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<chapter id="BasicConcepts">

<title>Configuring virtual machines</title>

<para>Whereas <xref linkend="Introduction" /> gave you a quick introduction

to VirtualBox and how to get your first virtual machine running, the

following chapter describe in detail how to configure virtual

machines.</para>

<para>You have considerable latitude in deciding what virtual hardware will

be provided to the guest. The virtual hardware can be used for communicating

with the host system or with other guests. For instance, if you provide

VirtualBox with the image of a CD-ROM in an ISO file, VirtualBox can present

this image to a guest system as if it were a physical CD-ROM. Similarly, you

can give a guest system access to the real network via its virtual network

card, and, if you choose, give the host system, other guests, or computers

on the Internet access to the guest system.</para>

<sect1>

<title id="guestossupport">Supported guest operating systems</title>

<para>Since VirtualBox is designed to provide a generic virtualization

environment for x86 systems, it may run operating systems of any kind,

even those that are not officially supported by $VBOX_VENDOR. However, our

focus is to optimize the product's performance for a select list of guest

systems:</para>

<para><glosslist>

<glossentry>

<glossterm>Windows NT 4.0</glossterm>

<glossdef>

<para>All versions/editions and service packs are fully supported;

however, there are some issues with older service packs. We

recommend to install service pack 6a. Guest Additions are

available with a limited feature set.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Windows 2000 / XP / Server 2003 / Vista / Server 2008 /

Windows 7</glossterm>

<glossdef>

<para>All versions/editions and service packs are fully supported

(including 64-bit versions, under the preconditions listed below).

Guest Additions are available.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>DOS / Windows 3.x / 95 / 98 / ME</glossterm>

<glossdef>

<para>Limited testing has been performed. Use beyond legacy

installation mechanisms not recommended. No Guest Additions

available.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Linux 2.4</glossterm>

<glossdef>

<para>Limited support.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Linux 2.6</glossterm>

<glossdef>

<para>All versions/editions are fully supported (32 bits and 64

bits). Guest Additions are available.</para>

<para>We strongly recommend using a Linux kernel version 2.6.13 or

higher for better performance.<note>

<para>Certain Linux kernel releases have bugs that prevent

them from executing in a virtual environment; please see <xref

linkend="trouble-linux-buggy" /> for details.</para>

</note></para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Solaris 10, OpenSolaris</glossterm>

<glossdef>

<para>Fully supported (32 bits and 64 bits). Guest Additions are

available.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>FreeBSD</glossterm>

<glossdef>

<para>Requires hardware virtualization to be enabled. Limited

support. Guest Additions are not available yet.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>OpenBSD</glossterm>

<glossdef>

<para>Requires hardware virtualization to be enabled. Versions 3.7

and later are supported. Guest Additions are not available

yet.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>OS/2 Warp 4.5</glossterm>

<glossdef>

<para>Requires hardware virtualization to be enabled. We

officially support MCP2 only; other OS/2 versions may or may not

work. Guest Additions are available with a limited feature

set.<footnote>

<para>See <xref linkend="KnownIssues" />.</para>

</footnote></para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Mac OS X Server</glossterm>

<glossdef>

<para>VirtualBox 3.2 added experimental support for Mac OS X

Server guests, but this comes with restrictions. Please see the

following section as well as <xref

linkend="KnownIssues" />.</para>

</glossdef>

</glossentry>

</glosslist></para>

<sect2 id="intro-macosxguests">

<title>Mac OS X Server guests</title>

<para>Starting with version 3.2, VirtualBox has experimental support for

Mac OS X Server guests. This allows you to install and execute

unmodified versions of Mac OS X Server on supported host

hardware.</para>

<para>Whereas competing solutions perform modifications to the Mac OS X

Server install DVDs (e.g. different boot loader and replaced files),

VirtualBox is the first product to provide the modern PC architecture

expected by OS X without requiring any "hacks".</para>

<para>You should be aware of a number of <emphasis role="bold">important

issues</emphasis> before attempting to install a Mac OS X Server

guest:<orderedlist>

<listitem>

<para>Mac OS X is commercial, licensed software and contains both

license and technical restrictions that limit its use to certain

hardware and usage scenarios. It is important that you understand

and obey these restrictions. Only the Mac OS X Server is designed

to be used in a virtual environment and therefore, VirtualBox does

not support Mac OS X client as a guest.</para>

<para>As a result, before attempting to install Mac OS X Server in

a virtual machine, make sure you understand the <emphasis

role="bold">license restrictions</emphasis> of the Mac OS X

version you want to use. For most versions of Mac OS X Server,

Apple prohibits installing them on non-Apple hardware.</para>

<para>These license restrictions are also enforced on a technical

level: Mac OS X Server verifies whether it is running on Apple

hardware, and most DVDs that that come with Apple hardware even

check for an exact model. These restrictions are

<emphasis>not</emphasis> circumvented by VirtualBox and continue

to apply.</para>

</listitem>

<listitem>

<para>Only <emphasis role="bold">CPUs</emphasis> known and tested

by Apple are supported. As a result, if the Intel CPU is newer

than the build of Mac OS X Server, it will most likely panic

during bootup with an "Unsupported CPU" exception. It is generally

best to use the Mac OS X Server DVD that came with your Apple

hardware.</para>

</listitem>

<listitem>

<para>The Mac OS X Server installer expects the harddisk to be

<emphasis role="bold">partitioned</emphasis> so when it does not

offer a selection, you have to launch the Disk Utility from the

"Tools" menu and partition the hard disk. Then close the Disk

Utility and proceed with the installation.</para>

</listitem>

<listitem>

<para>In addition, as Mac OS X Server support in VirtualBox is

currently still experimental, please refer also to <xref

linkend="KnownIssues" />.</para>

</listitem>

</orderedlist></para>

</sect2>

<sect2 id="intro-64bitguests">

<title>64-bit guests</title>

<para>Starting with version 2.0, VirtualBox supports 64-bit guest

operating systems. Starting with version 2.1, you can even run 64-bit

guests on a 32-bit host operating system. The hardware prerequisites are

identical for both cases.</para>

<para>In particular, 64-bit guests are supported under the following

conditions:<orderedlist>

<listitem>

<para>You need a 64-bit processor with hardware virtualization

support (see <xref linkend="hwvirt" />).</para>

</listitem>

<listitem>

<para>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.</para>

</listitem>

<listitem>

<para>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.</para>

<para>On 64-bit hosts, 64-bit guest support is always enabled, so

you can simply install a 64-bit operating system in the

guest.</para>

</listitem>

</orderedlist></para>

<para><warning>

<para>On any host, you should enable the <emphasis role="bold">I/O

APIC</emphasis> for virtual machines that you intend to use in

64-bit mode. This is especially true for 64-bit Windows VMs. See

<xref linkend="settings-general-advanced" />. In addition, for

64-bit Windows guests, you should make sure that the VM uses the

<emphasis role="bold">Intel networking device</emphasis>, since

there is no 64-bit driver support for the AMD PCNet card; see <xref

linkend="nichardware" />.</para>

</warning></para>

<para>If you use the "Create VM" wizard of the VirtualBox graphical user

interface (see <xref linkend="gui-createvm" />), VirtualBox will

automatically use the correct settings for each selected 64-bit

operating system type.</para>

</sect2>

</sect1>

<sect1>

<title>Emulated hardware</title>

<para>VirtualBox virtualizes nearly all hardware of the host. Depending on

a VM's configuration, the guest will see the following virtual

hardware:<itemizedlist>

<listitem>

<para><emphasis role="bold">Input devices.</emphasis> By default,

VirtualBox emulates a standard PS/2 keyboard and mouse. These

devices are supported by almost all past and present operating

systems. In addition, VirtualBox can provide virtual USB input

devices.</para>

</listitem>

<listitem>

<para><emphasis role="bold">Graphics.</emphasis> the VirtualBox

graphics device (sometimes referred to as VGA device) is, unlike

nearly all other emulated devices, not based on any physical

counterpart. It is a simple, synthetic device which provides

compatibility with standard VGA and several extended registers used

by VESA BIOS Extensions (VBE).</para>

</listitem>

<listitem>

<para><emphasis role="bold">Storage.</emphasis> VirtualBox currently

emulates the standard ATA interface found on Intel PIIX3/PIIX4

chips, SATA (AHCI) interface, and two SCSI adapters (LSI Logic and

BusLogic); see <xref linkend="harddiskcontrollers" /> for details.

Whereas providing one of these would be enough for VirtualBox by

itself, this multitude of storage adapters is required for

compatibility with other hypervisors. Windows is particularly picky

about its boot devices, and migrating VMs between hypervisors is

very difficult or impossible if the storage controllers are

different.</para>

</listitem>

<listitem>

<para><emphasis role="bold">Networking.</emphasis> See <xref

linkend="nichardware" />.</para>

</listitem>

<listitem>

<para><emphasis role="bold">USB.</emphasis> VirtualBox emulates two

USB host controllers, EHCI and OHCI. There is a need for two host

controllers because OHCI only handles USB low- and full-speed

devices (both USB 1.x and 2.0), while EHCI only handles high-speed

devices (USB 2.0 only). The emulated USB controllers do not

communicate directly with devices on the host but rather with the

VUSB layer (see below), which abstracts the USB protocol and allows

the use of remote USB devices (with VRDP).</para>

</listitem>

<listitem>

<para><emphasis role="bold">Audio.</emphasis> Two audio devices are

emulated, an AC97 controller plus codec, and a classic SoundBlaster

16 (digital audio only).</para>

</listitem>

</itemizedlist></para>

</sect1>

<sect1 id="generalsettings">

<title>General settings</title>

<para>In the Settings window, under "General", you can configure the most

fundamental aspects of the virtual machine such as memory and essential

hardware. There are three tabs, "Basic", "Advanced" and

"Description".</para>

<sect2>

<title>"Basic" tab</title>

<para>Under the "Basic" tab of the "General" settings category, you can

find these settings:</para>

<glosslist>

<glossentry>

<glossterm>Name</glossterm>

<glossdef>

<para>The name under which the VM is shown in the list of VMs in

the main window. Under this name, VirtualBox also saves the VM's

configuration files. By changing the name, VirtualBox renames

these files as well. As a result, you can only use characters

which are allowed in your host operating system's file

names.</para>

<para>Note that internally, VirtualBox uses unique identifiers

(UUIDs) to identify virtual machines. You can display these with

<computeroutput>VBoxManage</computeroutput>.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Operating System / Version</glossterm>

<glossdef>

<para>The type of the guest operating system that is (or will be)

installed in the VM. This is the same setting that was specified

in the "New Virtual Machine" wizard, as described with <xref

linkend="gui-createvm" /> above.</para>

</glossdef>

</glossentry>

</glosslist>

</sect2>

<sect2 id="settings-general-advanced">

<title>"Advanced" tab</title>

<para><glosslist>

<glossentry>

<glossterm>Snapshot folder</glossterm>

<glossdef>

<para>By default, VirtualBox saves snapshot data together with

your other VirtualBox configuration data; see <xref

linkend="vboxconfigdata" />. With this setting, you can specify

any other folder for each VM.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Shared Clipboard</glossterm>

<glossdef>

<para>If the virtual machine has Guest Additions installed, you

can select here whether the clipboard of the guest operating

system should be shared with that of your host. If you select

"Bidirectional", then VirtualBox will always make sure that both

clipboards contain the same data. If you select "Host to guest"

or "Guest to host", then VirtualBox will only ever copy

clipboard data in one direction.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Removable Media: Remember Runtime Changes</glossterm>

<glossdef>

<para>If this is checked, VirtualBox will save the state of what

media has been mounted between several runs of a virtual

machine.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Mini Toolbar</glossterm>

<glossdef>

<para>In full screen or seamless mode, VirtualBox can display a

small toolbar that contains some of the items that are normally

available from the virtual machine's menu bar. This toolbar

reduces itself to a small gray line unless you move the mouse

over it. With the toolbar, you can return from full screen or

seamless mode, control machine execution or enable certain

devices. If you don't want to see the toolbar, disable this

setting.</para>

</glossdef>

</glossentry>

</glosslist></para>

</sect2>

<sect2>

<title>"Description" tab</title>

<para>Here you can enter any description for your virtual machine, if

you want. This has no effect of the functionality of the machine, but

you may find this space useful to note down things like the

configuration of a virtual machine and the software that has been

installed into it.</para>

</sect2>

</sect1>

<sect1 id="settings-system">

<title>System settings</title>

<para>The "System" category groups various settings that are related to

the basic hardware that is presented to the virtual machine.<note>

<para>As the activation mechanism of Microsoft Windows is sensitive to

hardware changes, if you are changing hardware settings for a Windows

guest, some of these changes may trigger a request for another

activation with Microsoft.</para>

</note></para>

<sect2 id="settings-motherboard">

<title>"Motherboard" tab</title>

<para>On the "Motherboard" tab, you can influence virtual hardware that

would normally be on the motherboard of a real computer.<glosslist>

<glossentry>

<glossterm>Base memory</glossterm>

<glossdef>

<para>This sets the amount of RAM that is allocated and given to

the VM when it is running. The specified amount of memory will

be requested from the host operating system, so it must be

available or made available as free memory on the host when

attempting to start the VM and will not be available to the host

while the VM is running. This is the same setting that was

specified in the "New Virtual Machine" wizard, as described with

guidelines under <xref linkend="gui-createvm" /> above.</para>

<para>Generally, it is possible to change the memory size after

installing the guest operating system (provided you do not

reduce the memory to an amount where the operating system would

no longer boot).</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Boot order</glossterm>

<glossdef>

<para>This setting determines the order in which the guest

operating system will attempt to boot from the various virtual

boot devices. Analogous to a real PC's BIOS setting, VirtualBox

can tell a guest OS to start from the virtual floppy, the

virtual CD/DVD drive, the virtual hard drive (each of these as

defined by the other VM settings), the network, or none of

these.</para>

<para>If you select "Network", the VM will attempt to boot from

a network via the PXE mechanism. This needs to be configured in

detail on the command line; please see <xref

linkend="vboxmanage-modifyvm" />.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Enable I/O APIC</glossterm>

<glossdef>

<para>Advanced Programmable Interrupt Controllers (APICs) are a

newer x86 hardware feature that have replaced old-style

Programmable Interrupt Controllers (PICs) in recent years. With

an I/O APIC, operating systems can use more than 16 interrupt

requests (IRQs) and therefore avoid IRQ sharing for improved

reliability.<note>

<para>Enabling the I/O APIC is <emphasis>required</emphasis>

for 64-bit guest operating systems, especially Windows

Vista; it is also required if you want to use more than one

virtual CPU in a virtual machine.</para>

</note></para>

<para>However, software support for I/O APICs has been

unreliable with some operating systems other than Windows. Also,

the use of an I/O APIC slightly increases the overhead of

virtualization and therefore slows down the guest OS a

little.<warning>

<para>All Windows operating systems starting with Windows

2000 install different kernels depending on whether an I/O

APIC is available. As with ACPI, the I/O APIC therefore

<emphasis>must not be turned off after

installation</emphasis> of a Windows guest OS. Turning it on

after installation will have no effect however.</para>

</warning></para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Enable EFI</glossterm>

<glossdef>

<para>This enables Extensible Firmware Interface (EFI), which

replaces the legacy BIOS, which may be useful for certain

advanced use cases. Please refer to <xref linkend="efi" /> for

details.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Hardware clock in UTC time</glossterm>

<glossdef>

<para>If checked, VirtualBox will report the system time in UTC

format to the guest instead of local (host) time. This affects

how the virtual real-time clock (RTC) operates and may be useful

for Unix-like guest operating systems, which typically expect

the hardware clock to be set to UTC.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Enable absolute pointing device</glossterm>

<glossdef>

<para>If enabled, VirtualBox reports to the virtual machine that

a USB tablet device is present and communicates mouse events to

the virtual machine through this device. If disabled, mouse

events are communicated through a traditional PS/2 virtual mouse

device.</para>

<para>Using the virtual USB tablet has the advantage that

movements are reported in absolute coordinates (instead of as

relative position changes), which allows VirtualBox to translate

mouse events over the VM window into tablet events without

having to "capture" the mouse in the guest as described in <xref

linkend="keyb_mouse_normal" />. This makes using the VM less

tedious even if Guest Additions are not installed.<footnote>

<para>The virtual USB tablet was added with VirtualBox 3.2.

Depending on the guest operating system selected, this is

now enabled by default for new virtual machines.</para>

</footnote></para>

</glossdef>

</glossentry>

</glosslist></para>

<para>In addition, you can turn off the <emphasis role="bold">Advanced

Configuration and Power Interface (ACPI)</emphasis> which VirtualBox

presents to the guest operating system by default. ACPI is the current

industry standard to allow operating systems to recognize hardware,

configure motherboards and other devices and manage power. As all modern

PCs contain this feature and Windows and Linux have been supporting it

for years, it is also enabled by default in VirtualBox. It can only be

turned off on the command line; see <xref

linkend="vboxmanage-modifyvm" />.<warning>

<para>All Windows operating systems starting with Windows 2000

install different kernels depending on whether ACPI is available, so

ACPI <emphasis>must not be turned off</emphasis> after installation

of a Windows guest OS. Turning it on after installation will have no

effect however.</para>

</warning></para>

</sect2>

<sect2 id="settings-processor">

<title>"Processor" tab</title>

<para>On the "Processor" tab, you can set how many virtual <emphasis

role="bold">CPU cores</emphasis> the guest operating systems should see.

Starting with version 3.0, VirtualBox supports symmetrical

multiprocessing (SMP) and can present up to 32 virtual CPU cores to each

virtual machine.</para>

<para>You should not, however, configure virtual machines to use more

CPU cores than you have available physically.</para>

<para>In addition, the <emphasis role="bold">"Enable PAE/NX"</emphasis>

setting determines whether the PAE and NX capabilities of the host CPU

will be exposed to the virtual machine. PAE stands for "Physical Address

Extension". Normally, if enabled and supported by the operating system,

then even a 32-bit x86 CPU can access more than 4 GB of RAM. This is

made possible by adding another 4 bits to memory addresses, so that with

36 bits, up to 64 GB can be addressed. Some operating systems (such as

Ubuntu Server) require PAE support from the CPU and cannot be run in a

virtual machine without it.</para>

<para>With virtual machines running modern server operating systems,

VirtualBox also supports CPU hot-plugging. For details about this,

please refer to <xref linkend="cpuhotplug" />.</para>

</sect2>

<sect2>

<title>"Acceleration" tab</title>

<para>On this page, you can determine whether and how VirtualBox should

use hardware virtualization extensions that your host CPU may support.

This is the case with most CPUs built after 2006.</para>

<para>You can select for each virtual machine individually whether

VirtualBox should use software or hardware virtualization.<footnote>

<para>Prior to VirtualBox version 2.2, software virtualization was

the default; starting with version 2.2, VirtualBox will enable

hardware virtualization by default for new virtual machines that you

create. (Existing virtual machines are not automatically changed for

compatibility reasons, and the default can of course be changed for

each virtual machine.)</para>

</footnote></para>

<para>In most cases, the default settings will be fine; VirtualBox will

have picked sensible defaults depending on the operating system that you

selected when you created the virtual machine. In certain situations,

however, you may want to change these preconfigured defaults.</para>

<para>Advanced users may be interested in technical details about

software vs. hardware virtualization; please see <xref

linkend="hwvirt" />.</para>

<para>If your host's CPU supports the <emphasis role="bold">nested

paging</emphasis> (AMD-V) or <emphasis role="bold">EPT</emphasis> (Intel

VT-x) features, then you can expect a significant performance increase

by enabling nested paging in addition to hardware virtualization. Nested

paging is still disabled by default even for new machines, but it can be

enabled for each virtual machine individually. For technical details,

see <xref linkend="nestedpaging" />.</para>

</sect2>

</sect1>

<sect1 id="settings-display">

<title>Display settings</title>

<glosslist>

<glossentry>

<glossterm>Video memory size</glossterm>

<glossdef>

<para>This sets the size of the memory provided by the virtual

graphics card available to the guest, in MB. As with the main

memory, the specified amount will be allocated from the host's

resident memory. Based on the amount of video memory, higher

resolutions and color depths may be available.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Monitor count</glossterm>

<glossdef>

<para>With this setting VirtualBox can provide more than one virtual

monitor to a virtual machine. If a guest operating system (such as

Windows) supports multiple attached monitors, VirtualBox can pretend

that multiple virtual monitors are present.<footnote>

<para>Multiple monitor support was added with VirtualBox

3.2.</para>

</footnote> Up to 8 such virtual monitors are supported.</para>

<para>The output of the multiple monitors will be displayed on the

host in multiple VM windows which are running side by side.</para>

<para>However, in fullscreen and seamless mode, they will use the

available physical monitors attached to the host. As a result, for

fullscreen and seamless modes to work with multiple monitors, you

will need at least as many physical monitors as you have virtual

monitors configured, or VirtualBox will report an error. You can

configure the relationship between guest and host monitors using the

view menu by pressing Host key + Home when you are in fullscreen or

seamless mode.</para>

<para>Please see <xref linkend="KnownIssues" /> also.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Enable 3D acceleration</glossterm>

<glossdef>

<para>If a virtual machine has Guest Additions installed, you can

select here whether the guest should support accelerated 3D

graphics. Please refer to <xref linkend="guestadd-3d" /> for

details.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Enable 2D video acceleration</glossterm>

<glossdef>

<para>If a virtual machine with Microsoft Windows has Guest

Additions installed, you can select here whether the guest should

support accelerated 2D video graphics. Please refer to <xref

linkend="guestadd-2d" /> for details.</para>

</glossdef>

</glossentry>

<glossentry>

<glossterm>Remote display</glossterm>

<glossdef>

<para>Under the "Remote display" tab, you can enable the VRDP server

that is built into VirtualBox to allow you to connect to the virtual

machine remotely. For this, you can use any standard RDP viewer,

such as <computeroutput>mstsc.exe</computeroutput> that comes with

Microsoft Windows or, on Linux systems, the standard open-source

<computeroutput>rdesktop</computeroutput> program. These features

are described in detail in <xref linkend="vrdp" />.</para>

</glossdef>

</glossentry>

</glosslist>

</sect1>

<sect1 id="settings-storage">

<title>Storage settings</title>

<para>In the VM Settings window, the "Storage" section allows you to

connect virtual hard disk, CD/DVD and floppy images and drives to your

virtual machine:<mediaobject>

<imageobject>

<imagedata align="center" fileref="images/vm-settings-harddisk.png"

width="10cm" />

</imageobject>

</mediaobject></para>

<para>In a real PC, so-called "storage controllers" connect physical disk

drives to the rest of the computer. Similarly, VirtualBox presents virtual

storage controllers to a virtual machine. Under each controller, the

virtual devices (hard disks, CD/DVD or floppy drives) are shown that are

attached to the controller.</para>

<para>If you have used the "Create VM" wizard to create a machine, you

will normally see the following devices:<itemizedlist>

<listitem>

<para>You will see an IDE controller, under which there are two

devices:<itemizedlist>

<listitem>

<para>one virtual hard disk connected to the IDE slot called

"primary master"; this is represented by the disk images that

you created with the machine;</para>

</listitem>

<listitem>

<para>one virtual CD/DVD drive connected to the "secondary

master".</para>

</listitem>

</itemizedlist></para>

</listitem>

<listitem>

<para>In addition, there is a floppy controller to which a virtual

floppy drive is attached.</para>

</listitem>

</itemizedlist></para>

<para>You can modify these media attachments freely. For example, if you

wish to copy some files from another virtual disk that you created, you

can connect that disk as a second hard disk. You could also add a second

virtual CD/DVD drive, or change where these items are attached.</para>

<para>In addition to the IDE controller, VirtualBox can also present an

SATA controller and a SCSI controller to the guest, which gives you 30 or

16 additional slots to attach devices to, respectively. This, however, may

require that you run a modern guest operating system. See <xref

linkend="harddiskcontrollers" /> for details.</para>

<para>To <emphasis role="bold">add another virtual hard disk or CD/DVD

drive,</emphasis> select the storage controller to which it should be

added (IDE, SATA or SCSI) and then click on the "add disk" button below

the tree. You can then either select "Add CD/DVD device" or "Add Hard

Disk". Alternatively, right-click on the storage controller and select a

menu item there.</para>

<para>On the right part of the window, you can then select where the

virtual disk should be connected to on the controller and which image file

to use.<itemizedlist>

<listitem>

<para>For virtual hard disks, a drop-down list appears on the right,

listing all the hard disk images that VirtualBox currently knows

about. If you click on the "Open Virtual Media Manager" icon to the

right, this will bring up a window in which you can select or create

a different hard disk image (see <xref linkend="vdis" /> for

details).</para>

</listitem>

<listitem>

<para>For virtual CD/DVD drives, there are two kinds of options in

the drop-down list.<itemizedlist>

<listitem>

<para>If you select "Empty", then VirtualBox will present a

virtual CD/DVD drive to the guest which has no media

inserted.</para>

</listitem>

<listitem>

<para>If you select "Host drive" from the list, then the

physical device of the host computer is connected to the VM,

so that the guest operating system can read from and write to

your physical device. This is, for instance, useful if you

want to install Windows from a real installation CD. In this

case, select your host drive from the drop-down list

presented.<note>

<para>If you want to write CDs or DVDs using the host

drive, you need to enable a special setting first; see

<xref linkend="storage-write-cds" />.</para>

</note></para>

</listitem>

<listitem>

<para>The other items in the list, like virtual hard disk

images, will be image files on your host. The file format here

is the ISO format. Most commonly, you will select this option

when installing an operating system from an ISO file that you

have obtained from the Internet. For example, most Linux

distributions are available in this way.</para>

</listitem>

</itemizedlist></para>

<note>

<para>The identification string of the drive provided to the guest

(which, in the guest, would be displayed by configuration tools

such as the Windows Device Manager) is always "VBOX CD-ROM",

irrespective of the current configuration of the virtual drive.

This is to prevent hardware detection from being triggered in the

guest operating system every time the configuration is

changed.</para>

</note>

</listitem>

</itemizedlist></para>

<para>Note that the floppy controller is special: you cannot add devices

other than floppy drives to it. Virtual floppy drives, like virtual CD/DVD

drives, can be connected to either a host floppy drive (if you have one)

or a disk image, which in this case must be in RAW format.</para>

<para>To <emphasis role="bold">remove a virtual disk or drive,</emphasis>

select it and click on the "remove" icon at the bottom (or right-click on

it and select the menu item).</para>

<para>Removable media (CD/DVDs and floppies) can be changed while the

guest is running. Since the "Settings" dialog is not available at that

time, you can also access these settings from the "Devices" menu of your

virtual machine window.</para>

<para>We have dedicated an entire chapter of this User Manual to virtual

storage: please see <xref linkend="storage" /> for every single detail

about storage configuration.</para>

</sect1>

<sect1>

<title>Audio settings</title>

<para>The "Audio" section in a virtual machine's Settings window

determines whether the VM will see a sound card connected, and whether the

audio output should be heard on the host system.</para>

<para>If audio is enabled for a guest, you can choose between the

emulation of an Intel AC'97 controller or a SoundBlaster 16 card. In any

case, you can select what audio driver VirtualBox will use on the

host.</para>

<para>On a Linux host, depending on your host configuration, you can also

select between the OSS, ALSA or the PulseAudio subsystem. On newer Linux

distributions (Fedora 8 and above, Ubuntu 8.04 and above) the PulseAudio

subsystem should be preferred.<note>

<para>Newer Windows versions do not ship with drivers for the virtual

audio hardware emulated by VirtualBox. This applies to Windows 7

(32-bit and 64-bit versions) as well as 64-bit Windows Vista. See

<xref linkend="win7_audio" /> for instructions how to solve this

problem.</para>

</note></para>

</sect1>

<sect1 id="settings-network">

<title>Network settings</title>

<para>The "Network" section in a virtual machine's Settings window allows

you to configure how VirtualBox presents virtual network cards to your VM,

and how they operate.</para>

<para>When you first create a virtual machine, VirtualBox by default

enables one virtual network card and selects the "Network Address

Translation" (NAT) mode for it. This way the guest can connect to the

outside world using the host's networking and the outside world can

connect to services on the guest which you choose to make visible outside

of the virtual machine. In most cases, this default setup will work fine

for you.</para>

<para>However, VirtualBox is extremely flexible in how it can virtualize

networking. It supports up to eight virtual network cards per virtual

machine, the first four of which can be configured in detail in the

graphical user interface. All eight network cards can be configured on the

command line with VBoxManage. Because of this, we have dedicated an entire

chapter of this manual to discussing networking configuration; please see

<xref linkend="networkingdetails" />.</para>

</sect1>

<sect1 id="serialports">

<title>Serial ports</title>

<para>VirtualBox fully supports virtual serial ports in a virtual machine

in an easy-to-use manner.<footnote>

<para>Serial port support was added with VirtualBox 1.5.</para>

</footnote></para>

<para>Ever since the original IBM PC, personal computers have been

equipped with one or two serial ports (also called COM ports by DOS and

Windows). While these are no longer as important as they were until a few

years ago (especially since mice are no longer connected to serial ports

these days), there are still some important uses left for them. For

example, serial ports can be used to set up a primitive network over a

null-modem cable, in case Ethernet is not available. Also, serial ports

are indispensable for system programmers needing to do kernel debugging,

since kernel debugging software usually interacts with developers over a

serial port. In other words, with virtual serial ports, system programmers

can do kernel debugging on a virtual machine instead of needing a real

computer to connect to.</para>

<para>If a virtual serial port is enabled, the guest operating system sees

it a standard 16450-type serial port. Both receiving and transmitting data

is supported. How this virtual serial port is then connected to the host

is configurable, and details depend on your host operating system.</para>

<para>You can use either the graphical user interface or the command-line

<computeroutput>VBoxManage</computeroutput> tool to set up virtual serial

ports. For the latter, please refer to <xref

linkend="vboxmanage-modifyvm" />; in that section, look for the

<computeroutput>--uart</computeroutput> and

<computeroutput>--uartmode</computeroutput> options.</para>

<para>In either case, you can configure up to two virtual serial ports

simultaneously. For each such device, you will need to

determine<orderedlist>

<listitem>

<para>what kind of serial port the virtual machine should see by

selecting an I/O base address and interrupt (IRQ). For these, we

recommend to use the traditional values<footnote>

<para>See, for example, <ulink

url="http://en.wikipedia.org/wiki/COM_(hardware_interface)">http://en.wikipedia.org/wiki/COM_(hardware_interface)</ulink>.</para>

</footnote>, which are:</para>

<para><orderedlist>

<listitem>

<para>COM1: I/O base 0x3F8, IRQ 4</para>

</listitem>

<listitem>

<para>COM2: I/O base 0x2F8, IRQ 3</para>

</listitem>

<listitem>

<para>COM3: I/O base 0x3E8, IRQ 4</para>

</listitem>

<listitem>

<para>COM4: I/O base 0x2E8, IRQ 3</para>

</listitem>

</orderedlist></para>

</listitem>

<listitem>

<para>Then, you will need to determine what this virtual port should

be connected to. For each virtual serial port, you have the

following options:</para>

<para><itemizedlist>

<listitem>

<para>You can elect to have the virtual serial port

"disconnected", which means that the guest will see it as

hardware, but it will behave as if no cable had been connected

to it.</para>

</listitem>

<listitem>

<para>You can connect the virtual serial port to a physical

serial port on your host. (On a Windows host, this will be a

name like <computeroutput>COM1</computeroutput>; on Linux or

OpenSolaris hosts, it will be a device node like

<computeroutput>/dev/ttyS0</computeroutput>). VirtualBox will

then simply redirect all data received from and sent to the

virtual serial port to the physical device.</para>

</listitem>

<listitem>

<para>You can tell VirtualBox to connect the virtual serial

port to a software pipe on the host. This depends on your host

operating system:<itemizedlist>

<listitem>

<para>On a Windows host, data will be sent and received

through a named pipe. You can use a helper program

called VMware Serial Line Gateway, available for

download at <literal> <ulink

url="http://www.l4ka.org/tools/vmwaregateway.php">http://www.l4ka.org/tools/vmwaregateway.php</ulink>

</literal>. This tool provides a fixed server mode named

pipe at

<computeroutput>\\.\pipe\vmwaredebug</computeroutput>

and connects incoming TCP connections on port 567 with

the named pipe.</para>

</listitem>

<listitem>

<para>On a Mac, Linux or OpenSolaris host, a local

domain socket is used instead. On Linux there are

various tools which can connect to a local domain socket

or create one in server mode. The most flexible tool is

<computeroutput>socat</computeroutput> and is available

as part of many distributions.</para>

</listitem>

</itemizedlist></para>

<para>In this case, you can configure whether VirtualBox

should create the named pipe (or, on non-Windows hosts, the

local domain socket) itself or whether VirtualBox should

assume that the pipe (or socket) exists already. With the

<computeroutput>VBoxManage</computeroutput> command-line

options, this is referred to as "server" or "client" mode,

respectively.</para>

</listitem>

</itemizedlist></para>

</listitem>

</orderedlist>Up to two serial ports can be configured simultaneously

per virtual machine, but you can pick any port numbers out of the above.

For example, you can configure two serial ports to be able to work with

COM2 and COM4 in the guest.</para>

</sect1>

<sect1>

<title>USB support</title>

<sect2 id="settings-usb">

<title>USB settings</title>

<para>The "USB" section in a virtual machine's Settings window allows

you to configure VirtualBox's sophisticated USB support.</para>

<para>VirtualBox can allow virtual machines to access the USB devices on

your host directly. To achieve this, VirtualBox presents the guest

operating system with a virtual USB controller. As soon as the guest

system starts using a USB device, it will appear as unavailable on the

host.<note>

<orderedlist>

<listitem>

<para>Be careful with USB devices that are currently in use on

the host! For example, if you allow your guest to connect to

your USB hard disk that is currently mounted on the host, when

the guest is activated, it will be disconnected from the host

without a proper shutdown. This may cause data loss.</para>

</listitem>

<listitem>

<para>Solaris hosts have a few known limitations regarding USB

support; please see <xref linkend="KnownIssues" />.</para>

</listitem>

</orderedlist>

</note></para>

<para>In addition to allowing a guest access to your local USB devices,

VirtualBox even allows your guests to connect to remote USB devices by

use of the VRDP protocol. For details about this, see <xref

linkend="usb-over-rdp" />.</para>

<para>In the Settings dialog, you can first configure whether USB is

available in the guest at all, and in addition also optionally enable

the USB 2.0 (EHCI) controller for the guest. If so, you can determine in

detail which devices are available. For this, you must create so-called

"filters" by specifying certain properties of the USB device.</para>

<para>Clicking on the "+" button to the right of the "USB Device

Filters" window creates a <emphasis role="bold">new filter.</emphasis>

You can give the filter a name (for referencing it later) and specify

the filter criteria. The more criteria you specify, the more precisely

devices will be selected. For instance, if you specify only a vendor ID

of 046d, all devices produced by Logitech will be available to the

guest. If you fill in all fields, on the other hand, the filter will

only apply to a particular device model from a particular vendor, and

not even to other devices of the same type with a different revision and

serial number.</para>

<para>In detail, the following criteria are available:</para>

<orderedlist>

<listitem>

<para><emphasis role="bold">Vendor and product ID.</emphasis> With

USB, each vendor of USB products carries an identification number

that is unique world-wide, the "vendor ID". Similarly, each line of

products is assigned a "product ID" number. Both numbers are

commonly written in hexadecimal (that is, they are composed of the

numbers 0-9 and the letters A-F), and a colon separates the vendor

from the product ID. For example,

<computeroutput>046d:c016</computeroutput> stands for Logitech as a

vendor, and the "M-UV69a Optical Wheel Mouse" product.</para>

<para>Alternatively, you can also specify <emphasis

role="bold">"Manufacturer"</emphasis> and <emphasis

role="bold">"Product"</emphasis> by name.</para>

<para>To list all the USB devices that are connected to your host

machine with their respective vendor and product IDs, you can use

the following command (see <xref linkend="vboxmanage" />): <screen>VBoxManage list usbhost</screen></para>

<para>On Windows, you can also see all USB devices that are attached

to your system in the Device Manager. On Linux, you can use the

<computeroutput>lsusb</computeroutput> command.</para>

</listitem>

<listitem>

<para><emphasis role="bold">Serial number.</emphasis> While vendor

and product ID are already quite specific to identify USB devices,

if you have two identical devices of the same brand and product

line, you will also need their serial numbers to filter them out

correctly.</para>

</listitem>

<listitem>

<para><emphasis role="bold">Remote.</emphasis> This setting

specifies whether the device will be local only, or remote only

(over VRDP), or either.</para>

</listitem>

</orderedlist>

<para>On a Windows host, you will need to unplug and reconnect a USB

device to use it after creating a filter for it.</para>

<para>As an example, you could create a new USB filter and specify a

vendor ID of 046d (Logitech, Inc), a manufacturer index of 1, and "not

remote". Then any USB devices on the host system produced by Logitech,

Inc with a manufacturer index of 1 will be visible to the guest

system.</para>

<para>Several filters can select a single device -- for example, a

filter which selects all Logitech devices, and one which selects a

particular webcam.</para>

<para>You can <emphasis role="bold">deactivate</emphasis> filters

without deleting them by clicking in the checkbox next to the filter

name.</para>

</sect2>

<sect2>

<title>Implementation notes for Windows and Linux hosts</title>

<para>On Windows hosts, a kernel mode device driver provides USB proxy

support. It implements both a USB monitor, which allows VirtualBox to

capture devices when they are plugged in, and a USB device driver to

claim USB devices for a particular virtual machine. As opposed to

VirtualBox versions before 1.4.0, system reboots are no longer necessary

after installing the driver. Also, you no longer need to replug devices

for VirtualBox to claim them.</para>

<para>On newer Linux hosts, VirtualBox accesses USB devices through

special files in the file system. When VirtualBox is installed, these

are made available to all users in the

<computeroutput>vboxusers</computeroutput> system group. In order to be

able to access USB from guest systems, make sure that you are a member

of this group.</para>

<para>On older Linux hosts, USB devices are accessed using the

<computeroutput>usbfs</computeroutput> file system. Therefore, the user

executing VirtualBox needs read and write permission to the USB file

system. Most distributions provide a group (e.g.

<computeroutput>usbusers</computeroutput>) which the VirtualBox user

needs to be added to. Also, VirtualBox can only proxy to virtual

machines USB devices which are not claimed by a Linux host USB driver.

The <computeroutput>Driver=</computeroutput> entry in

<computeroutput>/proc/bus/usb/devices</computeroutput> will show you

which devices are currently claimed. Please refer to <xref

linkend="usb_linux" /> also for details about

<computeroutput>usbfs</computeroutput>.</para>

</sect2>

</sect1>

<sect1>

<title>Shared folders</title>

<para>Shared folders allow you to easily exchange data between a virtual

machine and your host. This feature requires that the VirtualBox Guest

Additions be installed in a virtual machine and is described in detail in

<xref linkend="sharedfolders" />.</para>

</sect1>

<sect1 id="efi">

<title>Alternative firmware (EFI)</title>

<para>Starting with release 3.1, VirtualBox includes experimental support

for the Extensible Firmware Interface (EFI), which is a new industry

standard intended to eventually replace the legacy BIOS as the primary

interface for bootstrapping computers and certain system services

later.</para>

<para>By default, VirtualBox uses the BIOS firmware for virtual machines.

To use EFI for a given virtual machine, you can enable EFI in the

machine's "Settings" dialog (see <xref linkend="settings-motherboard" />).

Alternatively, use the <computeroutput>VBoxManage</computeroutput> command

line interface like this: <screen>VBoxManage modifyvm "VM name" --firmware efi</screen>

To switch back to using the BIOS, use: <screen>VBoxManage modifyvm "VM name" --firmware bios</screen>One

notable user of EFI is Apple's Mac OS X, but recent Linuxes (such as

Fedora 11) and Windows (starting with Vista) can be booted using EFI as

well.</para>

<para>Another possible use of EFI in VirtualBox is development and testing

of EFI applications, without booting any OS.</para>

<para>Note that the VirtualBox EFI support is experimental and will be

enhanced as EFI matures and becomes more widespread. While Mac OS X and

Linux guests are known to work fine, Windows guests are currently unable

to boot using EFI.</para>

<sect2 id="efividmode">

<title>Video modes in EFI</title>

<para>EFI provides two distinct video interfaces: GOP (Graphics Output

Protocol) and UGA (Universal Graphics Adapter). Mac OS X uses GOP, while

Linux tends to use UGA. VirtualBox provides a configuration option to

control the framebuffer size for both interfaces.</para>

<para>To control GOP, use the following

<computeroutput>VBoxManage</computeroutput> command: <screen>VBoxManage setextradata "VM name" VBoxInternal2/EfiGopMode N</screen>

Where N can be one of 0,1,2,3,4 referring to the 640x480, 800x600,

1024x768, 1280x1024, 1440x900 screen resolution respectively.</para>

<para>To change the UGA resolution: <screen>VBoxManage setextradata "VM name" VBoxInternal2/UgaHorizontalResolution 1440

VBoxManage setextradata "VM name" VBoxInternal2/UgaVerticalResolution 900</screen></para>

<para>The video mode for both GOP and UGA can only be changed when the

VM is powered off and remains persistent until changed.</para>

</sect2>

</sect1>

</chapter>