write message to screen in AT&T assembly

Question

I'm attemping to write my own bootloader and i'm having issues with writing to the screen. I've found examples using interrupts:

; ---------------------------------------------------------
; Main program
; ---------------------------------------------------------

        mov si, msg             ; Print message
        call putstr

hang:   jmp hang                ; Hang!



; ---------------------------------------------------------
; Functions and variables used by our bootstrap
; ----------------------------------------------------------

msg     db 'Hello Cyberspace!', 0

; Print a 0-terminated string on the screen
putstr:
        lodsb                   ; AL = [DS:SI]
        or al,al                ; Set zero flag if al=0
        jz .done                ; Jump to .done if zero flag is set
        mov ah,0x0E             ; Video function 0Eh
        mov bx,0x0007           ; Color
        int 0x10
        jmp putstr              ; Load characters until AL=0
.done:
        retn

however this is in Intel assembly format. When i attempt to convert to AT&T the opcodes themself are easy to flip but I cant figure out how to declare the message.

as it is I can not use the line

msg db "my string",0

as thats Intel. but if i try to convert it to a simliaraly formed AT&T code such as

msg .byte "test"

I cant assemble it. I have tried assembling with the linux "as" and "nasm"

does anyone know how i declare a string in AT&T format assembly?

Answer 1

What version of nasm are you using? On my linux box with nasm 2.03.01 your example (with 'msg db "my string", 0') assembled fine.

Also, according to the nasm doc it seems that 'db' is the correct usage.

Answer 2

Try :

msg: .asciz "test"

There is also .ascii , for without the null terminator.