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SubjectAddress of .globl _start
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Hello,

I have compiled test.s (bellow) with 'as' compiler:

-------------------------------------------------
.section .data

.globl var
var:
.long 10

.section .text

.globl _start
_start:
movl $_start, %ebx
jmp loop_exit

loop_exit:
movl $1, %eax #1 is the exit() syscall
int $0x80

-------------------------------------------------
and got output with echo $? (reads %ebx register)
116

After that I compiled test.s (bellow) with 'as' compiler:

-------------------------------------------------
.section .data

.globl var
var:
.long 10

.section .text

.globl _start
_start:
movl _start, %ebx
jmp loop_exit

loop_exit:
movl $1, %eax #1 is the exit() syscall
int $0x80

-------------------------------------------------
and got output with echo $? (reads %ebx register)
139

After that I compiled test.s (bellow) with 'as' compiler:

-------------------------------------------------
.section .data

.globl var
var:
.long 10

.section .text

.globl _start
_start:
movl var, %ebx
jmp loop_exit

loop_exit:
movl $1, %eax #1 is the exit() syscall
int $0x80

-------------------------------------------------
and got output with echo $? (reads %ebx register)
10

After that I compiled test.s (bellow) with 'as' compiler:

-------------------------------------------------
.section .data

.globl var
var:
.long 10

.section .text

.globl _start
_start:
movl $var, %ebx
jmp loop_exit

loop_exit:
movl $1, %eax #1 is the exit() syscall
int $0x80

-------------------------------------------------
and got output with echo $? (reads %ebx register)
132

So my question is, what these numbers mean ? From which
point in memory they are counted from ? From this I can conclude
that value for "movl _start, %ebx" is always 139 and it can be on
various addresses. Is this means that beginning of 'as' assembly program is
signed with value 139 ???

thanks,

Dragoslav Zaric,
[Programmer; M Sc Astrophysics]


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