Configuring virtual machines
Whereas gave you a quick introduction
to VirtualBox and how to get your first virtual machine running, the
following chapter describes in detail how to configure virtual
machines.
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 so choose, give the host system, other guests, or
computers on the Internet access to the guest system.
Supported guest operating systems
Since VirtualBox is designed to provide a generic virtualization
environment for x86 systems, it may run operating systems of any kind,
even those not listed here. However, the focus is to optimize VirtualBox
for the following guest systems:
Windows NT 4.0
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.
Windows 2000 / XP / Server 2003 / Vista / Server 2008 /
Windows 7 / Windows 8 / Server 2012
All versions, editions and service packs are fully supported
(including 64-bit versions, under the preconditions listed below).
Guest Additions are available.
DOS / Windows 3.x / 95 / 98 / ME
Limited testing has been performed. Use beyond legacy
installation mechanisms not recommended. No Guest Additions
available.
Linux 2.4
Limited support.
Linux 2.6
All versions/editions are fully supported (32 bits and 64
bits). Guest Additions are available.
We strongly recommend using a Linux kernel version 2.6.13 or
higher for better performance.
Certain Linux kernel releases have bugs that prevent
them from executing in a virtual environment; please see for details.
Linux 3.x
All versions/editions are fully supported (32 bits and 64
bits). Guest Additions are available.
Solaris 10 (u6 and higher), Solaris 11 (including Solaris
11 Express)
Fully supported (32 bits and 64 bits). Guest Additions are
available.
FreeBSD
Requires hardware virtualization to be enabled. Limited
support. Guest Additions are not available yet.
OpenBSD
Requires hardware virtualization to be enabled. Versions 3.7
and later are supported. Guest Additions are not available
yet.
OS/2 Warp 4.5
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.
See .
Mac OS X
VirtualBox 3.2 added experimental support for Mac OS X
guests, but this comes with restrictions. Please see the following
section as well as .
Mac OS X guests
Starting with version 3.2, VirtualBox has experimental support for
Mac OS X guests. This allows you to install and execute unmodified
versions of Mac OS X on supported host hardware.
Whereas competing solutions perform modifications to the Mac OS X
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".
You should be aware of a number of important
issues before attempting to install a Mac OS X guest:
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.
In particular, for most versions of Mac OS X, Apple prohibits
installing them on non-Apple hardware.
These license restrictions are also enforced on a technical
level. Mac OS X 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 not
circumvented by VirtualBox and continue to apply.
Only CPUs known and tested
by Apple are supported. As a result, if your Intel CPU is newer
than the build of Mac OS X, or if you have a non-Intel CPU, it will
most likely panic during bootup with an "Unsupported CPU"
exception. It is generally best to use the Mac OS X DVD that came
with your Apple hardware.
The Mac OS X installer expects the harddisk to be
partitioned 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.
In addition, as Mac OS X support in VirtualBox is currently
still experimental, please refer also to .
64-bit guests
VirtualBox supports 64-bit guest operating systems, even on 32-bit
host operating systems,
64-bit guest support was added with VirtualBox 2.0; support
for 64-bit guests on 32-bit hosts was added with VirtualBox
2.1.
provided that the following conditions are
met:
You need a 64-bit processor with hardware virtualization
support (see ).
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.
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 (which typically come with hardware
virtualization support), 64-bit guest operating systems are always
supported regardless of settings, so you can simply install a
64-bit operating system in the guest.
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
. 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 .
If you use the "Create VM" wizard of the VirtualBox graphical user
interface (see ), VirtualBox will
automatically use the correct settings for each selected 64-bit
operating system type.
Emulated hardware
VirtualBox virtualizes nearly all hardware of the host. Depending on
a VM's configuration, the guest will see the following virtual
hardware:
Input devices. 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
to avoid having to capture mouse and keyboard, as described in .
Graphics. 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 the VESA BIOS Extensions (VBE).
Storage. VirtualBox currently
emulates the standard ATA interface found on Intel PIIX3/PIIX4
chips, the SATA (AHCI) interface, and two SCSI adapters (LSI Logic
and BusLogic); see 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.
Networking. See .
USB. 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 a
virtual USB layer which abstracts the USB protocol and allows the
use of remote USB devices.
Audio. See .
General settings
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".
"Basic" tab
Under the "Basic" tab of the "General" settings category, you can
find these settings:
Name
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.
Note that internally, VirtualBox uses unique identifiers
(UUIDs) to identify virtual machines. You can display these with
VBoxManage.
Operating system / version
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 in .
Whereas the default settings of a newly created VM depend on
the selected operating system type, changing the type later has no
effect on VM settings; this value is then purely informational and
decorative.
"Advanced" tab
Snapshot folder
By default, VirtualBox saves snapshot data together with
your other VirtualBox configuration data; see . With this setting, you can specify
any other folder for each VM.
Shared clipboard
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.
Clipboard sharing requires that the VirtualBox Guest
Additions be installed. As a result, this setting has no effect
otherwise; see for
details.
The shared clipboard is disabled by default. See
for an explanation. This
setting can be changed at any time using the "Shared Clipboard"
menu item in the "Devices" menu of the virtual machine.
Removable media: remember runtime changes
If this is checked, VirtualBox will save the state of what
media has been mounted between several runs of a virtual
machine.
Mini toolbar
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.
"Description" tab
Here you can enter any description for your virtual machine, if
you want. This has no effect on 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.
System settings
The "System" category groups various settings that are related to
the basic hardware that is presented to the virtual machine.
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.
"Motherboard" tab
On the "Motherboard" tab, you can influence virtual hardware that
would normally be on the motherboard of a real computer.
Base memory
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 above.
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).
Boot order
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.
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 .
Chipset
Here you can select which chipset will be presented to the
virtual machine. Before VirtualBox 4.0, PIIX3 was the only
available option here. For modern guest operating systems such
as Mac OS X, that old chipset is no longer well supported. As a
result, VirtualBox 4.0 introduced an emulation of the more
modern ICH9 chipset, which supports PCI express, three PCI
buses, PCI-to-PCI bridges and Message Signaled Interrupts
(MSI). This allows modern operating systems to address more PCI
devices and no longer requires IRQ sharing. Note that the ICH9
support is experimental and not recommended for guest operating
systems which do not require it.
Enable I/O APIC
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.
Enabling the I/O APIC is required
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.
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.
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
must not be turned off after
installation of a Windows guest OS. Turning it on
after installation will have no effect however.
Enable EFI
This enables Extensible Firmware Interface (EFI), which
replaces the legacy BIOS and may be useful for certain
advanced use cases. Please refer to for
details.
Hardware clock in UTC time
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.
Enable absolute pointing device
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.
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 . This makes using the VM less
tedious even if Guest Additions are not installed.
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.
In addition, you can turn off the Advanced
Configuration and Power Interface (ACPI) 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 .
All Windows operating systems starting with Windows 2000
install different kernels depending on whether ACPI is available, so
ACPI must not be turned off after installation
of a Windows guest OS. Turning it on after installation will have no
effect however.
"Processor" tab
On the "Processor" tab, you can set how many virtual CPU cores 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.
You should not, however, configure virtual machines to use more
CPU cores than you have available physically.
On this tab you can also set the CPU execution cap. This setting
limits the amount of time a host CPU spents to emulate a virtual CPU.
The default setting is 100% meaning that there is no limitation. A setting
of 50% implies a single virtual CPU can use up to 50% of a single host
CPU. Note that limiting the execution time of the virtual CPUs may induce
guest timing problems.
In addition, the "Enable PAE/NX"
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.
With virtual machines running modern server operating systems,
VirtualBox also supports CPU hot-plugging. For details about this,
please refer to .
"Acceleration" tab
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.
You can select for each virtual machine individually whether
VirtualBox should use software or hardware virtualization.
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.)
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.
Advanced users may be interested in technical details about
software vs. hardware virtualization; please see .
If your host's CPU supports the nested
paging (AMD-V) or EPT (Intel
VT-x) features, then you can expect a significant performance increase
by enabling nested paging in addition to hardware virtualization. For
technical details, see .
Display settings
Video memory size
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.
The GUI will show a warning if the amount of video memory
is too small to be able to switch the VM into full screen mode.
The minimum value depends on the number of virtual monitors, the
screen resolution and the color depth of the host display as well
as of the activation of 3D acceleration and
2D video acceleration. A rough estimate
is (color depth / 8) x
vertical pixels x
horizontal pixels x
number of screens = number of bytes.
Like said above, there might be extra memory required for any
activated display acceleration setting.
Monitor count
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.
Multiple monitor support was added with VirtualBox
3.2.
Up to 8 such virtual monitors are supported.
The output of the multiple monitors will be displayed on the
host in multiple VM windows which are running side by side.
However, in full screen and seamless mode, they will use the
available physical monitors attached to the host. As a result, for
full screen 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 full screen or
seamless mode.
Please see also.
Enable 3D acceleration
If a virtual machine has Guest Additions installed, you can
select here whether the guest should support accelerated 3D
graphics. Please refer to for
details.
Enable 2D video acceleration
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 for details.
Remote display
Under the "Remote display" tab, if the VirtualBox Remote
Display Extension (VRDE) is installed, you can enable the VRDP server
that is built into VirtualBox. This allows you to connect to the
console of the virtual machine remotely with any standard RDP viewer,
such as mstsc.exe that comes with
Microsoft Windows. On Linux and Solaris systems you can use the
standard open-source rdesktop
program. These features are described in detail in
.
Storage settings
The "Storage" category in the VM settings allows you to connect
virtual hard disk, CD/DVD and floppy images and drives to your virtual
machine.
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) attached to the
controller are shown.
This section can only give you a quick introduction to the
VirtualBox storage settings. Since VirtualBox gives you an enormous
wealth of options in this area, we have dedicated an entire chapter of
this User Manual to explaining all the details: please see .
If you have used the "Create VM" wizard to create a machine, you
will normally see something like the following:
Depending on the guest operating system type that you selected when
you created the VM, the typical layout of storage devices in a new VM is
as follows:
You will see an IDE
controller, to which a virtual CD/DVD drive has been
attached (to the "secondary master" port of the IDE
controller).
You will also see a SATA
controller, which is a more modern type of storage
controller for higher hard disk data throughput, to which the
virtual hard disks are attached. Initially you will normally have
one such virtual disk, but as you can see in the above screenshot,
you can have more than one, each represented by a disk image file
(VDI files, in this case).
If you created your VM with an older version of VirtualBox, the
default storage layout may differ. You might then only have an IDE
controller to which both the CD/DVD drive and the hard disks have been
attached. This might also apply if you selected an older operating system
type when you created the VM. Since older operating systems do not support
SATA without additional drivers, VirtualBox will make sure that no such
devices are present initially. Please see for additional information.
VirtualBox also provides a floppy
controller, which 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.
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, as in the above screenshot.
You could also add a second virtual CD/DVD drive, or change where these
items are attached. The following options are available:
To add another virtual hard disk, or a
CD/DVD or floppy drive, select the storage controller to
which it should be added (IDE, SATA, SCSI, SAS, floppy controller)
and then click on the "add disk" button below the tree. You can then
either select "Add CD/DVD device" or "Add Hard Disk". (If you
clicked on a floppy controller, you can add a floppy drive instead.)
Alternatively, right-click on the storage controller and select a
menu item there.
On the right part of the window, you can then set the
following:
You can then select to which device slot of the controller the
virtual disk should be connected to. IDE controllers have four
slots which have traditionally been called "primary master",
"primary slave", "secondary master" and "secondary slave". By
contrast, SATA and SCSI controllers offer you up to 30 slots
to which virtual devices can be attached.
You can select which image
file to use.
For virtual hard disks, a button with a drop-down
list appears on the right, offering you to either select
a virtual hard disk
file using a standard file dialog or to
create a new hard disk
(image file), which will bring up the "Create new disk"
wizard, which was described in .
For details on the image file types that are
supported, please see .
For virtual CD/DVD drives, the image files will
typically be in the standard ISO format instead. 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.
For virtual CD/DVD drives, the following
additional options are available:
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.
If you want to write (burn) CDs or DVDs using
the host drive, you need to also enable the
"Passthrough"
option; see .
If you select "Remove
disk from virtual drive", VirtualBox will
present an empty CD/DVD drive to the guest into
which no media has been inserted.
To remove an attachment,
select it and click on the "remove" icon at the bottom (or
right-click on it and select the menu item).
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.
Audio settings
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.
If audio is enabled for a guest, you can choose between the
emulation of an Intel AC'97 controller, an Intel HD Audio
controller
Intel HD Audio support was added with VirtualBox 4.0 because
Windows 7 (32-bit and 64-bit versions) as well as 64-bit Windows Vista
do not support the Intel AC'97 controller.
or a SoundBlaster 16 card. In any case, you can select what
audio driver VirtualBox will use on the host.
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.
Network settings
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.
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.
This default setup is good for probably 95% of VirtualBox users.
However, VirtualBox is extremely flexible in how it can virtualize
networking. It supports many virtual network cards per virtual machine,
the first four of which can be configured in detail in the Manager window.
Additional network cards can be configured on the command line with
VBoxManage.
Because of the vast array of options available, we have dedicated an
entire chapter of this manual to discussing networking configuration;
please see .
Serial ports
VirtualBox fully supports virtual serial ports in a virtual machine
in an easy-to-use manner.
Serial port support was added with VirtualBox 1.5.
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). Serial ports were commonly used with modems, and some
computer mice used to be connected to serial ports before USB became
commonplace.
While serial ports are no longer as ubiquitous as they used to be,
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.
With virtual serial ports, system programmers can do kernel debugging on a
virtual machine instead of needing a real computer to connect to.
If a virtual serial port is enabled, the guest operating system sees
a standard 16550A compatible UART device. Both receiving and transmitting
data is supported. How this virtual serial port is then connected to the
host is configurable, and the details depend on your host operating system.
You can use either the graphical user interface or the command-line
VBoxManage tool to set up virtual serial
ports. For the latter, please refer to ; in that section, look for the
--uart and
--uartmode options.
In either case, you can configure up to two virtual serial ports per
virtual machine. For each such device, you will need to
determine
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
See, for example, http://en.wikipedia.org/wiki/COM_(hardware_interface).
, which are:
COM1: I/O base 0x3F8, IRQ 4
COM2: I/O base 0x2F8, IRQ 3
COM3: I/O base 0x3E8, IRQ 4
COM4: I/O base 0x2E8, IRQ 3
Then, you will need to determine what this virtual port should
be connected to. For each virtual serial port, you have the
following options:
You can elect to have the virtual serial port
"disconnected", which means that the guest will see the
device, but it will behave as if no cable had been connected
to it.
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 COM1; on Linux or
Solaris hosts, it will be a device node like
/dev/ttyS0). VirtualBox will
then simply redirect all data received from and sent to the
virtual serial port to the physical device.
You can tell VirtualBox to connect the virtual serial
port to a software pipe on the host. This depends on your host
operating system:
On a Windows host, data will be sent and received
through a named pipe. The pipe name must be in the format
\\.\pipe\<name>
where <name> should
identify the virtual machine but may be freely
chosen.
For forwarding serial traffic, you can use a helper
program called VMware Serial Line Gateway, available for
download at
http://www.l4ka.org/91.php
. This tool provides a fixed server mode named
pipe at
\\.\pipe\vmwaredebug
and connects incoming TCP connections on port 567 with
the named pipe.
On a Mac, Linux or Solaris host, a local
domain socket is used instead. The socket filename must be
chosen such that the user running VirtualBox has
sufficient privileges to create and write to it. The
/tmp directory is often a
good candidate.
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
socat and is available
as part of many distributions.
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
VBoxManage command-line
options, this is referred to as "server" or "client" mode,
respectively.
For a direct connection between two virtual machines
(corresponding to a null-modem cable), simply configure one VM
to create a pipe/socket and another to attach to it.
You can send the virtual serial port output to a file.
This option is very useful for capturing diagnostic output from
a guest. Any file may be used for this purpose, as long as the
user running VirtualBox has sufficient privileges to create and
write to the file.
Up to two serial ports can be configured per virtual
machine, but you can pick any port numbers out of the above. However,
serial ports cannot reliably share interrupts; if both ports are to be
used at the same time, they must use different interrupt levels, for
example COM1 and COM2, but not COM1 and COM3.
USB support
USB settings
The "USB" section in a virtual machine's Settings window allows
you to configure VirtualBox's sophisticated USB support.
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.
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.
Solaris hosts have a few known limitations regarding USB
support; please see .
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 VirtualBox Remote Desktop Extension (VRDE). For details about
this, see .
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.
The EHCI controller is shipped as a VirtualBox extension
package, which must be installed separately. See for more information.
Clicking on the "+" button to the right of the "USB Device
Filters" window creates a new filter.
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.
In detail, the following criteria are available:
Vendor and product ID. 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,
046d:c016 stands for Logitech as a
vendor, and the "M-UV69a Optical Wheel Mouse" product.
Alternatively, you can also specify "Manufacturer" and "Product" by name.
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 ): VBoxManage list usbhost
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
lsusb command.
Serial number. 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.
Remote. This setting
specifies whether the device will be local only, or remote only
(over VRDP), or either.
On a Windows host, you will need to unplug and reconnect a USB
device to use it after creating a filter for it.
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.
Several filters can select a single device -- for example, a
filter which selects all Logitech devices, and one which selects a
particular webcam.
You can deactivate filters
without deleting them by clicking in the checkbox next to the filter
name.
Implementation notes for Windows and Linux hosts
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.
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
vboxusers system group. In order to be
able to access USB from guest systems, make sure that you are a member
of this group.
On older Linux hosts, USB devices are accessed using the
usbfs file system. Therefore, the user
executing VirtualBox needs read and write permission to the USB file
system. Most distributions provide a group (e.g.
usbusers) 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 Driver= entry in
/proc/bus/usb/devices will show you
which devices are currently claimed. Please refer to also for details about
usbfs.
Shared folders
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
.
Alternative firmware (EFI)
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.
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 ).
Alternatively, use the VBoxManage command
line interface like this: VBoxManage modifyvm "VM name" --firmware efi
To switch back to using the BIOS, use: VBoxManage modifyvm "VM name" --firmware biosOne
notable user of EFI is Apple's Mac OS X, but recent Linuxes (such as Fedora
11) and Windows (starting with Vista) offer special versions that can be
booted using EFI as well.
Another possible use of EFI in VirtualBox is development and testing
of EFI applications, without booting any OS.
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 with the VirtualBox EFI implementation.
Video modes in EFI
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.
To control GOP, use the following
VBoxManage command: VBoxManage setextradata "VM name" VBoxInternal2/EfiGopMode N
Where N can be one of 0,1,2,3,4 referring to the 640x480, 800x600,
1024x768, 1280x1024, 1440x900 screen resolution respectively.
To change the UGA resolution: VBoxManage setextradata "VM name" VBoxInternal2/UgaHorizontalResolution 1440
VBoxManage setextradata "VM name" VBoxInternal2/UgaVerticalResolution 900
The video mode for both GOP and UGA can only be changed when the
VM is powered off and remains persistent until changed.