Modifying the Hardware Abstraction Layer (HAL) for a Windows virtual machine

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• You want to alter the number of CPUs presented to a Windows operating system.
• You have changed the number of CPUs presented to a virtual machine and now you see a blue screen with an error when trying to boot.
• Changing the HAL for the Windows virtual machine.

Resolution

When altering the number of CPUs presented to a Windows operating system, you also need to alter the HAL accordingly or you may experience performance issues.

 

For more information regarding these performance issues, see High CPU utilization of inactive Windows virtual machines.

 

Modifying the HAL requires changes within the operating system of the guest. To determine if the changes are supported on your specific version of Windows, contact Microsoft Technical Support. The following information may be helpful identifying the correct procedure at the Microsoft site.

 

To check which HAL you have installed in your virtual machine:

1. Right-click on My Computer, and choose Properties.
2. Click the Hardware tab.
3. Click the Device Manager tab.
4. Double-click the Computer icon to see which HAL is currently loaded.

The steps necessary to modify the HAL are dependent on the version of Windows you are running.

Windows XP / Windows 2003 / Windows 2008 / Windows 7

Windows XP Device Manager and Windows 2003 Device manager list limited choices for changing your HAL type when you click Update Driver.

 

Note: This is done by following the steps given above and right-clicking the current HAL.

 

For more information on Windows 2008 and Windows 7, see http://technet.microsoft.com/en-us/library/cc732060.aspx

Note: The preceding link was correct as of June 19, 2014. If you find the link is broken, provide feedback and a VMware employee will update the link.

 

Windows 2000

The preferred method to change from an ACPI HAL to a Standard HAL is to reinstall Windows 2000 as an upgrade.

 

For a list of supported operating systems, see the VMware Compatibility Guide.