Download Sun VirtualBox User Manual - Oracle Software Downloads

1 Introduction
2. You must enable hardware virtualization for the particular VM for which you
want 64-bit support; software virtualization is not supported for 64-bit VMs.
3. If you want to use 64-bit guest support on a 32-bit host operating system, you
must also select a 64-bit operating system for the particular VM. Since supporting
64 bits on 32-bit hosts incurs additional overhead, VirtualBox only enables this
support upon explicit request.
On 64-bit hosts, 64-bit guest support is always enabled, so you can simply install
a 64-bit operating system in the guest.
Warning: On any host, you should enable the I/O APIC for virtual machines
that you intend to use in 64-bit mode. This is especially true for 64-bit Windows VMs. See chapter 3.7.1.2, “Advanced” tab, page 45. In addition, for
64-bit Windows guests, you should make sure that the VM uses the Intel networking device, since there is no 64-bit driver support for the AMD PCNet
card; see chapter 6.1, Virtual networking hardware, page 81.
If you use the “Create VM” wizard of the VirtualBox graphical user interface (see
chapter 3.2, Creating a virtual machine, page 32), VirtualBox will automatically use
the correct settings for each selected 64-bit operating system type.
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