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Annotation of 43BSDReno/pgrm/ld/ld.1, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980, 1990 The Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"     @(#)ld.1       6.4 (Berkeley) 7/24/90
        !             6: .\"
        !             7: .Dd July 24, 1990
        !             8: .Dt LD 1
        !             9: .Os BSD 4
        !            10: .Sh NAME
        !            11: .Nm ld
        !            12: .Nd link editor
        !            13: .Sh SYNOPSIS
        !            14: .Nm ld
        !            15: .Op  option
        !            16: \&...
        !            17: .Ar file ...
        !            18: .Sh DESCRIPTION
        !            19: .Nm Ld
        !            20: combines several
        !            21: object programs into one, resolves external
        !            22: references, and searches libraries.
        !            23: In the simplest case several object
        !            24: .Ar files
        !            25: are given, and
        !            26: .Nm ld
        !            27: combines them, producing
        !            28: an object module which can be either executed or
        !            29: become the input for a further
        !            30: .Nm ld
        !            31: run.
        !            32: (In the latter case, the
        !            33: .Fl r
        !            34: option must be given
        !            35: to preserve the relocation bits.)
        !            36: The output of
        !            37: .Nm ld
        !            38: is left on
        !            39: .Pa a.out  .
        !            40: This file is made executable
        !            41: only if no errors occurred during the load.
        !            42: .Pp
        !            43: The argument routines are concatenated in the order
        !            44: specified.  The entry point of the output is the
        !            45: beginning of the first routine (unless the
        !            46: .Fl e
        !            47: option is specified).
        !            48: .Pp
        !            49: If any argument is a library, it is searched exactly once
        !            50: at the point it is encountered in the argument list.
        !            51: Only those routines defining an unresolved external
        !            52: reference are loaded.
        !            53: If a routine from a library
        !            54: references another routine in the library,
        !            55: and the library has not been processed by
        !            56: .Xr ranlib  1  ,
        !            57: the referenced routine must appear after the
        !            58: referencing routine in the library.
        !            59: Thus the order of programs within libraries
        !            60: may be important.
        !            61: The first member of a library
        !            62: should be a file named `\_\^\_.SYMDEF',
        !            63: which is understood to be a dictionary for the library as produced by
        !            64: .Xr ranlib  1  ;
        !            65: the dictionary is searched iteratively to satisfy as many references as
        !            66: possible.
        !            67: .Pp
        !            68: The symbols `\_etext', `\_edata' and `\_end'
        !            69: (`etext', `edata' and `end' in C)
        !            70: are reserved, and if referred to,
        !            71: are set to the first location above the program,
        !            72: the first location above initialized data,
        !            73: and the first location above all data respectively.
        !            74: It is erroneous to define these symbols.
        !            75: .Pp
        !            76: .Nm Ld
        !            77: understands several options.
        !            78: Except for
        !            79: .Fl l  ,
        !            80: they should appear before the file names.
        !            81: .Tw Ds
        !            82: .Tp Fl A
        !            83: This option specifies incremental loading, i.e.
        !            84: linking is to be done in a manner so that the resulting object
        !            85: may be read into an already executing program.
        !            86: The next argument is the name of a file whose symbol table will be
        !            87: taken as a basis on which to define additional symbols.
        !            88: Only newly linked material will be entered into the text and
        !            89: data portions of
        !            90: .Xr a.out ,
        !            91: but the new symbol table will reflect
        !            92: every symbol defined before and after the incremental load.
        !            93: This argument must appear before any other object file in the argument list.
        !            94: The
        !            95: .Fl T
        !            96: option may be used as well, and will be taken to mean that the
        !            97: newly linked segment will commence at the corresponding address
        !            98: (which must be a multiple of 1024).
        !            99: The default value is the old value of _end.
        !           100: .Tp Fl D
        !           101: Take the next argument as a hexadecimal number and pad the data segment
        !           102: with zero bytes to the indicated length.
        !           103: .Tp Fl d
        !           104: Force definition of common storage
        !           105: even if the
        !           106: .Fl r
        !           107: flag is present.
        !           108: .Tp Fl e
        !           109: The following argument is taken to be the
        !           110: name of the entry point of the loaded
        !           111: program; location 0 is the default.
        !           112: .Tc Fl L
        !           113: .Ar dir
        !           114: .Cx
        !           115: Add
        !           116: .Ar dir
        !           117: to the list of directories in which libraries are searched for.
        !           118: Directories specified with
        !           119: .Fl L
        !           120: are searched before the standard directories.
        !           121: .Tc Fl l
        !           122: .Ar x
        !           123: .Cx
        !           124: This
        !           125: option is an abbreviation for the library name
        !           126: .Sq Pa libx.a,
        !           127: where
        !           128: .Ar x
        !           129: is a string.
        !           130: .Nm Ld
        !           131: searches for libraries first in any directories
        !           132: specified with
        !           133: .Fl L
        !           134: options, then in the standard directories
        !           135: .Pa /lib ,
        !           136: .Pa /usr/lib ,
        !           137: and
        !           138: .Pa /usr/local/lib .
        !           139: A library is searched when its name is encountered,
        !           140: so the placement of a
        !           141: .Fl l
        !           142: is significant.
        !           143: .Tp Fl M
        !           144: produce a primitive load map, listing the names of the files
        !           145: which will be loaded.
        !           146: .Tp Fl N
        !           147: Do not make the text portion read only or sharable.  (Use "magic number" 0407.)
        !           148: .Tp Fl n
        !           149: Arrange (by giving the output file a 0410 "magic number") that
        !           150: when the output file is executed,
        !           151: the text portion will be read-only and shared
        !           152: among all users executing the file.
        !           153: This involves moving the data areas up to the first
        !           154: possible 1024 byte boundary following the
        !           155: end of the text.
        !           156: .Tp Fl o
        !           157: The
        !           158: .Ar name
        !           159: argument after
        !           160: .Fl o
        !           161: is used as the name of the
        !           162: .Nm ld
        !           163: output file, instead of
        !           164: .Pa a.out  .
        !           165: .Tp Fl r
        !           166: Generate relocation bits in the output file
        !           167: so that it can be the subject of another
        !           168: .Nm ld
        !           169: run.
        !           170: This flag also prevents final definitions from being
        !           171: given to common symbols,
        !           172: and suppresses the `undefined symbol' diagnostics.
        !           173: .Tp Fl S
        !           174: `Strip' the output by removing all symbols except locals and globals.
        !           175: .Tp Fl s
        !           176: `Strip' the output, that is, remove the symbol table
        !           177: and relocation bits to save space (but impair the
        !           178: usefulness of the debuggers).
        !           179: This information can also be removed by
        !           180: .Xr strip  1  .
        !           181: .Tp Fl T
        !           182: The next argument is a hexadecimal number which sets the text segment origin.
        !           183: The default origin is 0.
        !           184: .Tp Fl t
        !           185: ("trace")  Print the name of each file as it is processed.
        !           186: .Tp Fl u
        !           187: Take the following argument as a symbol and enter
        !           188: it as undefined in the symbol table.  This is useful
        !           189: for loading wholly from a library, since initially the symbol
        !           190: table is empty and an unresolved reference is needed
        !           191: to force the loading of the first routine.
        !           192: .Tp Fl X
        !           193: Save local symbols
        !           194: except for those whose names begin with `L'.
        !           195: This option is used by
        !           196: .Xr cc  1
        !           197: to discard internally-generated labels while
        !           198: retaining symbols local to routines.
        !           199: .Tp Fl x
        !           200: Do not preserve local
        !           201: (non-.globl) symbols in the output symbol table; only enter
        !           202: external symbols.
        !           203: This option saves some space in the output file.
        !           204: .Tc Fl y
        !           205: .Ar sym
        !           206: .Cx
        !           207: Indicate each file in which
        !           208: .Ar sym
        !           209: appears, its type and whether the file defines or references it.
        !           210: Many such options may be given to trace many symbols.
        !           211: (It is usually necessary to begin
        !           212: .Ar sym
        !           213: with an `_', as external C, FORTRAN and Pascal variables begin
        !           214: with underscores.)
        !           215: .Tp Fl z
        !           216: Arrange for the process to be loaded on
        !           217: demand from the resulting executable file (413 format)
        !           218: rather than preloaded.
        !           219: This is the default.
        !           220: Results in a 1024 byte header on the output file followed by
        !           221: a text and data segment each of which have size a multiple of 1024 bytes
        !           222: (being padded out with nulls in the file if necessary).
        !           223: With this format the first few BSS segment symbols may actually appear
        !           224: (from the output of
        !           225: .Xr size  1  )
        !           226: to live in the data segment;
        !           227: this to avoid wasting the space resulting from data segment size roundup.
        !           228: .Tp
        !           229: .Sh FILES
        !           230: .Dw /usr/local/lib/lib*.a
        !           231: .Di L
        !           232: .Dp Pa /usr/lib/lib*.a
        !           233: libraries
        !           234: .Dp Pa /usr/local/lib/lib*.a
        !           235: more libraries
        !           236: .Dp Pa a.out
        !           237: output file
        !           238: .Dp
        !           239: .Sh SEE ALSO
        !           240: .Xr as 1 ,
        !           241: .Xr ar 1 ,
        !           242: .Xr cc 1 ,
        !           243: .Xr ranlib 1
        !           244: .Sh HISTORY
        !           245: .Nm Ld
        !           246: appeared in Version 6 AT&T Unix.
        !           247: .Sh BUGS
        !           248: There is no way to force data to be page aligned.
        !           249: .Nm Ld
        !           250: pads images which are to be demand loaded from
        !           251: the file system to the next
        !           252: page boundary to avoid a bug in the system.

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