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1.1 root 1: .\" @(#) ld.1: 2.3 11/17/83
2: .ds ZZ DEVELOPMENT PACKAGE
3: .TH MC68LD 1 "630 MTG"
4: .SH NAME
5: mc68ld \- link editor for MC68000 object files
6: .SH SYNOPSIS
7: \f3mc68ld [\f1 options \f3]\f1 file-names
8: .SH DESCRIPTION
9: The
10: .I mc68ld
11: command
12: combines several
13: object files into one,
14: performs relocation,
15: resolves external symbols,
16: and supports symbol table information
17: for symbolic debugging.
18: In the simplest case, the names of several object
19: programs are given, and
20: .I mc68ld
21: combines them, producing
22: an object module that can either be executed or
23: used as input for a subsequent
24: .I mc68ld
25: run.
26: The output of
27: .I mc68ld
28: is left in
29: .BR mc68a.out .
30: This file is executable
31: if no errors occurred during the load.
32: If any input file,
33: .IR file-name ,
34: is not an object file,
35: .I mc68ld
36: assumes it is either a text file containing link editor directives
37: or an archive library.
38: (See
39: the \f2Link Editor\f1 in the \f2UNIX System V Support Tools
40: Guide\f1 for a discussion of input directives.)
41: .PP
42: If any argument is a library, it is searched exactly once
43: at the point it is encountered in the argument list.
44: Only those routines defining an unresolved external
45: reference are loaded.
46: The order of library members is unimportant because
47: \fImc68ld\fR passes through each library's (archive) symbol
48: table as many times as necessary until no new
49: external symbols are resolved and no new references are generated.
50: .PP
51: The following options are recognized by
52: .IR mc68ld .
53: .TP \w'\fB\-u\fP\ symname\ \ 'u
54: .if !'mc68'' \{\
55: .B \-a
56: Produces an absolute file; gives warnings for undefined references.
57: Relocation information is stripped from the output object file
58: unless the
59: .B \-r
60: option is given. The
61: .B \-r
62: option is needed only when an absolute file should retain its
63: relocation information (the normal case for the 630 MTG
64: downloaded programs).
65: If neither
66: .BR \-a " nor " \-r
67: is given,
68: .B \-a
69: is assumed.
70: \}
71: .TP
72: .BR \-e " epsym"
73: Sets the default entry point address for the output file to be that of
74: the symbol
75: .IR epsym .
76: .if \nF \{\
77: This option forces the
78: .B \-X
79: option to be set. \}
80: .TP
81: .BR \-f " fill"
82: Sets the default fill pattern for ``holes'' within
83: an output section as well as initialized bss sections.
84: The argument \fIfill\fP is a two-byte constant.
85: .if 'mc68'b16' \{\
86: .TP
87: .B \-i
88: This option specifies that separate ``I'' and ``D'' space are to be
89: generated.
90: .B \-i
91: has no effect if
92: .B \-tv
93: is given.
94: This allows 64K of instructions and 64K of data.
95: 'br \}
96: .if 'mc68'x86' \{\
97: .TP
98: .B \-i
99: This option specifies that separate ``I'' and ``D'' space is to be
100: generated.
101: The option
102: .B \-i
103: has no effect if
104: .B \-tv
105: is given.
106: This allows up to 1 MB of text and 1 MB of data.
107: 'br \}
108: .ie \nD \{\
109: .TP
110: .BR \-l "x"
111: Searchs a library
112: .BI lib x .a,
113: where \fIx\fR is up to seven characters.
114: A library is searched when its name is encountered,
115: so the placement of a \fB\-l\fR
116: is significant.
117: By default, libraries are located in
118: .ie 'mc68''
119: .BR /lib.
120: .el $DMD/lib.
121: 'br \}
122: .el \{\
123: .TP
124: .BI \-l x
125: Searches a library
126: .BI lib x .a,
127: where \fIx\fR is up to seven characters.
128: A library is searched when its name is encountered,
129: so the placement of a \fB\-l\fR
130: is significant.
131: By default, libraries are located in
132: .ie 'mc68'' /lib and /usr/lib.
133: .el $DMD/lib .
134: 'br \}
135: .TP
136: .B \-m
137: Produces a map or listing of the input/output sections
138: on the standard output.
139: .TP
140: .BR \-o " outfile"
141: Produces an output object file by the name
142: .IR outfile .
143: The name of the default object file is
144: .BR mc68a.out .
145: .TP
146: .B \-r
147: Retains relocation entries in
148: the output object file.
149: Relocation entries must be saved if the
150: output file is to become an input file in a
151: subsequent
152: .I mc68ld
153: run.
154: .ie 'mc68'' The
155: .el \{\
156: Unless
157: .B \-a
158: is also given, the
159: \}
160: link editor will not complain about
161: unresolved references.
162: .TP
163: .B \-s
164: Strips line number entries and
165: symbol table information
166: from the output object file.
167: .if \nG \{\
168: .TP
169: .B \-t
170: Turns off the warning about multiply defined symbols that are
171: not the same size.
172: 'br \}
173: .if \nC \{\
174: .TP
175: .B \-tv
176: Transfer vector object files are expected.
177: When libraries are searched with this option,
178: component object modules with the wrong magic
179: number are ignored (as are transfer vector modules
180: when
181: .B \-tv
182: is not given).
183: The default is
184: .I no
185: transfer vectors.
186: 'br \}
187: .TP
188: .BR \-u " symname"
189: Enters \fIsymname\fP as an undefined symbol
190: in the symbol table.
191: This is useful
192: for loading entirely from a library, since initially the symbol
193: table is empty and an unresolved reference is needed
194: to force the loading of the first routine.
195: .\" .if \nG \{\
196: .\" .TP
197: .\" .B \-x
198: .\" Do not preserve local (non-.globl) symbols in the output symbol
199: .\" table; enter external and static symbols only. This option saves
200: .\" some space in the output file.
201: .\" 'br \}
202: .if \nH \{\
203: .TP
204: .B \-z
205: Do not bind anything to address zero. This option will catch null
206: pointers.
207: .TP
208: .B \-F
209: Allows the object module to be paged.
210: 'br \}
211: .TP
212: .BR \-L " dir"
213: Changes the algorithm of searching for
214: .BI lib x .a
215: to look in
216: .IR dir
217: before looking in $DMD/lib.
218: This option is effective only if it precedes the
219: .B \-l
220: option on the command line.
221: .if \nG \{\
222: .TP
223: .B \-M
224: Outputs a message for each multiply defined external definition.
225: 'br \}
226: .TP
227: .B \-N
228: Puts the data section immediately following the text in the output file.
229: .TP
230: .B \-V
231: Outputs a message giving information about the version of mc68ld
232: being used.
233: .TP
234: .BR \-VS " num"
235: Uses
236: \f2num\f1
237: as a decimal version stamp
238: identifying the
239: .BR mc68a.out
240: file that is produced. The version
241: stamp is stored in the optional header.
242: .if \nF \{\
243: .TP
244: .B \-X
245: Generates a standard UNIX file header within the ``optional header''
246: field in the output file.
247: 'br \}
248: .DT
249: .br
250: .DT
251: .SH FILES
252: .PD 0
253: .TP 25
254: .ie 'mc68'' /lib/lib\fI?\fR.a
255: .el $DMD/lib/lib\fI?\fR.a
256: libraries
257: .if 'mc68'' \{\
258: .TP 25
259: /usr/lib/lib?.a
260: libraries
261: \}
262: .TP 25
263: mc68a.out
264: output file
265: .PD
266: .SH "SEE ALSO"
267: dmdcc(1), mc68as(1).
268: .br
269: a.out(4), ar(4) in the \f2UNIX System V Programmer's
270: Reference Manual\f1.
271: .bp
272: .SH WARNINGS
273: Through its options and input directives, the Motorola 68000 link editor gives
274: users great flexibility;
275: however, those who use the input directives must assume
276: some added responsibilities.
277: Input directives and options should insure the following properties
278: for programs:
279: .if 'mc68'b16' \{\
280: .IP \- 5
281: C programs must have data
282: .RB ( .data "), bss (" .bss ),
283: and stack space in one 64K byte region.
284: Stack space
285: .I must
286: be provided.
287: 'br \}
288: .IP \- 5
289: C defines a zero pointer as null.
290: A pointer to which zero has been assigned must
291: not point to any object.
292: To satisfy this, users must not place any object
293: at virtual address zero in the data space.
294: .tr ~
295: .IP \- 5
296: When the link editor is called through
297: .IR dmdcc (1),
298: a startup routine is linked with the user's program. This
299: routine usually calls exit(~) [see
300: .IR exit (3R)]
301: after execution of the main program. If the user
302: calls the link editor directly, then the user must insure that
303: the program always calls exit(~) rather than falling through the
304: end of the entry routine.
305: .if 'mc68'b16' \{\
306: .IP \- 5
307: Without a transfer vector, all text (code)
308: must reside within a single 64K-byte area.
309: Transfer vector function linkage removes this
310: restriction.
311: .PP
312: By default, the link editor takes care of these
313: things.
314: Specifying regions or defining sections with names other
315: than
316: .BR .bss ", " .data ", " .text ", or"
317: .B .tv
318: can decrease the link editor's ability to do these
319: automatically.
320: In general, users should not specify regions when the
321: program uses a transfer vector.
322: 'br \}
323: .if \nC \{\
324: .SH BUGS
325: .I mc68ld
326: can not currently create transfer vector symbols.
327: Thus no symbols created through assignment in an
328: input directive will be given an entry in the transfer vector.
329: In particular, this means the entry point of a program
330: can not be redefined by assignment to
331: .BR main .
332: Unsuspecting users who create such a symbol and expect it
333: to be in the transfer vector receive an obscure error
334: message about an invalid transfer vector relocation reference.
335: 'br \}
336: .PP
337: The
338: \f3\-VS\f1 \f2num\f1
339: option has an effect only when the
340: .B "\-X"
341: option is also selected.
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