I don't understand the use of mov eax,ds:0x404004 and the NOP slide in this code I made

Question

Hi guys, I'm just practising the difference between global and local variables and how they are represented in x86 assembly. I just don't understand the use of the ds segment register and the NOP slide at the end (nop and xchg ax, ax are the same thing).

Thanks for your help!

Please provide a textual version of your code instead of a screenshot. Additionally, it would be easier to understand and explain if you included the code you wrote as well. — tmr232, Feb 06 '20 at 15:28

score 1 · Accepted Answer · answered Jan 16 '20 at 14:04

1

You can refer to this answer for the DS part.

I believe the nop and xchg are only paddings. They appear after ret, and they aren't executed as part of the function.

answered Jan 16 '20 at 14:04

macro_controller

1,858
10
28

Quite off-topic, but any clue why they would pad 6 bytes with 2x nop and 2x xchg? Rather than 3x xchg or 6x nop. – Daniel Sloof Jan 16 '20 at 20:11

I don't understand the use of mov eax,ds:0x404004 and the NOP slide in this code I made

1 Answers1