The AMD No eXecute (NX) and the Intel eXecute Disable (XD) technology serve the same security purpose. They mark memory pages as data-only to prevent malicious software exploits and buffer overflow attacks.

Refer to the documentation for your guest operating system to determine whether it supports NX and XD.

In ESX/ESXi 3.0 and later, NX and XD technology is exposed by default for all guest operating systems that can use it (trading off some compatibility for security by default). Hosts that were previously compatible for VMotion in ESX Server 2.x might become incompatible after upgrading to ESX/ESXi 3.0 and later, because the NX or XD is now exposed when it was previously suppressed, but you can use per-virtual machine CPU compatibility masks to restore compatibility.