Author Topic: Producing a beep with int 10h in Linux  (Read 6935 times)

nobody

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Producing a beep with int 10h in Linux
« on: February 01, 2005, 09:17:19 AM »
Hi
I want to produce a beep with int 10h
and function 0eh in Linux.
I try to print ascii 7 which is the bel
and everytime I run the file - I get a Segmentation fault...
I dont understand, it should be fairly simple  

Here's my code:

section .data
section .text
        global _start

_start:
        mov ah,0eh       ; Write Text in Teletype Mode
        mov al,7           ; the bell ascii
        mov bl,0           ; foreground pixel color
        mov bh,0          ; page number

int 10h              ; Call the kernel

mov eax,1            ; The system call for exit (sys_exit)
        mov ebx,0            ; Exit with return code of 0 (no error)
        int 80h

that's it...

Here's how i compile it, in case I make the mistake here:
#nasm -f elf beep.asm
#ld -s -o beep beep.o

and when i run it:
#./beep
I get:
Segmentation fault

Please help...
10x

nobody

  • Guest
Re: Producing a beep with int 10h in Linux
« Reply #1 on: February 01, 2005, 11:16:08 AM »
I'm new to this myself, but I think BIOS interrupts can't be accessed in protected mode. Not sure on it, though..

nobody

  • Guest
Re: Producing a beep with int 10h in Linux
« Reply #2 on: February 01, 2005, 12:58:16 PM »
Yes, you can not access to BIOS interruptions because
the OS does not use a real mode interrupt vector.

You would have to switch to kernel mode and change
the IDT (Interrupt Descriptor Table). Is very complex
and danger.

Maybe, write a kernel module to add a new entry in
the IDT.

-----
nmt

Offline Frank Kotler

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Re: Producing a beep with int 10h in Linux
« Reply #3 on: February 01, 2005, 04:01:01 PM »
Yeah... the problem with int 10h (or any other real mode interrupt) is that it's 16-bit code, and there's no way it'll run with the processor in 32-bit mode.

There's a sys_vm86 old (113), and a sys_vm86 (166), used by dosemu, I think, that might allow you to do it. I have *no* idea how to use these - if anyone has an example, please post!

Sending ascii 7 (BELL) to stdout in the usual way (sys_write) beeps the speaker, if that'll satisfy you...

If you want a "fancier beep", I've got an example that gets permission to diddle the ports with sys_ioperm, and beeps the speaker (in a "tune", of sorts) using ports... I can post that, if anyone's interested.

Here's the "easy way"...

Best,
Frank


;--------------------------
; nasm -f elf beep.asm
; ld -s -o beep beep.o

global _start
section .text
_start:

mov eax,4  ; sys_write
mov ebx,1  ; stdout
mov ecx,beep ; buffer
mov edx, 1  ; length
int 80h

mov eax,1  ; sys_exit
xor ebx, ebx ; I didn't see an error, did you see an error? :)
int 80h

;section .data
; hell, put it in the code section...
beep db 7 ; "BELL"
;--------------------------