Note: if you have an Intel cpu with FlexPriority, or if you are running kvm-58 or higher, you can ignore this.
Working around a slow Windows virtual machine due to ACPI
If your Windows installation is set to use ACPI (this is the default), kvm can be quite slow or not work at all. This is due to Windows heavily using a register that has a very large virtualization penalty.
Fortunately, there is a simple workaround available: disable ACPI support in Windows. The procedure for doing this is:
- Select "My Computer" with the right mouse button.
- Select "Properties".
- Choose the "Hardware" tab.
- Click the "Device Manager" button.
- Select the entry under "Computer" with the right mouse button. If it says "Standard PC", then there's no need to do anything.
- Select "Properties"
- Click the "Update Driver" button.
- Choose "No, not this time" and click "Next".
- Choose "Install from a list" and click "Next".
- Choose "Don't search" and click "Next".
- Click "Next".
- Choose "Standard PC" and click "Next".
- Continue clicking "Next" and reboot the virtual machine.
If you're installing Windows XP/2000, you can get it to use the Standard PC HAL by pressing F7 when it asks for drivers ("Press F6 for..."), there is no visual indication. If you would rather select the right HAL from a list visually then press F5 instead.
Blue Screen of Death with Standard PC HAL
On the first reboot you may encounter a BSOD with a message stating that something is wrong with intelppm.sys or processor.sys. While this message may disappear after a reboot, it is not always the case so you will have to apply the working workaround:
- Restart the virtual machine with kvm disabled (either unload the modules or run with -no-kvm)
- When windows has successfully restarted, change the value of the key Start to 4 for the following registry keys using regedit:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Processor HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Intelppm
- Reboot with kvm activated and enjoy the speed!
(source http://blogs.msdn.com/virtual_pc_guy/archive/2005/10/24/484461.aspx)