crt0_pa(3) crt0_pa(3)
For PA-RISC Systems
NAME [Toc] [Back]
crt0_pa: crt0.o, gcrt0.o, mcrt0.o - execution startup routines; PARISC
64-bit ELF uses crt0.o only
DESCRIPTION [Toc] [Back]
PA-RISC 32-bit SOM
The C, Pascal, and FORTRAN compilers link in the object files crt0.o,
gcrt0.o, or mcrt0.o to provide startup capabilities and environments
for program execution. All are identical except that gcrt0.o and
mcrt0.o provide additional functionality for gpro
profiling support respectively.
The following symbols are defined in these object files:
_environ An array of character pointers to the
environment in which the program will run.
This array is terminated by a null pointer.
_FPU_MODEL A variable of type short containing the FPU
model number returned by the FP status
instruction. This variable is initialized
with data from the kernel.
_FPU_REVISION A variable of type short containing the FPU
revision number returned by the FP status
instruction. This variable is initialized
with data from the kernel.
_CPU_KEYBITS_1 A variable of type int containing CPU
specific information. This variable is
initialized with data from the kernel.
_CPU_REVISION A variable of type int containing the CPU
revision of the machine. This variable is
initialized with data from the kernel.
_SYSTEM_ID A variable of type int containing the system
id value for an executable program.
$START$ Execution start address.
_start A secondary startup routine for C programs,
called from $START$, which in turn calls
main. This routine is contained in the C
library rather than the crt0.o file. For
Pascal and FORTRAN programs, this symbol
labels the beginning of the outer block (main
program) and is generated by the compilers.
$global$ The initial address of the program's data
pointer. The startup code loads this address
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: Sep 2004
crt0_pa(3) crt0_pa(3)
For PA-RISC Systems
into general register 27.
$UNWIND_START The beginning of the stack unwind table.
$UNWIND_END The end of the stack unwind table.
$RECOVER_START The beginning of the try/recover table.
$RECOVER_END The end of the try/recover table.
The crt0.o file defines a null procedure for _mcount, so programs
compiled with profiling can be linked without profiling.
The linker defines the following two symbols:
__text_start The beginning address of the program's text
area.
__data_start The beginning address of the program's data
area.
PA-RISC 64-bit ELF [Toc] [Back]
The C, Pascal, and FORTRAN compilers link in the object file crt0.o to
provide startup capabilities and environments for program execution.
It contains startup code that must be linked using ld to every -
noshared PA-RISC 64-bit program. In a -dynamic program, the crt0.o
object file is not used, and all actions normally associated with it
are instead done by the dynamic loader dld.sl(5). Additional
functionality for prof(1) and gprof(1) profiling support is no longer
handled by crt0.o.
In a PA-RISC 64-bit environment, crt0.o processes initializers and
terminators. Initializers are routines that are called before the
program entry point and terminators are routines that are called when
the program terminates via the exit routine. Initializers are invoked
in reverse order of the link line so that dependent libraries are
initialized before the libraries that depend on them. Terminators, on
the other hand, are invoked in the forward order.
Unlike the SOM version of crt0.o, crt0.o for PA-RISC 64-bit ELF does
not define any variables. It, however, sets the following global
variables:
__argc A variable of type long containing the number
of arguments.
__argv An array of character pointers to the
arguments themselves.
_environ, __envp An array of character pointers to the
environment in which the program will run.
This array is terminated by a null pointer.
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: Sep 2004
crt0_pa(3) crt0_pa(3)
For PA-RISC Systems
_CPU_KEYBITS_1 A variable of type int containing CPU
specific information. This variable is
initialized with data from the kernel.
_FPU_MODEL A variable of type long containing the FPU
model number returned by the FP status
instruction. This variable is initialized
with data from the kernel.
_FPU_REVISION A variable of type long containing the FPU
revision number returned by the FP status
instruction. This variable is initialized
with data from the kernel.
_CPU_REVISION A variable of type long containing the CPU
revision of the machine. This variable is
initialized with data from the kernel.
_SYSTEM_ID A variable of type long containing the system
id value for an executable program.
__tls_size A variable of type long containing the
requested thread local storage size. This
variable is initialized with data from the
kernel.
__load_info A variable of type void * containing load
information passed from the kernel.
AUTHOR [Toc] [Back]
The features described in this entry originated from AT&T UNIX System
III.
FILES [Toc] [Back]
crt0.h
SEE ALSO [Toc] [Back]
Profiling and Debugging Tools
gprof(1) display call graph profile data
monitor(3C) prepare execution profile
prof(1) display profile data
profil(2) execution time profile
System Tools
cc(1) invoke the HP-UX C compiler
exec(2) execute a file
f77(1) invoke the HP-UX FORTRAN compiler
ld(1) invoke the link editor
dld.sl(5) the PA-RISC dynamic loader
pc(1) invoke the HP-UX Pascal compiler
Miscellaneous
Hewlett-Packard Company - 3 - HP-UX 11i Version 2: Sep 2004
crt0_pa(3) crt0_pa(3)
For PA-RISC Systems
end(3C) symbol of the last locations in program
Hewlett-Packard Company - 4 - HP-UX 11i Version 2: Sep 2004 [ Back ] |
