it in CR4.</p>
<p>If an attempt is made to write a 1 to any reserved bit in CR8.</p>
<p>If an attempt is made to write a 1 to any reserved bit in CR3.</p>
<p>If an attempt is made to leave IA-32e mode by clearing CR4.PAE[bit 5].</p></td></tr>
<tr>
<td>#UD</td>
<td>
<p>If the LOCK prefix is used.</p>
<p>If an attempt is made to access CR1, CR5, CR6, or CR7.</p>
<p>If the REX.R prefix is used to specify a register other than CR8.</p></td></tr></table></body></html>