Appendix A 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 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
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.
- Normally, ld includes in the output file all sections from all
the input files. However, in an MRI-compatible script, you can use the
ABSOLUTEcommand to restrict the sections that will be present in your output program. If the
ABSOLUTEcommand is used at all in a script, then only the sections named explicitly in
ABSOLUTEcommands 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 compatibility.
- Similar to the
OUTPUT_FORMATcommand in the more general linker language, but restricted to one of these output formats:
- S-records, if output-format is S
- IEEE, if output-format is IEEE
- COFF (the coff-m68k variant in BFD), if output-format is COFF
- Print (to the standard output file) a link map, as produced by the
ld command-line option -M.
LISTmay 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 line.
- output-name is the name for the program produced by ld; the
NAMEis equivalent to the command-line option -o or the general script language command
ORDERsecname secname secname
- 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
ORDERcommand. The sections you list with
ORDERwill 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
SECTcommand to specify the start address (expression) for section secname. If you have more than one
SECTstatement for the same secname, only the first sets the start address.