<!DOCTYPE html>

<html>
<head>
<meta charset="UTF-8">
<link href="style.css" type="text/css" rel="stylesheet">
<title>CMPXCHG8B/CMPXCHG16B—Compare and Exchange Bytes </title></head>
<body>
<h1>CMPXCHG8B/CMPXCHG16B—Compare and Exchange Bytes</h1>
<table>
<tr>
<th>Opcode/Instruction</th>
<th>Op/En</th>
<th>64-Bit Mode</th>
<th>Compat/Leg Mode</th>
<th>Description</th></tr>
<tr>
<td>
<p>0F C7 /<em>1 m64</em></p>
<p>CMPXCHG8B <em>m64</em></p></td>
<td>M</td>
<td>Valid</td>
<td>Valid*</td>
<td>Compare EDX:EA