crt0_pa.3 (2010 09)

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crt0_pa(3)

PA-RISC Systems Only

crt0_pa(3)

NAME

crt0_pa: crt0.o, gcrt0.o, mcrt0.o - execution startup routines for PA-RISC systems

SYNOPSIS

Remarks

PA-RISC 64-bit ELF uses

crt0.o only.

This manpage describes

crt0.o on PA-RISC systems. For

crt0.o on Integrity systems, see crt0_ia (3).

DESCRIPTION

PA-RISC 32-bit SOM

The C, Pascal, and FORTRAN compilers link in the object ﬁles

crt0.o, gcrt0.o,or mcrt0.o to pro-

vide startup capabilities and environments for program execution. All are identical except that

gcrt0.o

and mcrt0.o provide additional functionality for gprof (1) and prof (1) 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 vari-

able is initialized with data from the kernel.

_SYSTEM_ID A variable of type int containing the system id value for an executable pro-

gram.

$START$ 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 com-

pilers.

$global$ The initial address of the program’s data pointer. The startup code loads this

address 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

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 func-

tionality 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 rou-

tines 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

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
crt0_pa(3) crt0_pa(3) PA-RISC Systems Only NAME crt0_pa: crt0.o, gcrt0.o, mcrt0.o - execution startup routines for PA-RISC systems SYNOPSIS Remarks PA-RISC 64-bit ELF uses crt0.o only. This manpage describes crt0.o on PA-RISC systems. For crt0.o on Integrity systems, see crt0_ia (3). DESCRIPTION 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.
PAGE 2
crt0_pa(3) crt0_pa(3) PA-RISC Systems Only 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.