blob: 1780f76206e3d884a5329caeba59a36dbce26fe0 [file] [log] [blame]
This is, produced by makeinfo version 4.0 from ./ld.texinfo.
* Ld: (ld). The GNU linker.
This file documents the GNU linker LD version 2.11.2.
Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free
Software Foundation, Inc.

File:, Node: Bug Criteria, Next: Bug Reporting, Up: Reporting Bugs
Have you found a bug?
If you are not sure whether you have found a bug, here are some
* If the linker gets a fatal signal, for any input whatever, that is
a `ld' bug. Reliable linkers never crash.
* If `ld' produces an error message for valid input, that is a bug.
* If `ld' does not produce an error message for invalid input, that
may be a bug. In the general case, the linker can not verify that
object files are correct.
* If you are an experienced user of linkers, your suggestions for
improvement of `ld' are welcome in any case.

File:, Node: Bug Reporting, Prev: Bug Criteria, Up: Reporting Bugs
How to report bugs
A number of companies and individuals offer support for GNU
products. If you obtained `ld' from a support organization, we
recommend you contact that organization first.
You can find contact information for many support companies and
individuals in the file `etc/SERVICE' in the GNU Emacs distribution.
Otherwise, send bug reports for `ld' to `'.
The fundamental principle of reporting bugs usefully is this:
*report all the facts*. If you are not sure whether to state a fact or
leave it out, state it!
Often people omit facts because they think they know what causes the
problem and assume that some details do not matter. Thus, you might
assume that the name of a symbol you use in an example does not matter.
Well, probably it does not, but one cannot be sure. Perhaps the bug is
a stray memory reference which happens to fetch from the location where
that name is stored in memory; perhaps, if the name were different, the
contents of that location would fool the linker into doing the right
thing despite the bug. Play it safe and give a specific, complete
example. That is the easiest thing for you to do, and the most helpful.
Keep in mind that the purpose of a bug report is to enable us to fix
the bug if it is new to us. Therefore, always write your bug reports
on the assumption that the bug has not been reported previously.
Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?" Those bug reports are useless, and we urge everyone to _refuse
to respond to them_ except to chide the sender to report bugs properly.
To enable us to fix the bug, you should include all these things:
* The version of `ld'. `ld' announces it if you start it with the
`--version' argument.
Without this, we will not know whether there is any point in
looking for the bug in the current version of `ld'.
* Any patches you may have applied to the `ld' source, including any
patches made to the `BFD' library.
* The type of machine you are using, and the operating system name
and version number.
* What compiler (and its version) was used to compile `ld'--e.g.
* The command arguments you gave the linker to link your example and
observe the bug. To guarantee you will not omit something
important, list them all. A copy of the Makefile (or the output
from make) is sufficient.
If we were to try to guess the arguments, we would probably guess
wrong and then we might not encounter the bug.
* A complete input file, or set of input files, that will reproduce
the bug. It is generally most helpful to send the actual object
files, uuencoded if necessary to get them through the mail system.
Making them available for anonymous FTP is not as good, but may
be the only reasonable choice for large object files.
If the source files were assembled using `gas' or compiled using
`gcc', then it may be OK to send the source files rather than the
object files. In this case, be sure to say exactly what version of
`gas' or `gcc' was used to produce the object files. Also say how
`gas' or `gcc' were configured.
* A description of what behavior you observe that you believe is
incorrect. For example, "It gets a fatal signal."
Of course, if the bug is that `ld' gets a fatal signal, then we
will certainly notice it. But if the bug is incorrect output, we
might not notice unless it is glaringly wrong. You might as well
not give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should
still say so explicitly. Suppose something strange is going on,
such as, your copy of `ld' is out of synch, or you have
encountered a bug in the C library on your system. (This has
happened!) Your copy might crash and ours would not. If you told
us to expect a crash, then when ours fails to crash, we would know
that the bug was not happening for us. If you had not told us to
expect a crash, then we would not be able to draw any conclusion
from our observations.
* If you wish to suggest changes to the `ld' source, send us context
diffs, as generated by `diff' with the `-u', `-c', or `-p' option.
Always send diffs from the old file to the new file. If you even
discuss something in the `ld' source, refer to it by context, not
by line number.
The line numbers in our development sources will not match those
in your sources. Your line numbers would convey no useful
information to us.
Here are some things that are not necessary:
* A description of the envelope of the bug.
Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.
This is often time consuming and not very useful, because the way
we will find the bug is by running a single example under the
debugger with breakpoints, not by pure deduction from a series of
examples. We recommend that you save your time for something else.
Of course, if you can find a simpler example to report _instead_
of the original one, that is a convenience for us. Errors in the
output will be easier to spot, running under the debugger will take
less time, and so on.
However, simplification is not vital; if you do not want to do
this, report the bug anyway and send us the entire test case you
* A patch for the bug.
A patch for the bug does help us if it is a good one. But do not
omit the necessary information, such as the test case, on the
assumption that a patch is all we need. We might see problems
with your patch and decide to fix the problem another way, or we
might not understand it at all.
Sometimes with a program as complicated as `ld' it is very hard to
construct an example that will make the program follow a certain
path through the code. If you do not send us the example, we will
not be able to construct one, so we will not be able to verify
that the bug is fixed.
And if we cannot understand what bug you are trying to fix, or why
your patch should be an improvement, we will not install it. A
test case will help us to understand.
* A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even we cannot guess right about
such things without first using the debugger to find the facts.

File:, Node: MRI, Next: GNU Free Documentation License, Prev: Reporting Bugs, Up: Top
MRI Compatible Script Files
To aid users making the transition to GNU `ld' from the MRI linker,
`ld' can use MRI compatible linker scripts as an alternative to the
more general-purpose linker scripting language described in *Note
Scripts::. MRI compatible linker scripts have a much simpler command
set than the scripting language otherwise used with `ld'. GNU `ld'
supports the most commonly used MRI linker commands; these commands are
described here.
In general, MRI scripts aren't of much use with the `a.out' object
file format, since it only has three sections and MRI scripts lack some
features to make use of them.
You can specify a file containing an MRI-compatible script using the
`-c' command-line option.
Each command in an MRI-compatible script occupies its own line; each
command line starts with the keyword that identifies the command (though
blank lines are also allowed for punctuation). If a line of an
MRI-compatible script begins with an unrecognized keyword, `ld' issues
a warning message, but continues processing the script.
Lines beginning with `*' are comments.
You can write these commands using all upper-case letters, or all
lower case; for example, `chip' is the same as `CHIP'. The following
list shows only the upper-case form of each command.
Normally, `ld' includes in the output file all sections from all
the input files. However, in an MRI-compatible script, you can
use the `ABSOLUTE' command to restrict the sections that will be
present in your output program. If the `ABSOLUTE' command is used
at all in a script, then only the sections named explicitly in
`ABSOLUTE' commands will appear in the linker output. You can
still use other input sections (whatever you select on the command
line, or using `LOAD') to resolve addresses in the output file.
Use this command to place the data from input section IN-SECNAME
in a section called OUT-SECNAME in the linker output file.
IN-SECNAME may be an integer.
Align the section called SECNAME to EXPRESSION. The EXPRESSION
should be a power of two.
Use the value of EXPRESSION as the lowest address (other than
absolute addresses) in the output file.
This command does nothing; it is accepted only for compatibility.
This command does nothing whatever; it's only accepted for
Similar to the `OUTPUT_FORMAT' command in the more general linker
language, but restricted to one of these output formats:
1. S-records, if OUTPUT-FORMAT is `S'
3. COFF (the `coff-m68k' variant in BFD), if OUTPUT-FORMAT is
Print (to the standard output file) a link map, as produced by the
`ld' command-line option `-M'.
The keyword `LIST' may be followed by anything on the same line,
with no change in its effect.
Include one or more object file FILENAME in the link; this has the
same effect as specifying FILENAME directly on the `ld' command
OUTPUT-NAME is the name for the program produced by `ld'; the
MRI-compatible command `NAME' is equivalent to the command-line
option `-o' or the general script language command `OUTPUT'.
Normally, `ld' orders the sections in its output file in the order
in which they first appear in the input files. In an
MRI-compatible script, you can override this ordering with the
`ORDER' command. The sections you list with `ORDER' will appear
first in your output file, in the order specified.
Supply a value (EXPRESSION) for external symbol NAME used in the
linker input files.
You can use any of these three forms of the `SECT' command to
specify the start address (EXPRESSION) for section SECNAME. If
you have more than one `SECT' statement for the same SECNAME, only
the _first_ sets the start address.

File:, Node: GNU Free Documentation License, Next: Index, Prev: MRI, Up: Top
GNU Free Documentation License
GNU Free Documentation License
Version 1.1, March 2000
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