Update firmware to prevent "VT-x is locked" error

The virtualization technologies in the Intel CPUs that Apple uses have been greatly welcomed by the Mac community, and have enabled people to run multiple operating systems side-by-side. There is a small issue that may happen with some Macs when launching virtual machines (VMWare, Parallels, or Sun's VirtualBox) where the "VT-x" support is locked and the software will not run.

This problem has surfaced periodically in the past few years, as MacOSX.com reader "bobt" writes:

"I have been having a running email conversation with the the Parallels support team over an issue with VT-x support on my Mac Intel Mini without getting any resolution. Maybe somebody else has seen my problem and knows of a solution.

When I start a Windows XP VM, I get the following message:

'Your CPU supports Intel Virtualization Technology (VT-x) but it is currently disabled (locked by firmware). Virtual machine will be started without VT-x support (in software virtualization mode).'"

This problem is generally caused by the need for a firmware update on older Macs, and Apple has a knowledgebase article outlining the problem and the firmware updates that are required to address it. Since these problems have mainly cropped up on older Mac Pros and Mac Minis, Apple provides the following links to the respective firmware updates, but recommends you use Software Update to install the latest firmware for your machine.

In some instances, this may also be caused by some virtual machine settings despite having upgraded the firmware. In Parallels, going to the "Resource Options" settings and modifying the "Acceleration Level" settings has worked for some people, with "normal" rather than "high" giving working results.

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