end, _end, _ebss, etext, _etext, edata, _edata, eprol,
_ftext, _fdata, _fbss, _procedure_table, _procedure_table_size,
_procedure_string_table, __istart,
__fstart, _DYNAMIC, _DYNAMIC_LINK, _BASE_ADDRESS,
_GOT_OFFSET, _cobol_main - locations in program and definitions
in run-time procedure table
extern unsigned long end; extern unsigned long _end;
extern unsigned long _ebss;
/* First address above a program's */
/* uninitialized data region */
extern unsigned long etext; extern unsigned long _etext;
/* First address above the text region */
extern unsigned long edata; extern unsigned long _edata;
/* First address above the initialized */
/* data region */
extern unsigned long eprol;
/* First instruction of the user's program */
/* that follows the run-time startup routine */
extern unsigned long _ftext;
/* Start address of the text region */
extern unsigned long _fdata;
/* First address of the initialized data */
/* region */
extern unsigned long _fbss;
/* Start address of the uninitialized data */
/* region */
extern unsigned long _procedure_table; extern unsigned
long _procedure_table_size; extern unsigned long _procedure_string_table;
/* See under DESCRIPTION */
extern unsigned long __istart;
/* Start address of the program's */
/* initialization function driver routine */
extern unsigned long __fstart;
/* Start address of the program's */
/* termination function driver routine */
extern unsigned long _DYNAMIC;
/* Address of a shared object's dynamic */
/* header table */
extern unsigned long _DYNAMIC_LINK;
/* Identifies the link type of a program */
/* or shared library: 0 for non_shared, */
/* 1 for call_shared, and 2 for shared */
extern unsigned long _BASE_ADDRESS;
/* First mapped address of a program or */
/* shared library */
extern unsigned long _GOT_OFFSET;
/* Address of the global offset table in */
/* a shared program or shared library */
extern unsigned long _cobol_main
/* Address of the main routine in a cobol */
/* program */
extern unsigned long __EXEC_FLAGS;
/* Identifies link-time attributes of an */
/* executable (such as __EXEC_FLAG_TASO for */
/* executables linked with the -taso option). */
/* The value of this symbol is a bit mask. */
/* See /usr/include/filehdr.h for supported */
/* options. */
These names refer neither to routines nor to locations
with interesting contents except for _procedure_table,
_procedure_string_table, and, for Tru64 UNIX, __istart and
__fstart. Except for eprol, these are all names of linkerdefined
symbols.
Note that the end, etext, and edata symbols are not
defined when you compile in ANSI mode.
When execution begins, the program break coincides with
_end, but it is modified by the routines brk(2) and
sbrk(2), which are used by malloc(3). The current value of
the program break is reliably returned by "sbrk(0)".
The linker-defined symbols _procedure_table, _procedure_table_size,
and _procedure_string_table refer to the
data structures of the run-time procedure table. Because
these are linker-defined symbols, the data structures are
built by ld(1) only if they are referenced.
See the include file sym.h for the definition of the runtime
procedure table, and see the include file exception.h
for its uses.
These symbols are all absolute symbols; the value of each
symbol is its address (for example, &_procedure_table_size).
Any reference to the symbol itself will
attempt to access the symbol's value as if it were a valid
address and will most likely result in an access violation.
All of these symbols except for end, _end, eprol,
__istart, and _cobol_main are defined as local symbols in
an executable or shared library's dynamic symbol table.
Consequently, an executable or shared library can only
reference its own definitions of these local symbols.
brk(2), malloc(3)
end(3)
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