Date: Sun, 16 May 1999 13:54:44 +0200 From: Ugo Matrangolo <gimatra@tin.it> To: freebsd-questions@freebsd.org Subject: newbie : gdb and 386's machine code Message-ID: <373EB204.BD1DE491@tin.it>
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Hi ,
Cause i have to do some coding in 'pure' assembly language (college exam) i
have to find a way to write pure x86 code under freebsd .
Now , i can easily write asm code using nasm and run it using this C code
that wraps my asm program :
#include <stdio.h>
extern void start(void);
int main(void)
{
start();
return 0;
}
... and this is a sample asm code :
; hello.s -- Simple test program .
BITS 32
GLOBAL start ; exported syms
EXTERN printf ; imported syms
SECTION .text
start:
push ebp
mov esp,ebp
push dword hello_string
call printf
add esp,4
mov ebp,esp
pop ebp
ret
SECTION .data
hello_string db "Hello World!",10,0
SECTION .bss
After compiling this with nasm & gcc ,it runs fine . Now , what if
i want to debug the asm code instruction by instruction ?
If i use gdb,placing a breakpoint on start(),"step"/"next" jumps over the start() routine !
All i can do ( i think ! )is to put a breakpoint in memory ,run the code,
and see what are the registers but i don't know how to execute every single
instructions .
How can i do it using gdb or any other debugger (?) under freebsd ?
Please , i don't want to reinstall dos on my box !;-)
bye!
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