ld

对gcc编译器比较熟悉的朋友肯定对ld有了解。这是一个链接器，linux下通过gcc编译c程序的话，链接就是通过ld来完成的。

写道

# ld --help
Usage: ld [options] file...
Options:
-a KEYWORD Shared library control for HP/UX compatibility
-A ARCH, --architecture ARCH
Set architecture
-b TARGET, --format TARGET Specify target for following input files
-c FILE, --mri-script FILE Read MRI format linker script
-d, -dc, -dp Force common symbols to be defined
-e ADDRESS, --entry ADDRESS Set start address
-E, --export-dynamic Export all dynamic symbols
--no-export-dynamic Undo the effect of --export-dynamic
-EB Link big-endian objects
-EL Link little-endian objects
-f SHLIB, --auxiliary SHLIB Auxiliary filter for shared object symbol table
-F SHLIB, --filter SHLIB Filter for shared object symbol table
-g Ignored
-G SIZE, --gpsize SIZE Small data size (if no size, same as --shared)
-h FILENAME, -soname FILENAME
Set internal name of shared library
-I PROGRAM, --dynamic-linker PROGRAM
Set PROGRAM as the dynamic linker to use
-l LIBNAME, --library LIBNAME
Search for library LIBNAME
-L DIRECTORY, --library-path DIRECTORY
Add DIRECTORY to library search path
--sysroot=<DIRECTORY> Override the default sysroot location
-m EMULATION Set emulation
-M, --print-map Print map file on standard output
-n, --nmagic Do not page align data
-N, --omagic Do not page align data, do not make text readonly
--no-omagic Page align data, make text readonly
-o FILE, --output FILE Set output file name
-O Optimize output file
-Qy Ignored for SVR4 compatibility
-q, --emit-relocs Generate relocations in final output
-r, -i, --relocatable Generate relocatable output
-R FILE, --just-symbols FILE
Just link symbols (if directory, same as --rpath)
-s, --strip-all Strip all symbols
-S, --strip-debug Strip debugging symbols
--strip-discarded Strip symbols in discarded sections
--no-strip-discarded Do not strip symbols in discarded sections
-t, --trace Trace file opens
-T FILE, --script FILE Read linker script
--default-script FILE, -dT Read default linker script
-u SYMBOL, --undefined SYMBOL
Start with undefined reference to SYMBOL
--unique [=SECTION] Don't merge input [SECTION | orphan] sections
-Ur Build global constructor/destructor tables
-v, --version Print version information
-V Print version and emulation information
-x, --discard-all Discard all local symbols
-X, --discard-locals Discard temporary local symbols (default)
--discard-none Don't discard any local symbols
-y SYMBOL, --trace-symbol SYMBOL
Trace mentions of SYMBOL
-Y PATH Default search path for Solaris compatibility
-(, --start-group Start a group
-), --end-group End a group
--accept-unknown-input-arch Accept input files whose architecture cannot be determined
--no-accept-unknown-input-arch
Reject input files whose architecture is unknown
--as-needed Only set DT_NEEDED for following dynamic libs if used
--no-as-needed Always set DT_NEEDED for dynamic libraries mentioned on
the command line
-assert KEYWORD Ignored for SunOS compatibility
-Bdynamic, -dy, -call_shared
Link against shared libraries
-Bstatic, -dn, -non_shared, -static
Do not link against shared libraries
-Bsymbolic Bind global references locally
-Bsymbolic-functions Bind global function references locally
--check-sections Check section addresses for overlaps (default)
--no-check-sections Do not check section addresses for overlaps
--copy-dt-needed-entries Copy DT_NEEDED links mentioned inside DSOs that follow
--no-copy-dt-needed-entries Do not copy DT_NEEDED links mentioned inside DSOs that follow
--cref Output cross reference table
--defsym SYMBOL=EXPRESSION Define a symbol
--demangle [=STYLE] Demangle symbol names [using STYLE]
--embedded-relocs Generate embedded relocs
--fatal-warnings Treat warnings as errors
--no-fatal-warnings Do not treat warnings as errors (default)
-fini SYMBOL Call SYMBOL at unload-time
--force-exe-suffix Force generation of file with .exe suffix
--gc-sections Remove unused sections (on some targets)
--no-gc-sections Don't remove unused sections (default)
--print-gc-sections List removed unused sections on stderr
--no-print-gc-sections Do not list removed unused sections
--hash-size=<NUMBER> Set default hash table size close to <NUMBER>
--help Print option help
-init SYMBOL Call SYMBOL at load-time
-Map FILE Write a map file
--no-define-common Do not define Common storage
--no-demangle Do not demangle symbol names
--no-keep-memory Use less memory and more disk I/O
--no-undefined Do not allow unresolved references in object files
--allow-shlib-undefined Allow unresolved references in shared libaries
--no-allow-shlib-undefined Do not allow unresolved references in shared libs
--allow-multiple-definition Allow multiple definitions
--no-undefined-version Disallow undefined version
--default-symver Create default symbol version
--default-imported-symver Create default symbol version for imported symbols
--no-warn-mismatch Don't warn about mismatched input files
--no-warn-search-mismatch Don't warn on finding an incompatible library
--no-whole-archive Turn off --whole-archive
--noinhibit-exec Create an output file even if errors occur
-nostdlib Only use library directories specified on
the command line
--oformat TARGET Specify target of output file
-qmagic Ignored for Linux compatibility
--reduce-memory-overheads Reduce memory overheads, possibly taking much longer
--relax Relax branches on certain targets
--retain-symbols-file FILE Keep only symbols listed in FILE
-rpath PATH Set runtime shared library search path
-rpath-link PATH Set link time shared library search path
-shared, -Bshareable Create a shared library
-pie, --pic-executable Create a position independent executable
--sort-common [=ascending|descending]
Sort common symbols by alignment [in specified order]
--sort-section name|alignment
Sort sections by name or maximum alignment
--spare-dynamic-tags COUNT How many tags to reserve in .dynamic section
--split-by-file [=SIZE] Split output sections every SIZE octets
--split-by-reloc [=COUNT] Split output sections every COUNT relocs
--stats Print memory usage statistics
--target-help Display target specific options
--task-link SYMBOL Do task level linking
--traditional-format Use same format as native linker
--section-start SECTION=ADDRESS
Set address of named section
-Tbss ADDRESS Set address of .bss section
-Tdata ADDRESS Set address of .data section
-Ttext ADDRESS Set address of .text section
-Ttext-segment ADDRESS Set address of text segment
--unresolved-symbols=<method>
How to handle unresolved symbols. <method> is:
ignore-all, report-all, ignore-in-object-files,
ignore-in-shared-libs
--verbose Output lots of information during link
--version-script FILE Read version information script
--version-exports-section SYMBOL
Take export symbols list from .exports, using
SYMBOL as the version.
--dynamic-list-data Add data symbols to dynamic list
--dynamic-list-cpp-new Use C++ operator new/delete dynamic list
--dynamic-list-cpp-typeinfo Use C++ typeinfo dynamic list
--dynamic-list FILE Read dynamic list
--warn-common Warn about duplicate common symbols
--warn-constructors Warn if global constructors/destructors are seen
--warn-multiple-gp Warn if the multiple GP values are used
--warn-once Warn only once per undefined symbol
--warn-section-align Warn if start of section changes due to alignment
--warn-shared-textrel Warn if shared object has DT_TEXTREL
--warn-alternate-em Warn if an object has alternate ELF machine code
--warn-unresolved-symbols Report unresolved symbols as warnings
--error-unresolved-symbols Report unresolved symbols as errors
--whole-archive Include all objects from following archives
--wrap SYMBOL Use wrapper functions for SYMBOL
@FILE Read options from FILE
ld: supported targets: elf32-i386 a.out-i386-linux pei-i386 elf64-x86-64 elf64-l1om elf64-little elf64-big elf32-little elf32-big srec symbolsrec verilog tekhex binary ihex trad-core
ld: supported emulations: elf_i386 i386linux elf_x86_64 elf_l1om
ld: emulation specific options:
elf_i386:
--build-id[=STYLE] Generate build ID note
--audit=AUDITLIB Specify a library to use for auditing
-P AUDITLIB, --depaudit=AUDITLIB
Specify a library to use for auditing dependencies
-Bgroup Selects group name lookup rules for DSO
--disable-new-dtags Disable new dynamic tags
--enable-new-dtags Enable new dynamic tags
--eh-frame-hdr Create .eh_frame_hdr section
--hash-style=STYLE Set hash style to sysv, gnu or both
-z combreloc Merge dynamic relocs into one section and sort
-z defs Report unresolved symbols in object files.
-z execstack Mark executable as requiring executable stack
-z initfirst Mark DSO to be initialized first at runtime
-z interpose Mark object to interpose all DSOs but executable
-z lazy Mark object lazy runtime binding (default)
-z loadfltr Mark object requiring immediate process
-z muldefs Allow multiple definitions
-z nocombreloc Don't merge dynamic relocs into one section
-z nocopyreloc Don't create copy relocs
-z nodefaultlib Mark object not to use default search paths
-z nodelete Mark DSO non-deletable at runtime
-z nodlopen Mark DSO not available to dlopen
-z nodump Mark DSO not available to dldump
-z noexecstack Mark executable as not requiring executable stack
-z norelro Don't create RELRO program header
-z now Mark object non-lazy runtime binding
-z origin Mark object requiring immediate $ORIGIN
processing at runtime
-z relro Create RELRO program header
-z max-page-size=SIZE Set maximum page size to SIZE
-z common-page-size=SIZE Set common page size to SIZE
-z KEYWORD Ignored for Solaris compatibility
elf_x86_64:
--build-id[=STYLE] Generate build ID note
--audit=AUDITLIB Specify a library to use for auditing
-P AUDITLIB, --depaudit=AUDITLIB
Specify a library to use for auditing dependencies
-Bgroup Selects group name lookup rules for DSO
--disable-new-dtags Disable new dynamic tags
--enable-new-dtags Enable new dynamic tags
--eh-frame-hdr Create .eh_frame_hdr section
--hash-style=STYLE Set hash style to sysv, gnu or both
-z combreloc Merge dynamic relocs into one section and sort
-z defs Report unresolved symbols in object files.
-z execstack Mark executable as requiring executable stack
-z initfirst Mark DSO to be initialized first at runtime
-z interpose Mark object to interpose all DSOs but executable
-z lazy Mark object lazy runtime binding (default)
-z loadfltr Mark object requiring immediate process
-z muldefs Allow multiple definitions
-z nocombreloc Don't merge dynamic relocs into one section
-z nocopyreloc Don't create copy relocs
-z nodefaultlib Mark object not to use default search paths
-z nodelete Mark DSO non-deletable at runtime
-z nodlopen Mark DSO not available to dlopen
-z nodump Mark DSO not available to dldump
-z noexecstack Mark executable as not requiring executable stack
-z norelro Don't create RELRO program header
-z now Mark object non-lazy runtime binding
-z origin Mark object requiring immediate $ORIGIN
processing at runtime
-z relro Create RELRO program header
-z max-page-size=SIZE Set maximum page size to SIZE
-z common-page-size=SIZE Set common page size to SIZE
-z KEYWORD Ignored for Solaris compatibility
elf_l1om:
--build-id[=STYLE] Generate build ID note
--audit=AUDITLIB Specify a library to use for auditing
-P AUDITLIB, --depaudit=AUDITLIB
Specify a library to use for auditing dependencies
-Bgroup Selects group name lookup rules for DSO
--disable-new-dtags Disable new dynamic tags
--enable-new-dtags Enable new dynamic tags
--eh-frame-hdr Create .eh_frame_hdr section
--hash-style=STYLE Set hash style to sysv, gnu or both
-z combreloc Merge dynamic relocs into one section and sort
-z defs Report unresolved symbols in object files.
-z execstack Mark executable as requiring executable stack
-z initfirst Mark DSO to be initialized first at runtime
-z interpose Mark object to interpose all DSOs but executable
-z lazy Mark object lazy runtime binding (default)
-z loadfltr Mark object requiring immediate process
-z muldefs Allow multiple definitions
-z nocombreloc Don't merge dynamic relocs into one section
-z nocopyreloc Don't create copy relocs
-z nodefaultlib Mark object not to use default search paths
-z nodelete Mark DSO non-deletable at runtime
-z nodlopen Mark DSO not available to dlopen
-z nodump Mark DSO not available to dldump
-z noexecstack Mark executable as not requiring executable stack
-z norelro Don't create RELRO program header
-z now Mark object non-lazy runtime binding
-z origin Mark object requiring immediate $ORIGIN
processing at runtime
-z relro Create RELRO program header
-z max-page-size=SIZE Set maximum page size to SIZE
-z common-page-size=SIZE Set common page size to SIZE
-z KEYWORD Ignored for Solaris compatibility

Report bugs to <http://bugzilla.redhat.com/bugzilla/>

 

--oformat TARGET

指定链接输出的文件格式。这里的TARGET指定的是bfdname，表示输出文件是哪种BFD格式。

 

可通过objdump工具查看支持的格式

# objdump -i

BFD header file version version 2.20.51.0.2-5.48.el6 20100205

elf32-i386

 (header little endian, data little endian)

  i386

a.out-i386-linux

 (header little endian, data little endian)

  i386

pei-i386

 (header little endian, data little endian)

  i386

elf64-x86-64

 (header little endian, data little endian)

  i386

elf64-l1om

 (header little endian, data little endian)

  l1om

elf64-little

 (header little endian, data little endian)

  i386

  l1om

elf64-big

 (header big endian, data big endian)

  i386

  l1om

elf32-little

 (header little endian, data little endian)

  i386

  l1om

elf32-big

 (header big endian, data big endian)

  i386

  l1om

srec

 (header endianness unknown, data endianness unknown)

  i386

  l1om

symbolsrec

 (header endianness unknown, data endianness unknown)

  i386

  l1om

verilog

 (header endianness unknown, data endianness unknown)

  i386

  l1om

tekhex

 (header endianness unknown, data endianness unknown)

  i386

  l1om

binary

 (header endianness unknown, data endianness unknown)

  i386

  l1om

ihex

 (header endianness unknown, data endianness unknown)

  i386

  l1om

trad-core

 (header endianness unknown, data endianness unknown)

 

               elf32-i386 a.out-i386-linux pei-i386 elf64-x86-64 elf64-l1om 

          i386 elf32-i386 a.out-i386-linux pei-i386 elf64-x86-64 ---------- 

          l1om ---------- ---------------- -------- ------------ elf64-l1om 

 

               elf64-little elf64-big elf32-little elf32-big srec symbolsrec 

          i386 elf64-little elf64-big elf32-little elf32-big srec symbolsrec 

          l1om elf64-little elf64-big elf32-little elf32-big srec symbolsrec 

 

               verilog tekhex binary ihex trad-core 

          i386 verilog tekhex binary ihex --------- 

          l1om verilog tekhex binary ihex --------- 

在链接脚本文件中指定的OUTPUT_FORMAT和这里命令行上指定--oformat TARGET是一样的意思。

如：

OUTPUT_FORMAT("pe-i386")

如果同时在命令行和链接脚本中都指定了，优先使用命令行的方式。

 

在windows下通过cygwin使用该ld是不支持指定binary的输出格式：

OUTPUT_FORMAT("binary")

或者在命令行中指定--oformat binary

 

ld: cannot perform PE operations on non PE output file 'setup.exe'.

 

如果需要输出binary纯二进制镜像的话，可以通过objcpy生成：

参考另一篇文章：https://www.iteye.com/blog/lobin-2437928