man/ld86.1


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.TH ld86 1 "Apr, 1997"
.BY Bruce Evans
.nh
.SH NAME
ld86 \- Linker for as86(1)
.SH SYNOPSIS
.BR ld86
.RB [ -03MNdimrstyz [-]]
.RB [ -llib_extension ]
.RB [ -o\ outfile ]
.RB [ -Ccrtfile ]
.RB [ -Llibdir ]
.RB [ -Olibfile ]
.RB [ -Ttextaddr ]
.RB [ -Hheapsize ]
.RB [ -Ddataaddr ]
.B infile...

.SH DESCRIPTION
This linker understands only the object files produced by the as86 assembler,
it can link them into either an impure or a separate I&D executable.

The linking defaults are everything off or none except for
.B -0
and the output file is
.BR a.out .
There is
.I not
a standard library location defined in the linker.

.SH OPTIONS
.TP
.B -0
produce header with 16-bit magic
.\"and use library subdir i86 for -lx
.TP
.B -3
produce header with 32-bit magic
.\"and use library subdir i386 for -lx
.TP
.B -7
produce Seventh Edition UNIX a.out header.
.TP
.B -d
delete the header from the output file, used for MSDOS COM files. As a side
effect this also includes -s as there's nowhere to put a symbol table.
.TP
.B -Cx
add file libdir-from-search/crtx.o to list of files linked
.TP
.B -D
data base address follows (in format suitable for strtoul)
.TP
.B -H
the top of heap (initial stack) address (in format suitable for strtoul)
.TP
.B -Lx
add dir name x to the head of the list of library dirs searched
.TP
.B -M
print symbols linked on stdout
.TP
.B -N
Create a native Linux OMAGIC output file. If the contents are i386 code the
binary can be either linked by GCC or executed by linux. If the
.B -z
option is also included the linker can generate a QMAGIC executable.
.TP
.B -Ox
add library or object file libdir-from-search/x to list of files linked
.TP
.B -T
text base address follows (in format suitable for strtoul)
.TP
.B -i
separate I&D output
.TP
.B -lx
add library libdir-from-search/libx.a to list of files linked
.TP
.B -m
print modules linked on stdout
.TP
.B -o
output file name follows
.TP
.B -s
strip symbols
.TP
.B -r
Generate a relocatable object from one source object, if the linker is
given the -N option also the output format will be the hosts native format
if possible.
.TP
.B -t
trace modules being looked at on stdout
.TP
.B -y
Alter the symbol tables to add label 'extensions' so that labels with
more than 8 characters can be stored in elks executables.
.TP
.B -z
produce "unmapped zero page" or "QMAGIC" executables
.P
All the options not taking an argument may be turned off by following the
option letter by a '-', as for cc1.
.SH PREDEFINED LABELS
The linker predefines several labels that can be imported into user programs.
.TP
.B __etext
Standard C variable for the end of the text segment.
.TP
.B __edata
Standard C variable for the end of the initilised data.
.TP
.B __end
Standard C variable for the end of the bss area.
.TP
.B __segoff
The offset within the executable file between the start of the text segment
and the start of the data segment in 16 byte 'paragraphs'. Note this is
.B zero
for impure (tiny model) executables and is adjusted for executables that
don't start at offset 0 within the segment.
.TP
.B __segXDL
The lowest address with data in segment 'X'. (eg __seg0DL is for segment zero
or the text segment, __seg3DL is for the data segment)
The value 'X' is a hex digit.
.TP
.B __segXDH
The top of segment 'X's data area.
.TP
.B __segXCL
The bottom of segment 'X's 'common data' or unitilised data area. Each 
segment has both an initilised and unitilised data area.
.TP
.B __segXCH
The top of segment 'X's common area.
.TP
.B __segXSO
This is the adjusted offset from segment 0 of the start of segment 'X'
in 'paragraphs'.

.SH HISTORY

The 6809 version does not support -i.

The previous versions of the linker could produce an 8086 executable with
segments of a size >64k, now only i386 executables may have segments
this large.

.SH BUGS
The linker cannot deal with reverse seeks caused by
.B org
instructions in the object file. Unlike previous versions the current one
traps the error rather than trying to fill up the hard disk.

The linker produces a broken a.out object file if given one input and the
.B -r
option this is so it is compatible with pre-dev86 versions.