.
406 .It Fl -noinhibit-exec
407 Retain the executable output file whenever it is still usable.
408 .It Fl -nostdlib
409 Only search directories specified on the command line.
410 .It Fl o Ar path
411 Write the output executable, library, or object to
412 .Ar path .
413 If not specified,
414 .Dv a.out
415 is used as a default.
416 .It Fl O Ns Ar value
417 Optimize output file size.
418 .Ar value
419 may be:
420 .Pp
421 .Bl -tag -width 2n -compact
422 .It Cm 0
423 Disable string merging.
424 .It Cm 1
425 Enable string merging.
426 .It Cm 2
427 Enable string tail merging.
428 .El
429 .Pp
430 .Fl O Ns Cm 1
431 is the default.
432 .It Fl -oformat Ns = Ns Ar format
433 Specify the format for the output object file.
434 The only supported
435 .Ar format
436 is
437 .Cm binary ,
438 which produces output with no ELF header.
439 .It Fl -omagic , Fl N
440 Set the text and data sections to be readable and writable, do not page align
441 sections, link against static libraries.
442 .It Fl -opt-remarks-filename Ar file
443 Write optimization remarks in YAML format to
444 .Ar file .
445 .It Fl -opt-remarks-passes Ar pass-regex
446 Filter optimization remarks by only allowing the passes matching
447 .Ar pass-regex .
448 .It Fl -opt-remarks-with-hotness
449 Include hotness information in the optimization remarks file.
450 .It Fl -orphan-handling Ns = Ns Ar mode
451 Control how orphan sections are handled.
452 An orphan section is one not specifically mentioned in a linker script.
453 .Ar mode
454 may be:
455 .Pp
456 .Bl -tag -width 2n -compact
457 .It Cm place
458 Place orphan sections in suitable output sections.
459 .It Cm warn
460 Place orphan sections as for
461 .Cm place
462 and also report a warning.
463 .It Cm error
464 Place orphan sections as for
465 .Cm place
466 and also report an error.
467 .El
468 .Pp
469 .Cm place
470 is the default.
471 .It Fl -pack-dyn-relocs Ns = Ns Ar format
472 Pack dynamic relocations in the given format.
473 .Ar format
474 may be:
475 .Pp
476 .Bl -tag -width 2n -compact
477 .It Cm none
478 Do not pack.
479 Dynamic relocations are encoded in SHT_REL(A).
480 .It Cm android
481 Pack dynamic relocations in SHT_ANDROID_REL(A).
482 .It Cm relr
483 Pack relative relocations in SHT_RELR, and the rest of dynamic relocations in
484 SHT_REL(A).
485 .It Cm android+relr
486 Pack relative relocations in SHT_RELR, and the rest of dynamic relocations in
487 SHT_ANDROID_REL(A).
488 .El
489 .Pp
490 .Cm none
491 is the default.
492 If
493 .Fl -use-android-relr-tags
494 is specified, use SHT_ANDROID_RELR instead of SHT_RELR.
495 .Pp
496 .It Fl -pic-veneer
497 Always generate position independent thunks.
498 .It Fl -pie , Fl -pic-executable
499 Create a position independent executable.
500 .It Fl -power10-stubs Ns = Ns Cm mode
501 Whether to use Power10 instructions in call stubs for R_PPC64_REL24_NOTOC and TOC/NOTOC interworking.
502 .Ar mode
503 may be:
504 .Pp
505 .Bl -tag -width 2n -compact
506 .It Cm yes
507 (default) Use.
508 .It Cm auto
509 Currently the same as yes.
510 .It Cm no
511 Don't use.
512 .El
514 .It Fl -print-gc-sections
515 List removed unused sections.
516 .It Fl -print-icf-sections
517 List identical folded sections.
518 .It Fl -print-map
519 Print a link map to the standard output.
520 .It Fl -print-archive-stats Ns = Ns Ar file
521 Write archive usage statistics to the specified file.
522 Print the numbers of members and fetched members for each archive.
523 .It Fl -push-state
524 Save the current state of
525 .Fl -as-needed ,
526 .Fl -static ,
527 and
528 .Fl -whole-archive.
529 .It Fl -pop-state
530 Restore the states saved by
531 .Fl -push-state.
532 .It Fl --relax-gp
533 Enable global pointer relaxation for RISC-V.
534 .It Fl -relocatable , Fl r
535 Create relocatable object file.
536 .It Fl -remap-inputs Ns = Ns Ar from-glob=to-file
537 Input files matching
538 .Cm from-glob
539 are mapped to
540 .Cm to-file.
541 Use
542 .Cm /dev/null
543 to ignore an input file.
544 .It Fl -remap-inputs-file Ns = Ns Ar file
545 Remap input files based on patterns in
546 .Ar file .
547 Each line in the remap file is of the format
548 .Cm from-glob=to-file
549 or a comment starting with
550 .Cm # .
551 .It Fl -reproduce Ns = Ns Ar path
552 Write a tar file to
553 .Ar path,
554 containing all the input files needed to reproduce the link, a text file called
555 response.txt containing the command line options and a text file called
556 version.txt containing the output of ld.lld --version.
557 The archive when
558 unpacked can be used to re-run the linker with the same options and input files.
559 .It Fl -retain-symbols-file Ns = Ns Ar file
560 Retain only the symbols listed in the file.
561 .It Fl -rpath Ns = Ns Ar value , Fl R Ar value
562 Add a
563 .Dv DT_RUNPATH
564 to the output.
565 .It Fl -rsp-quoting Ns = Ns Ar value
566 Quoting style for response files.
567 The supported values are
568 .Cm windows
569 and
570 .Cm posix .
571 .It Fl -script Ns = Ns Ar file , Fl T Ar file
572 Read linker script from
573 .Ar file .
574 If multiple linker scripts are given, they are processed as if they
575 were concatenated in the order they appeared on the command line.
576 .It Fl -section-start Ns = Ns Ar section Ns = Ns Ar address
577 Set address of section.
578 .It Fl -shared , Fl -Bsharable
579 Build a shared object.
580 .It Fl -shuffle-sections Ns = Ns Ar seed
581 Shuffle matched sections using the given seed before mapping them to the output sections.
582 If -1, reverse the section order. If 0, use a random seed.
583 .It Fl -soname Ns = Ns Ar value , Fl h Ar value
584 Set
585 .Dv DT_SONAME
586 to
587 .Ar value .
588 .It Fl -sort-common
589 This option is ignored for GNU compatibility.
590 .It Fl -sort-section Ns = Ns Ar value
591 Specifies sections sorting rule when linkerscript is used.
592 .It Fl -start-lib
593 Start a grouping of objects that should be treated as if they were together
594 in an archive.
595 .It Fl -strip-all , Fl s
596 Strip all symbols.
597 Implies
598 .Fl -strip-debug .
599 .It Fl -strip-debug , Fl S
600 Strip debugging information.
601 .It Fl -symbol-ordering-file Ns = Ns Ar file
602 Lay out sections in the order specified by
603 .Ar file .
604 .It Fl -sysroot Ns = Ns Ar value
605 Set the system root.
606 .It Fl -target1-abs
607 Interpret
608 .Dv R_ARM_TARGET1
609 as
610 .Dv R_ARM_ABS32 .
611 .It Fl -target1-rel
612 Interpret
613 .Dv R_ARM_TARGET1
614 as
615 .Dv R_ARM_REL32 .
616 .It Fl -target2 Ns = Ns Ar type
617 Interpret
618 .Dv R_ARM_TARGET2
619 as
620 .Ar type ,
621 where
622 .Ar type
623 is one of
624 .Cm rel ,
625 .Cm abs ,
626 or
627 .Cm got-rel .
628 .It Fl -Tbss Ns = Ns Ar value
629 Same as
630 .Fl -section-start
631 with
632 .Li .bss
633 as the sectionname.
634 .It Fl -Tdata Ns = Ns Ar value
635 Same as
636 .Fl -section-start
637 with
638 .Li .data
639 as the sectionname.
640 .It Fl -Ttext Ns = Ns Ar value
641 Same as
642 .Fl -section-start
643 with
644 .Li .text
645 as the sectionname.
646 .It Fl -thinlto-cache-dir Ns = Ns Ar value
647 Path to ThinLTO cached object file directory.
648 .It Fl -thinlto-cache-policy Ns = Ns Ar value
649 Pruning policy for the ThinLTO cache.
650 .It Fl -thinlto-jobs Ns = Ns Ar value
651 Number of ThinLTO jobs.
652 .It Fl -threads Ns = Ns Ar N
653 Number of threads.
654 .Cm all
655 (default) means all of concurrent threads supported.
656 .Cm 1
657 disables multi-threading.
658 .It Fl -fat-lto-objects
659 Use the .llvm.lto section, which contains LLVM bitcode, in fat LTO object files to perform LTO.
660 .It Fl -no-fat-lto-objects
661 Ignore the .llvm.lto section in relocatable object files (default).
662 .It Fl -time-trace
663 Record time trace.
664 .It Fl -time-trace-file Ns = Ns Ar file
665 Write time trace output to
666 .Ar file .
667 .It Fl -time-trace-granularity Ns = Ns Ar value
668 Minimum time granularity (in microseconds) traced by time profiler.
669 .It Fl -trace
670 Print the names of the input files.
671 .It Fl -trace-symbol Ns = Ns Ar symbol , Fl y Ar symbol
672 Trace references to
673 .Ar symbol .
674 .It Fl -undefined Ns = Ns Ar symbol , Fl u Ar symbol
675 If
676 .Ar symbol
677 is not defined after symbol resolution, and there's a static library
678 that contains an object file defining the symbol, load the member
679 to include the object file in the output file.
680 .It Fl -undefined-glob Ns = Ns Ar pattern
681 Synonym for
682 .Fl -undefined ,
683 except that it takes a glob pattern.
684 In a glob pattern,
685 .Cm *
686 matches zero or more characters,
687 .Cm ?
688 matches any single character, and
689 .Cm [...]
690 matches the characters within brackets.
691 All symbols that match
692 a given pattern are handled as if they were given as arguments of
693 .Fl -undefined .
694 .It Fl -unique
695 Creates a separate output section for every orphan input section.
696 .It Fl -unresolved-symbols Ns = Ns Ar value
697 Determine how to handle unresolved symbols.
698 .It Fl -use-android-relr-tags
699 Use SHT_ANDROID_RELR / DT_ANDROID_RELR* tags instead of SHT_RELR / DT_RELR*.
700 .It Fl v , Fl V
701 Display the version number and proceed with linking if object files are
702 specified.
703 .It Fl -version
704 Display the version number and exit.
705 .It Fl -verbose
706 Verbose mode.
707 .It Fl -version-script Ns = Ns Ar file
708 Read version script from
709 .Ar file .
710 .It Fl -warn-backrefs
711 Warn about reverse or cyclic dependencies to or between static archives.
712 This can be used to ensure linker invocation remains compatible with
713 traditional Unix-like linkers.
714 .It Fl -warn-backrefs-exclude Ns = Ns Ar glob
715 Glob describing an archive (or an object file within --start-lib)
716 which should be ignored for
717 .Fl -warn-backrefs
718 .It Fl -warn-common
719 Warn about duplicate common symbols.
720 .It Fl -warn-ifunc-textrel
721 Warn about using ifunc symbols in conjunction with text relocations.
722 Older versions of glibc library (2.28 and earlier) has a bug that causes
723 the segment that includes ifunc symbols to be marked as not executable when
724 they are relocated.
725 As a result, although the program compiles and links
726 successfully, it gives segmentation fault when the instruction pointer reaches
727 an ifunc symbol.
728 Use -warn-ifunc-textrel to let lld give a warning, if the
729 code may include ifunc symbols, may do text relocations and be linked with
730 an older glibc version.
731 Otherwise, there is no need to use it, as the default value does not give a
732 warning.
733 This flag has been introduced in late 2018, has no counter part in ld and gold
734 linkers, and may be removed in the future.
735 .It Fl -warn-unresolved-symbols
736 Report unresolved symbols as warnings.
737 .It Fl -whole-archive
738 Force load of all members in a static library.
739 .It Fl -why-extract Ns = Ns Ar file
740 Print to a file about why archive members are extracted.
741 .It Fl -wrap Ns = Ns Ar symbol
742 Redirect
743 .Ar symbol
744 references to
745 .Ar __wrap_symbol
746 and
747 .Ar __real_symbol
748 references to
749 .Ar symbol.
750 .It Fl z Ar option
751 Linker option extensions.
752 .Bl -tag -width indent -compact
753 .Pp
754 .It Cm dead-reloc-in-nonalloc Ns = Ns Ar section_glob=value
755 Resolve a relocation in a matched non-SHF_ALLOC section referencing a discarded symbol to
756 .Ar value
757 Accepts globs, in the event of a section matching more than one option, the last
758 option takes precedence. An order of least specific to most specific match is
759 recommended.
760 .Pp
761 .It Cm execstack
762 Make the main stack executable.
763 Stack permissions are recorded in the
764 .Dv PT_GNU_STACK
765 segment.
766 .Pp
767 .It Cm bti-report Ns = Ns Ar [none|warning|error]
768 Specify how to report the missing GNU_PROPERTY_AARCH64_FEATURE_1_BTI property.
769 .Cm none
770 is the default, linker will not report the missing property otherwise will be reported as a warning or an error.
771 .Pp
772 .It Cm cet-report Ns = Ns Ar [none|warning|error]
773 Specify how to report the missing GNU_PROPERTY_X86_FEATURE_1_IBT or GNU_PROPERTY_X86_FEATURE_1_SHSTK properties.
774 .Cm none
775 is the default, linker will not report the missing property otherwise will be reported as a warning or an error.
776 .Pp
777 .It Cm pauth-report Ns = Ns Ar [none|warning|error]
778 Specify how to report the missing GNU_PROPERTY_AARCH64_FEATURE_PAUTH property.
779 .Cm none
780 is the default, linker will not report the missing property otherwise will be reported as a warning or an error.
781 .Pp
782 .It Cm force-bti
783 Force enable AArch64 BTI instruction in PLT, warn if Input ELF file does not have GNU_PROPERTY_AARCH64_FEATURE_1_BTI property.
784 .Pp
785 .It Cm force-ibt
786 Force enable Intel Indirect Branch Tracking in PLT, warn if an input ELF file
787 does not have GNU_PROPERTY_X86_FEATURE_1_IBT property.
788 .Pp
789 .It Cm global
790 Sets the
791 .Dv DF_1_GLOBAL flag in the
792 .Dv DYNAMIC
793 section.
794 Different loaders can decide how to handle this flag on their own.
795 .Pp
796 .It Cm ifunc-noplt
797 Do not emit PLT entries for ifunc symbols.
798 Instead, emit text relocations referencing the resolver.
799 This is an experimental optimization and only suitable for standalone
800 environments where text relocations do not have the usual drawbacks.
801 This option must be combined with the
802 .Fl z Li notext
803 option.
804 .Pp
805 .It Cm initfirst
806 Sets the
807 .Dv DF_1_INITFIRST
808 flag to indicate the module should be initialized first.
809 .Pp
810 .It Cm interpose
811 Set the
812 .Dv DF_1_INTERPOSE
813 flag to indicate to the runtime linker that the object is an interposer.
814 During symbol resolution interposers are searched after the application
815 but before other dependencies.
816 .Pp
817 .It Cm lrodata-after-bss
818 Place .lrodata after .bss.
819 .Pp
820 .It Cm muldefs
821 Do not error if a symbol is defined multiple times.
822 The first definition will be used.
823 This is a synonym for
824 .Fl -allow-multiple-definition.
825 .Pp
826 .It Cm nocombreloc
827 Disable combining and sorting multiple relocation sections.
828 .Pp
829 .It Cm nocopyreloc
830 Disable the creation of copy relocations.
831 .Pp
832 .It Cm nodefaultlib
833 Set the
834 .Dv DF_1_NODEFLIB
835 flag to indicate that default library search paths should be ignored.
836 .Pp
837 .It Cm nodelete
838 Set the
839 .Dv DF_1_NODELETE
840 flag to indicate that the object cannot be unloaded from a process.
841 .Pp
842 .It Cm nodlopen
843 Set the
844 .Dv DF_1_NOOPEN
845 flag to indicate that the object may not be opened by
846 .Xr dlopen 3 .
847 .Pp
848 .It Cm nognustack
849 Do not emit the
850 .Dv PT_GNU_STACK
851 segment.
852 .Pp
853 .It Cm norelro
854 Do not indicate that portions of the object should be mapped read-only
855 after initial relocation processing.
856 The object will omit the
857 .Dv PT_GNU_RELRO
858 segment.
859 .Pp
860 .It Cm nosectionheader
861 Don't generate the section header table.
862 .Pp
863 .It Cm notext
864 Allow relocations against read-only segments.
865 Sets the
866 .Dv DT_TEXTREL flag in the
867 .Dv DYNAMIC
868 section.
869 .Pp
870 .It Cm now
871 Set the
872 .Dv DF_BIND_NOW
873 flag to indicate that the run-time loader should perform all relocation
874 processing as part of object initialization.
875 By default relocations may be performed on demand.
876 .Pp
877 .It Cm origin
878 Set the
879 .Dv DF_ORIGIN
880 flag to indicate that the object requires
881 $ORIGIN
882 processing.
883 .Pp
884 .It Cm pac-plt
885 AArch64 only, use pointer authentication in PLT.
886 .Pp
887 .It Cm pack-relative-relocs
888 Similar to
889 .Cm -pack-dyn-relocs=relr
890 , but synthesizes the GLIBC_ABI_DT_RELR version dependency if there is a GLIBC_2.* version dependency.
891 glibc ld.so rejects loading a dynamically linked object without the GLIBC_ABI_DT_RELR version dependency.
892 .Pp
893 .It Cm rel
894 Use REL format for dynamic relocations.
895 .Pp
896 .It Cm rela
897 Use RELA format for dynamic relocations.
898 .Pp
899 .It Cm retpolineplt
900 Emit retpoline format PLT entries as a mitigation for CVE-2017-5715.
901 .Pp
902 .It Cm rodynamic
903 Make the
904 .Li .dynamic
905 section read-only.
906 The
907 .Dv DT_DEBUG
908 tag will not be emitted.
909 .Pp
910 .It Cm separate-loadable-segments
911 .It Cm separate-code
912 .It Cm noseparate-code
913 Specify whether two adjacent PT_LOAD segments are allowed to overlap in pages.
914 .Cm noseparate-code
915 (default) allows overlap.
916 .Cm separate-code
917 allows overlap between two executable segments, or two non-executable segments.
918 .Cm separate-loadable-segments
919 disallows overlap.
920 .Pp
921 .It Cm shstk
922 x86 only, use shadow stack.
923 .Pp
924 .It Cm stack-size Ns = Ns Ar size
925 Set the main thread's stack size to
926 .Ar size .
927 The stack size is recorded as the size of the
928 .Ar size .
929 .Dv PT_GNU_STACK
930 program segment.
931 .Pp
932 .It Cm start-stop-gc
933 Don't let __start_/__stop_ references retain the associated C identifier name sections (default).
934 .Pp
935 .It Cm nostart-stop-gc
936 Let __start_/__stop_ references retain the associated C identifier name sections.
937 .Pp
938 .It Cm text
939 Do not allow relocations against read-only segments.
940 This is the default.
941 .Pp
942 .It Cm wxneeded
943 Create a
944 .Dv PT_OPENBSD_WXNEEDED
945 segment.
946 .El
947 .El
949 .Sh ENVIRONMENT VARIABLES
950 .Bl -tag -width LC_CTYPE
951 .It Ev LLD_REPRODUCE
952 Create a reproduce tarball with the specified filename. If
953 .Fl -reproduce
954 is specified,
955 .Fl -reproduce
956 takes precedence.
957 .It Ev LLD_VERSION
958 ld.lld creates a section named
959 .Cm .comment
960 containing the LLD version string. The version string can be overridden by this environment variable,
961 which is useful to eliminate differences in the binary caused by LLD version number differences.
962 .El
964 .Sh IMPLEMENTATION NOTES
965 .Nm Ap s
966 handing of archive files (those with a
967 .Pa .a
968 file extension) is different from traditional linkers used on Unix-like
969 systems.
970 .Pp
971 Traditional linkers maintain a set of undefined symbols during linking.
972 The linker processes each file in the order in which it appears on the
973 command line, until the set of undefined symbols becomes empty.
974 An object file is linked into the output object when it is encountered,
975 with its undefined symbols added to the set.
976 Upon encountering an archive file a traditional linker searches the objects
977 contained therein, and processes those that satisfy symbols in the unresolved
978 set.
979 .Pp
980 Handling mutually dependent archives may be awkward when using a traditional
981 linker.
982 Archive files may have to be specified multiple times, or the special command
983 line options
984 .Fl -start-group
985 and
986 .Fl -end-group
987 may be used to have the linker loop over the files in the group until no new
988 symbols are added to the set.
989 .Pp
990 .Nm
991 records all symbols found in objects and archives as it iterates over
992 command line arguments.
993 When
994 .Nm
995 encounters an undefined symbol that can be resolved by an object file
996 contained in a previously processed archive file, it immediately extracts
997 and links it into the output object.
998 .Pp
999 With certain archive inputs
1000 .Nm
1001 may produce different results compared to traditional linkers.
1002 In practice, large bodies of third party software have been linked with
1003 .Nm
1004 without material issues.
1005 .Pp
1006 The
1007 .Fl -warn-backrefs
1008 option may be used to identify a linker invocation that may be incompatible
1009 with traditional Unix-like linker behavior.