source: vbox/trunk/doc/manual/en_US/user_BasicConcepts.xml@ 86692

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<chapter id="BasicConcepts">

  <title>Configuring Virtual Machines</title>

  <para>
    This chapter provides detailed steps for configuring an
    &product-name; virtual machine (VM). For an introduction to
    &product-name; and steps to get your first virtual machine running,
    see <xref linkend="Introduction" />.
  </para>

  <para>
    You have considerable latitude when deciding what virtual hardware
    to provide to the guest. Use virtual hardware to communicate with
    the host system or with other guests. For example, you can use
    virtual hardware in the following ways:
  </para>

  <itemizedlist>

    <listitem>
      <para>
        Have &product-name; present an ISO CD-ROM image to a guest
        system as if it were a physical CD-ROM.
      </para>
    </listitem>

    <listitem>
      <para>
        Provide a guest system access to the physical network through
        its virtual network card.
      </para>
    </listitem>

    <listitem>
      <para>
        Provide the host system, other guests, and computers on the
        Internet access to the guest system.
      </para>
    </listitem>

  </itemizedlist>

  <sect1 id="guestossupport">

    <title>Supported Guest Operating Systems</title>

    <para>
      Because &product-name; is designed to provide a generic
      virtualization environment for x86 systems, it can run operating
      systems (OSes) of any kind. However, &product-name; focuses on the
      following guest systems:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">Windows NT 4.0:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Fully supports all versions, editions, and service packs.
              Note that you might encounter issues with some older
              service packs, so install at least service pack 6a.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available with a limited feature set.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Windows 2000, Windows XP, Windows Server
          2003, Windows Vista, Windows Server 2008, Windows 7, Windows
          Server 2008 R2, Windows 8, Windows Server 2012, Windows 8.1,
          Windows Server 2012 R2, Windows 10 (non-Insider Preview
          releases), Windows Server 2016, Windows Server
          2019:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Fully supports all versions, editions, and service packs,
              including 64-bit versions.
            </para>
          </listitem>

          <listitem>
            <para>
              Note that you must enable hardware virtualization when
              running at least Windows 8.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">MS-DOS, Windows 3.x, Windows 95, Windows
          98, Windows ME:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Limited testing has been performed.
            </para>
          </listitem>

          <listitem>
            <para>
              Use beyond legacy installation mechanisms is not
              recommended.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are not available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Linux 2.4:</emphasis>
        </para>

        <para>
          Limited support.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Linux 2.6:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Fully supports all versions and editions, both 32-bit and
              64-bit.
            </para>
          </listitem>

          <listitem>
            <para>
              For best performance, use at least Linux kernel version
              2.6.13.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available.
            </para>
          </listitem>

        </itemizedlist>

        <note>
          <para>
            Certain Linux kernel releases have bugs that prevent them
            from executing in a virtual environment. See
            <xref linkend="ts_linux-buggy" />.
          </para>
        </note>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Linux 3.x and later:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Fully supports all versions and editions, both 32-bit and
              64-bit.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold"> Oracle Solaris 10 and Oracle Solaris
          11:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Fully supports all versions starting with Oracle Solaris
              10 8/08 and Oracle Solaris 11.
            </para>
          </listitem>

          <listitem>
            <para>
              Supports 64-bit prior to Oracle Solaris 11 11/11, and
              32-bit.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">FreeBSD:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Limited support.
            </para>
          </listitem>

          <listitem>
            <para>
              Note that you must enable hardware virtualization when
              running FreeBSD.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are not available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold"> OpenBSD:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Supports at least version 3.7.
            </para>
          </listitem>

          <listitem>
            <para>
              Note that you must enable hardware virtualization when
              running OpenBSD.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are not available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">OS/2 Warp 4.5:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              Only MCP2 is supported. Other OS/2 versions might not
              work.
            </para>
          </listitem>

          <listitem>
            <para>
              Note that you must enable hardware virtualization when
              running OS/2 Warp 4.5.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are available with a limited feature set.
              See <xref linkend="KnownIssues" />.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Mac OS X:</emphasis>
        </para>

        <itemizedlist>

          <listitem>
            <para>
              &product-name; 3.2 added experimental support for Mac OS X
              guests, with restrictions. See
              <xref linkend="intro-macosxguests"/> and
              <xref linkend="KnownIssues" />.
            </para>
          </listitem>

          <listitem>
            <para>
              Guest Additions are not available.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

    </itemizedlist>

    <sect2 id="intro-macosxguests">

      <title>Mac OS X Guests</title>

      <para>
        &product-name; enables you to install and execute unmodified
        versions of Mac OS X guests on supported host hardware. Note
        that this feature is experimental and thus unsupported.
      </para>

      <para>
        &product-name; is the first product to provide the modern PC
        architecture expected by OS X without requiring any of the
        modifications used by competing virtualization solutions. For
        example, some competing solutions perform modifications to the
        Mac OS X install DVDs, such as a different boot loader and
        replaced files.
      </para>

      <para>
        Be aware of the following important issues before you attempt to
        install a Mac OS X guest:
      </para>

      <itemizedlist>

        <listitem>
          <para>
            Mac OS X is commercial, licensed software and contains
            <emphasis role="bold">both license and technical
            restrictions</emphasis> that limit its use to certain
            hardware and usage scenarios. You must understand and comply
            with these restrictions.
          </para>

          <para>
            In particular, Apple prohibits the installation of most
            versions of Mac OS X on non-Apple hardware.
          </para>

          <para>
            These license restrictions are also enforced on a technical
            level. Mac OS X verifies that it is running on Apple
            hardware. Most DVDs that accompany Apple hardware check for
            the exact model. These restrictions are
            <emphasis>not</emphasis> circumvented by &product-name; and
            continue to apply.
          </para>
        </listitem>

        <listitem>
          <para>
            Only <emphasis role="bold">CPUs</emphasis> that are known
            and tested by Apple are supported. As a result, if your
            Intel CPU is newer than the Mac OS X build, or if you have a
            non-Intel CPU, you will likely encounter a panic during
            bootup with an "Unsupported CPU" exception.
          </para>

          <para>
            Ensure that you use the Mac OS X DVD that comes with your
            Apple hardware.
          </para>
        </listitem>

        <listitem>
          <para>
            The Mac OS X installer expects the hard disk to be
            <emphasis>partitioned</emphasis>. So, the installer will not
            offer a partition selection to you. Before you can install
            the software successfully, start the Disk Utility from the
            Tools menu and partition the hard disk. Close the Disk
            Utility and proceed with the installation.
          </para>
        </listitem>

        <listitem>
          <para>
            In addition, Mac OS X support in &product-name; is an
            experimental feature. See <xref linkend="KnownIssues" />.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

    <sect2 id="intro-64bitguests">

      <title>64-bit Guests</title>

      <warning>
        <para>
          Be sure to enable <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" />. For 64-bit
          Windows guests, ensure that the VM uses the
          <emphasis role="bold">Intel networking device</emphasis>
          because there is no 64-bit driver support for the AMD PCNet
          card. See <xref linkend="nichardware" />.
        </para>
      </warning>

      <para>
        If you use the <emphasis role="bold">Create VM</emphasis> wizard
        of the VirtualBox Manager, &product-name; automatically uses the
        correct settings for each selected 64-bit OS type. See
        <xref linkend="gui-createvm" />.
      </para>

    </sect2>

  </sect1>

  <sect1 id="basic-unattended">

    <title>Unattended Guest Installation</title>

    <para>
      &product-name; can install a guest OS automatically. You only need
      to provide the installation medium and a few other parameters,
      such as the name of the default user.
    </para>

    <para>
      Performing an unattended guest installation involves the following
      steps:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">Create a new VM.</emphasis> Use one of
          the following methods:
        </para>

        <itemizedlist>

          <listitem>
            <para>
              The VirtualBox Manager, see
              <xref linkend="gui-createvm" />.
            </para>
          </listitem>

          <listitem>
            <para>
              The <command>VBoxManage createvm</command> command, see
              <xref linkend="vboxmanage-createvm" />.
            </para>
          </listitem>

        </itemizedlist>

        <para>
          For the new VM, choose the guest OS type and accept the
          default settings for that OS. The following sections in this
          chapter describe how to change the settings for a VM.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Prepare the VM for unattended guest
          installation.</emphasis> Use the <command>VBoxManage
          unattended</command> command, see
          <xref linkend="vboxmanage-unattended" />.
        </para>

        <para>
          During this step, &product-name; scans the installation medium
          and changes certain parameters to ensure a seamless
          installation as a guest running on &product-name;.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Start the VM.</emphasis> Use the
          VirtualBox Manager or the <command>VBoxManage
          startvm</command> command.
        </para>

        <para>
          When you start the VM, the unattended installation is
          performed automatically.
        </para>

        <para>
          The installation operation changes the boot device order to
          boot the virtual hard disk first and then the virtual DVD
          drive. If the virtual hard disk is empty prior to the
          automatic installation, the VM boots from the virtual DVD
          drive and begins the installation.
        </para>

        <para>
          If the virtual hard disk contains a bootable OS, the
          installation operation exits. In this case, change the boot
          device order manually by pressing F12 during the BIOS splash
          screen.
        </para>
      </listitem>

    </itemizedlist>

    <para>
      <xref linkend="unattended-guest-install-example"/> describes how
      to perform an unattended guest installation for an Oracle Linux
      guest.
    </para>

    <sect2 id="unattended-guest-install-example">

      <title>An Example of Unattended Guest Installation</title>

      <para>
        The following example shows how to perform an unattended guest
        installation for an Oracle Linux VM. The example uses various
        <command>VBoxManage</command> commands to prepare the guest VM.
        The <command>VBoxManage unattended install</command> command is
        then used to install and configure the guest OS.
      </para>

      <orderedlist>

        <listitem>
          <para>
            Create the virtual machine.
          </para>

<screen># VM="ol7-autoinstall"
# VBoxManage list ostypes
# VBoxManage createvm --name $VM --ostype "Oracle_64" --register</screen>

          <para>
            Note the following:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                The $VM variable represents the name of the VM.
              </para>
            </listitem>

            <listitem>
              <para>
                The <command>VBoxManage list ostypes</command> command
                lists the guest OSes supported by &product-name;,
                including the name used for each OS in the
                <command>VBoxManage</command> commands.
              </para>
            </listitem>

            <listitem>
              <para>
                A 64-bit Oracle Linux 7 VM is created and registered
                with &product-name;.
              </para>
            </listitem>

            <listitem>
              <para>
                The VM has a unique UUID.
              </para>
            </listitem>

            <listitem>
              <para>
                An XML settings file is generated.
              </para>
            </listitem>

          </itemizedlist>
        </listitem>

        <listitem>
          <para>
            Create a virtual hard disk and storage devices for the VM.
          </para>

<screen># VBoxManage createhd --filename /VirtualBox/$VM/$VM.vdi --size 32768
# VBoxManage storagectl $VM --name "SATA Controller" --add sata --controller IntelAHCI
# VBoxManage storageattach $VM --storagectl "SATA Controller" --port 0 --device 0 \
--type hdd --medium /VirtualBox/$VM/$VM.vdi
# VBoxManage storagectl $VM --name "IDE Controller" --add ide
# VBoxManage storageattach $VM --storagectl "IDE Controller" --port 0 --device 0 \
--type dvddrive --medium /u01/Software/OL/OracleLinux-R7-U6-Server-x86_64-dvd.iso</screen>

          <para>
            The previous commands do the following:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                Create a 32768 MB virtual hard disk.
              </para>
            </listitem>

            <listitem>
              <para>
                Create a SATA storage controller and attach the virtual
                hard disk.
              </para>
            </listitem>

            <listitem>
              <para>
                Create an IDE storage controller for a virtual DVD drive
                and attach an Oracle Linux installation ISO.
              </para>
            </listitem>

          </itemizedlist>
        </listitem>

        <listitem>
          <para>
            (Optional) Configure some settings for the VM.
          </para>

<screen># VBoxManage modifyvm $VM --ioapic on
# VBoxManage modifyvm $VM --boot1 dvd --boot2 disk --boot3 none --boot4 none
# VBoxManage modifyvm $VM --memory 8192 --vram 128</screen>

          <para>
            The previous commands do the following:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                Enable I/O APIC for the motherboard of the VM.
              </para>
            </listitem>

            <listitem>
              <para>
                Configure the boot device order for the VM.
              </para>
            </listitem>

            <listitem>
              <para>
                Allocate 8192 MB of RAM and 128 MB of video RAM to the
                VM.
              </para>
            </listitem>

          </itemizedlist>
        </listitem>

        <listitem>
          <para>
            Perform an unattended install of the OS.
          </para>

<screen># VBoxManage unattended install $VM \
--iso=/u01/Software/OL/OracleLinux-R7-U6-Server-x86_64-dvd.iso \
--user=<replaceable>login</replaceable> --full-user-name=<replaceable>name</replaceable> --password <replaceable>password</replaceable> \
--install-additions --time-zone=CET</screen>

          <para>
            The previous command does the following:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                Specifies an Oracle Linux ISO as the installation ISO.
              </para>
            </listitem>

            <listitem>
              <para>
                Specifies a login name, full name, and login password
                for a default user on the guest OS.
              </para>

              <para>
                Note that the specified password is also used for the
                root user account on the guest.
              </para>
            </listitem>

            <listitem>
              <para>
                Installs the Guest Additions on the VM.
              </para>
            </listitem>

            <listitem>
              <para>
                Sets the time zone for the guest OS to Central European
                Time (CET).
              </para>
            </listitem>

          </itemizedlist>
        </listitem>

        <listitem>
          <para>
            Start the virtual machine.
          </para>

          <para>
            This step completes the unattended installation process.
          </para>

<screen># VBoxManage startvm $VM --type headless</screen>

          <para>
            The VM starts in headless mode, which means that the
            VirtualBox Manager window does not open.
          </para>
        </listitem>

        <listitem>
          <para>
            (Optional) Update the guest OS to use the latest Oracle
            Linux packages.
          </para>

          <para>
            On the guest VM, run the following command:
          </para>

<screen># yum update</screen>
        </listitem>

      </orderedlist>

    </sect2>

  </sect1>

  <sect1 id="emul-hardware">

    <title>Emulated Hardware</title>

    <para>
      &product-name; virtualizes nearly all hardware of the host.
      Depending on a VM's configuration, the guest will see the
      following virtual hardware:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">Input devices.</emphasis> &product-name;
          can emulate a standard PS/2 keyboard and mouse. These devices
          are supported by most guest OSes.
        </para>

        <para>
          In addition, &product-name; can provide virtual USB input
          devices to avoid having to capture mouse and keyboard, as
          described in <xref linkend="keyb_mouse_normal" />.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Graphics.</emphasis> The default
          &product-name; graphics device for Windows guests is an SVGA
          device. For Linux guests, the default graphics device emulates
          a VMware SVGA graphics device. See
          <xref linkend="settings-screen"/>.
        </para>

        <para>
          For legacy guest OSes, a VGA-compatible graphics device is
          available.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Storage.</emphasis> &product-name;
          emulates the most common types of hard disk controllers. See
          <xref linkend="harddiskcontrollers" />. Whereas supporting
          only one of these controllers would be enough for
          &product-name; by itself, this multitude of storage adapters
          is required for compatibility with other hypervisors. Windows
          is very selective 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> &product-name; emulates
          these types of USB host controllers: xHCI, EHCI, and OHCI.
          While xHCI handles all USB transfer speeds, some legacy guest
          OSes may not support xHCI. Note that for some legacy Windows
          guests, third party drivers must be installed for xHCI
          support.
        </para>

        <para>
          Legacy guest OSes typically support OHCI and EHCI. These two
          controllers are needed because OHCI only handles USB low-speed
          and full-speed devices (both USB 1.x and 2.0), while EHCI only
          handles high-speed devices (USB 2.0 only).
        </para>

        <para>
          The emulated USB controllers do not communicate directly with
          devices on the host. Instead they communicate with a virtual
          USB layer which abstracts the USB protocol and enables the use
          of remote USB devices.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Audio.</emphasis> See
          <xref linkend="settings-audio" />.
        </para>
      </listitem>

    </itemizedlist>

  </sect1>

  <sect1 id="generalsettings">

    <title>General Settings</title>

    <para>
      In the <emphasis role="bold">Settings</emphasis> window, under
      <emphasis role="bold">General</emphasis>, you can configure the
      most fundamental aspects of the virtual machine such as memory and
      essential hardware. The following tabs are available.
    </para>

    <sect2 id="settings-basic">

      <title>Basic Tab</title>

      <para>
        In the <emphasis role="bold">Basic</emphasis> tab of the
        <emphasis role="bold">General</emphasis> settings category, you
        can find these settings:
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Name:</emphasis> The name of the the
            VM, as shown in the list of VMs in the main VirtualBox
            Manager window. Using this name, &product-name; also saves
            the VM's configuration files. If you change the name,
            &product-name; renames these files as well. As a result, you
            can only use characters which are allowed for file names on
            your host OS.
          </para>

          <para>
            Note that internally, &product-name; uses unique identifiers
            (UUIDs) to identify virtual machines. You can display these
            using the <command>VBoxManage</command> commands.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Type:</emphasis> The type of the guest
            OS for the VM. This is the same setting that is specified in
            the <emphasis role="bold">New Virtual Machine</emphasis>
            wizard. See <xref linkend="gui-createvm" />.
          </para>

          <para>
            Whereas the default settings of a newly created VM depend on
            the selected OS type, changing the type later has no effect
            on VM settings. This value is purely informational and
            decorative.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Version:</emphasis> The version of the
            guest OS for the VM. This is the same setting that is
            specified in the <emphasis role="bold">New Virtual
            Machine</emphasis> wizard. See
            <xref linkend="gui-createvm" />.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

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

      <title>Advanced Tab</title>

      <para>
        The following settings are available in the
        <emphasis role="bold">Advanced</emphasis> tab:
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Snapshot Folder:</emphasis> By
            default, &product-name; saves snapshot data together with
            your other &product-name; configuration data. See
            <xref linkend="vboxconfigdata" />. With this setting, you
            can specify any other folder for each VM.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Shared Clipboard:</emphasis> You can
            select here whether the clipboard of the guest OS should be
            shared with that of your host. If you select
            <emphasis role="bold">Bidirectional</emphasis>, then
            &product-name; will always make sure that both clipboards
            contain the same data. If you select
            <emphasis role="bold">Host to Guest</emphasis> or
            <emphasis role="bold">Guest to Host</emphasis>, then
            &product-name; will only ever copy clipboard data in one
            direction.
          </para>

          <para>
            Clipboard sharing requires that the &product-name; Guest
            Additions be installed. In such a case, this setting has no
            effect. See <xref linkend="guestadditions" />.
          </para>

          <para>
            For security reasons, the shared clipboard is disabled by
            default. This setting can be changed at any time using the
            <emphasis role="bold">Shared Clipboard</emphasis> menu item
            in the <emphasis role="bold">Devices</emphasis> menu of the
            virtual machine.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Drag and Drop:</emphasis> This setting
            enables support for drag and drop. Select an object, such as
            a file, from the host or guest and directly copy or open it
            on the guest or host. Multiple drag and drop modes for a VM
            enable restricting of access in either direction.
          </para>

          <para>
            For drag and drop to work the Guest Additions need to be
            installed on the guest.
          </para>

          <note>
            <para>
              Drag and drop is disabled by default. This setting can be
              changed at any time using the <emphasis role="bold">Drag
              and Drop</emphasis> menu item in the
              <emphasis role="bold">Devices</emphasis> menu of the
              virtual machine.
            </para>
          </note>

          <para>
            See <xref linkend="guestadd-dnd"/>.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

    <sect2 id="settings-description">

      <title>Description Tab</title>

      <para>
        On the <emphasis role="bold">Description</emphasis> tab you can
        enter a description for your virtual machine. This has no effect
        on the functionality of the machine, but you may find this space
        useful to note down things such as the configuration of a
        virtual machine and the software that has been installed into
        it.
      </para>

      <para>
        To insert a line break into the
        <emphasis role="bold">Description</emphasis> text field, press
        Shift+Enter.
      </para>

    </sect2>

    <sect2 id="settings-disk-encryption">

      <title>Disk Encryption Tab</title>

      <para>
        The <emphasis role="bold">Disk Encryption</emphasis> tab enables
        you to encrypt disks that are attached to the virtual machine.
      </para>

      <para>
        To enable disk encryption, select the
        <emphasis role="bold">Enable Disk Encryption</emphasis> check
        box.
      </para>

      <para>
        Settings are available to configure the cipher used for
        encryption and the encryption password.
      </para>

      <note>
        <para>
          All files related to the virtual machine except disk images
          are stored unencrypted.
        </para>
      </note>

    </sect2>

  </sect1>

  <sect1 id="settings-system">

    <title>System Settings</title>

    <para>
      The <emphasis role="bold">System</emphasis> category groups
      various settings that are related to the basic hardware that is
      presented to the virtual machine.
    </para>

    <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>
      The following tabs are available.
    </para>

    <sect2 id="settings-motherboard">

      <title>Motherboard Tab</title>

      <para>
        On the <emphasis role="bold">Motherboard</emphasis> tab, you can
        configure virtual hardware that would normally be on the
        motherboard of a real computer.
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Base Memory:</emphasis> 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 OS, 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
            <emphasis role="bold">New Virtual Machine</emphasis> wizard,
            as described in <xref linkend="gui-createvm" />.
          </para>

          <para>
            Generally, it is possible to change the memory size after
            installing the guest OS. But you must not reduce the memory
            to an amount where the OS would no longer boot.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Boot Order:</emphasis> Determines the
            order in which the guest OS will attempt to boot from the
            various virtual boot devices. Analogous to a real PC's BIOS
            setting, &product-name; 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 <emphasis role="bold">Network</emphasis>, the
            VM will attempt to boot from a network using the PXE
            mechanism. This needs to be configured in detail on the
            command line. See <xref linkend="vboxmanage-modifyvm" />.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Chipset:</emphasis> You can select
            which chipset will be presented to the virtual machine.
            PIIX3 is the default chipset for most guests. For some guest
            OSes such as Mac OS X, the PIIX3 chipset is not well
            supported. As a result, &product-name; supports an emulation
            of the ICH9 chipset, which supports PCI express, three PCI
            buses, PCI-to-PCI bridges and Message Signaled Interrupts
            (MSI). This enables modern OSes to address more PCI devices
            and no longer requires IRQ sharing. Using the ICH9 chipset
            it is also possible to configure up to 36 network cards,
            compared to a maximum of eight network adapters with PIIX3.
            Note that ICH9 support is experimental and not recommended
            for guest OSes which do not require it.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Pointing Device:</emphasis> The
            default virtual pointing device for some guest OSes is the
            traditional PS/2 mouse. If set to <emphasis role="bold">USB
            Tablet</emphasis>, &product-name; reports to the virtual
            machine that a USB tablet device is present and communicates
            mouse events to the virtual machine through this device.
            Another setting is <emphasis role="bold">USB Multi-Touch
            Tablet</emphasis>, which is suitable for guests running
            Windows 8 or later.
          </para>

          <para>
            Using the virtual USB tablet has the advantage that
            movements are reported in absolute coordinates, instead of
            as relative position changes. This enables &product-name; 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.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable I/O APIC:</emphasis> Advanced
            Programmable Interrupt Controllers (APICs) are an x86
            hardware feature that have replaced Programmable Interrupt
            Controllers (PICs). With an I/O APIC, OSes can use more than
            16 interrupt requests (IRQs) and therefore avoid IRQ sharing
            for improved reliability.
          </para>

          <note>
            <para>
              Enabling the I/O APIC is <emphasis>required</emphasis>,
              especially for 64-bit Windows guest OSes. It is also
              required if you want to use more than one virtual CPU in a
              virtual machine.
            </para>
          </note>

          <para>
            However, software support for I/O APICs has been unreliable
            with some OSes 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.
          </para>

          <warning>
            <para>
              All Windows OSes 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>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable EFI:</emphasis> Enables
            Extensible Firmware Interface (EFI), which replaces the
            legacy BIOS and may be useful for certain advanced use
            cases. See <xref linkend="efi" />.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Hardware Clock in UTC Time:</emphasis>
            If selected, &product-name; will report the system time in
            UTC format to the guest instead of the local (host) time.
            This affects how the virtual real-time clock (RTC) operates
            and may be useful for UNIX-like guest OSes, which typically
            expect the hardware clock to be set to UTC.
          </para>
        </listitem>

      </itemizedlist>

      <para>
        In addition, you can turn off the <emphasis role="bold">Advanced
        Configuration and Power Interface (ACPI)</emphasis> which
        &product-name; presents to the guest OS by default.
      </para>

      <para>
        ACPI is the current industry standard to allow OSes to recognize
        hardware, configure motherboards and other devices and manage
        power. As most computers contain this feature and Windows and
        Linux support ACPI, it is also enabled by default in
        &product-name;. ACPI can only be turned off using the command
        line. See <xref linkend="vboxmanage-modifyvm" />.
      </para>

      <warning>
        <para>
          All Windows OSes install different kernels, depending on
          whether ACPI is available. This means that ACPI <emphasis>must
          not be turned off</emphasis> after installation of a Windows
          guest OS. However, turning it on after installation will have
          no effect.
        </para>
      </warning>

    </sect2>

    <sect2 id="settings-processor">

      <title>Processor Tab</title>

      <para>
        On the <emphasis role="bold">Processor</emphasis> tab, you can
        configure settings for the CPU used by the virtual machine.
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Processor(s):</emphasis> Sets the
            number of virtual CPU cores the guest OSes can see.
            &product-name; supports symmetrical multiprocessing (SMP)
            and can present up to 32 virtual CPU cores to each virtual
            machine.
          </para>

          <para>
            You should not configure virtual machines to use more CPU
            cores than are available physically. This includes real
            cores, with no hyperthreads.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Execution Cap:</emphasis> Configures
            the CPU execution cap. This limits the amount of time a host
            CPU spends 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 cause guest timing problems.
          </para>

          <para>
            A warning is displayed at the bottom of the Processor tab if
            an Execution Cap setting is made that may affect system
            performance.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable PAE/NX:</emphasis> Determines
            whether the PAE and NX capabilities of the host CPU will be
            exposed to the virtual machine.
          </para>

          <para>
            PAE stands for Physical Address Extension. Normally, if
            enabled and supported by the OS, 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 OSes, such as
            Ubuntu Server, require PAE support from the CPU and cannot
            be run in a virtual machine without it.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable Nested VT-x/AMD-V</emphasis>:
            Enables nested virtualization, with passthrough of hardware
            virtualization functions to the guest VM.
          </para>
        </listitem>

      </itemizedlist>

      <para>
        With virtual machines running modern server OSes, &product-name;
        also supports CPU hot-plugging. For details, see
        <xref linkend="cpuhotplug" />.
      </para>

    </sect2>

    <sect2 id="settings-acceleration">

      <title>Acceleration Tab</title>

      <para>
        On this tab, you can configure &product-name; to use hardware
        virtualization extensions that your host CPU supports.
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Paravirtualization
            Interface:</emphasis> &product-name; provides
            paravirtualization interfaces to improve time-keeping
            accuracy and performance of guest OSes. The options
            available are documented under the
            <option>--paravirtprovider</option> option in
            <xref linkend="vboxmanage-modifyvm" />. For further details
            on the paravirtualization providers, see
            <xref linkend="gimproviders" />.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Hardware Virtualization:</emphasis>
            You can configure hardware virtualization features for each
            virtual machine.
          </para>

          <itemizedlist>

            <listitem>
              <para>
                <emphasis role="bold">Enable Nested Paging:</emphasis>
                If the host 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 <xref linkend="nestedpaging" />.
                For Intel EPT security recommendations, see
                <xref linkend="sec-rec-cve-2018-3646" />.
              </para>
            </listitem>

          </itemizedlist>

          <para>
            Advanced users may be interested in technical details about
            hardware virtualization. See <xref linkend="hwvirt" />.
          </para>
        </listitem>

      </itemizedlist>

      <para>
        In most cases, the default settings on the
        <emphasis role="bold">Acceleration</emphasis> tab will work
        well. &product-name; selects sensible defaults, depending on the
        OS that you selected when you created the virtual machine. In
        certain situations, however, you may want to change the
        preconfigured defaults.
      </para>

    </sect2>

  </sect1>

  <sect1 id="settings-display">

    <title>Display Settings</title>

    <para>
      The following tabs are available for configuring the display for a
      virtual machine.
    </para>

    <sect2 id="settings-screen">

      <title>Screen Tab</title>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Video Memory:</emphasis> 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>

          <para>
            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 on the use of <emphasis>3D
            acceleration</emphasis> and <emphasis>2D video
            acceleration</emphasis>. A rough estimate is
            (<emphasis>color depth</emphasis> / 8) x <emphasis>vertical
            pixels</emphasis> x <emphasis>horizontal pixels</emphasis> x
            <emphasis>number of screens</emphasis> = <emphasis>number of
            bytes</emphasis>. Extra memory may be required if display
            acceleration is used.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Monitor Count:</emphasis> With this
            setting, &product-name; can provide more than one virtual
            monitor to a virtual machine. If a guest OS supports
            multiple attached monitors, &product-name; can pretend that
            multiple virtual monitors are present. Up to eight such
            virtual monitors are supported.
          </para>

          <para>
            The output of the multiple monitors are displayed on the
            host in multiple VM windows which are running side by side.
            However, in full screen and seamless mode, they 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
            &product-name; will report an error.
          </para>

          <para>
            You can configure the relationship between guest and host
            monitors using the <emphasis role="bold">View</emphasis>
            menu by pressing Host key + Home when you are in full screen
            or seamless mode.
          </para>

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

        <listitem>
          <para>
            <emphasis role="bold">Scale Factor:</emphasis> Enables
            scaling of the display size. For multiple monitor displays,
            you can set the scale factor for individual monitors, or
            globally for all of the monitors. Use the slider to select a
            scaling factor up to 200%.
          </para>

          <para>
            You can set a default scale factor for all VMs. Use the
            <emphasis role="bold">Display</emphasis> tab in the Global
            Settings dialogs.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Graphics Controller:</emphasis>
            Specifies the graphics adapter type used by the guest VM.
            Note that you must install the Guest Additions on the guest
            VM to specify the VBoxSVGA or VMSVGA graphics controller.
            The following options are available:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                <emphasis role="bold">VBoxSVGA:</emphasis> The default
                graphics controller for new VMs that use Windows 7 or
                later.
              </para>

              <para>
                This graphics controller improves performance and 3D
                support when compared to the legacy VBoxVGA option.
              </para>
            </listitem>

            <listitem>
              <para>
                <emphasis role="bold">VBoxVGA:</emphasis> Use this
                graphics controller for legacy guest OSes. This is the
                default graphics controller for Windows versions before
                Windows 7 and for Oracle Solaris.
              </para>

              <para>
                3D acceleration is not supported for this graphics
                controller.
              </para>
            </listitem>

            <listitem>
              <para>
                <emphasis role="bold">VMSVGA:</emphasis> Use this
                graphics controller to emulate a VMware SVGA graphics
                device. This is the default graphics controller for
                Linux guests.
              </para>
            </listitem>

            <listitem>
              <para>
                <emphasis role="bold">None:</emphasis> Does not emulate
                a graphics adapter type.
              </para>
            </listitem>

          </itemizedlist>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable 3D Acceleration:</emphasis> If
            a virtual machine has Guest Additions installed, you can
            select here whether the guest should support accelerated 3D
            graphics. See <xref linkend="guestadd-3d" />.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Enable 2D Video
            Acceleration:</emphasis> If a virtual machine with Microsoft
            Windows has Guest Additions installed, you can select here
            whether the guest should support accelerated 2D video
            graphics. See <xref linkend="guestadd-2d" />.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

    <sect2 id="settings-remote-display">

      <title>Remote Display Tab</title>

      <para>
        On the <emphasis role="bold">Remote Display</emphasis> tab, if
        the VirtualBox Remote Display Extension (VRDE) is installed, you
        can enable the VRDP server that is built into &product-name;.
        This enables you to connect to the console of the virtual
        machine remotely with any standard RDP viewer, such as
        <command>mstsc.exe</command> that comes with Microsoft Windows.
        On Linux and Oracle Solaris systems you can use the standard
        open source <command>rdesktop</command> program. These features
        are described in <xref linkend="vrde" />.
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Enable Server:</emphasis> Select this
            check box and configure settings for the remote display
            connection.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

    <sect2 id="settings-capture">

      <title>Recording Tab</title>

      <para>
        On the <emphasis role="bold">Recording</emphasis> tab you can
        enable video and audio recording for a virtual machine and
        change related settings. Note that these features can be enabled
        and disabled while a VM is running.
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">Enable Recording:</emphasis> Select
            this check box and select a <emphasis role="bold">Recording
            Mode</emphasis> option.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Recording Mode:</emphasis> You can
            choose to record video, audio, or both video and audio.
          </para>

          <para>
            Some settings on the
            <emphasis role="bold">Recording</emphasis> tab may be grayed
            out, depending on the <emphasis role="bold">Recording
            Mode</emphasis> setting.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">File Path:</emphasis> The file where
            the recording is saved.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Frame Size:</emphasis> The video
            resolution of the recorded video, in pixels. The drop-down
            list enables you to select from common frame sizes.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Frame Rate:</emphasis> Use the slider
            to set the maximum number of video frames per second (FPS)
            to record. Frames that have a higher frequency are skipped.
            Increasing this value reduces the number of skipped frames
            and increases the file size.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Video Quality:</emphasis> Use the
            slider to set the the bit rate of the video in kilobits per
            second. Increasing this value improves the appearance of the
            video at the cost of an increased file size.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Audio Quality:</emphasis> Use the
            slider to set the quality of the audio recording. Increasing
            this value improves the audio quality at the cost of an
            increased file size.
          </para>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">Screens:</emphasis> For a multiple
            monitor display, you can select which screens to record
            video from.
          </para>
        </listitem>

      </itemizedlist>

      <para>
        As you adjust the video and audio recording settings, the
        approximate output file size for a five minute video is shown.
      </para>

    </sect2>

  </sect1>

  <sect1 id="settings-storage">

    <title>Storage Settings</title>

    <para>
      The <emphasis role="bold">Storage</emphasis> category in the VM
      settings enables you to connect virtual hard disk, CD/DVD, and
      floppy images and drives to your virtual machine.
    </para>

    <para>
      In a real computer, so-called <emphasis>storage
      controllers</emphasis> connect physical disk drives to the rest of
      the computer. Similarly, &product-name; presents virtual storage
      controllers to a virtual machine. Under each controller, the
      virtual devices, such as hard disks, CD/DVD or floppy drives,
      attached to the controller are shown.
    </para>

    <note>
      <para>
        This section gives a quick introduction to the &product-name;
        storage settings. See <xref linkend="storage" /> for a full
        description of the available storage settings in &product-name;.
      </para>
    </note>

    <para>
      If you have used the <emphasis role="bold">Create VM</emphasis>
      wizard to create a machine, you will normally see something like
      the following:
    </para>

    <figure id="fig-storage-settings">
      <title>Storage Settings for a Virtual Machine</title>
     <mediaobject>
        <imageobject>
          <imagedata align="center" fileref="images/vm-settings-harddisk.png"
                     width="10cm" />
        </imageobject>
      </mediaobject>
      </figure>

    <para>
      Depending on the guest OS type that you selected when you created
      the VM, a new VM includes the following storage devices:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">IDE controller.</emphasis> A virtual
          CD/DVD drive is attached to the secondary master port of the
          IDE controller.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">SATA controller.</emphasis> This is a
          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
          shown in the previous screenshot, you can have more than one.
          Each is represented by a disk image file, such as a VDI file
          in this example.
        </para>
      </listitem>

    </itemizedlist>

    <para>
      If you created your VM with an older version of &product-name;,
      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
      OS type when you created the VM. Since older OSes do not support
      SATA without additional drivers, &product-name; will make sure
      that no such devices are present initially. See
      <xref linkend="harddiskcontrollers" />.
    </para>

    <para>
      &product-name; also provides a <emphasis>floppy
      controller</emphasis>. You cannot add devices other than floppy
      drives to this controller. 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>
      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:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          To <emphasis role="bold">add another virtual hard disk, or a
          CD/DVD or floppy drive</emphasis>, select the storage
          controller to which it should be added (such as IDE, SATA,
          SCSI, SAS, floppy controller) and then click the
          <emphasis role="bold">Add Disk</emphasis> button below the
          tree. You can then either select <emphasis role="bold">Optical
          Drive</emphasis> or <emphasis role="bold">Hard
          Disk</emphasis>. 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.
        </para>

        <para>
          A dialog is displayed, enabling you to select an existing disk
          image file or to create a new disk image file. Depending on
          the type of disk image, the dialog is called
          <emphasis role="bold">Hard Disk Selector</emphasis>,
          <emphasis role="bold">Optical Disk Selector</emphasis>, or
          <emphasis role="bold">Floppy Disk Selector</emphasis>.
        </para>

        <para>
          See <xref linkend="vdidetails"/> for information on the image
          file types that are supported by &product-name;.
        </para>

        <para>
          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 OS from an ISO file that
          you have obtained from the Internet. For example, most Linux
          distributions are available in this way.
        </para>

        <para>
          Depending on the type of disk image, you can set the following
          <emphasis role="bold">Attributes</emphasis> for the disk image
          in the right part of the Storage settings page:
        </para>

        <itemizedlist>

          <listitem>
            <para>
              The <emphasis role="bold">device slot</emphasis> of the
              controller that the virtual disk is 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 for attaching virtual
              devices.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">Solid-state Drive</emphasis>
              presents a virtual disk to the guest as a solid-state
              device.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">Hot-pluggable</emphasis> presents a
              virtual disk to the guest as a hot-pluggable device.
            </para>
          </listitem>

          <listitem>
            <para>
              For virtual CD/DVD drives, you can select
              <emphasis role="bold">Live CD/DVD</emphasis>. This means
              that the virtual optical disk is not removed from when the
              guest system ejects it.
            </para>
          </listitem>

        </itemizedlist>
      </listitem>

      <listitem>
        <para>
          To <emphasis role="bold">remove an attachment</emphasis>,
          either select it and click on the
          <emphasis role="bold">Remove</emphasis> icon at the bottom, or
          right-click on it and select the menu item.
        </para>
      </listitem>

    </itemizedlist>

    <para>
      Removable media, such as CD/DVDs and floppies, can be changed
      while the guest is running. Since the
      <emphasis role="bold">Settings</emphasis> dialog is not available
      at that time, you can also access these settings from the
      <emphasis role="bold">Devices</emphasis> menu of your virtual
      machine window.
    </para>

  </sect1>

  <sect1 id="settings-audio">

    <title>Audio Settings</title>

    <para>
      The <emphasis role="bold">Audio</emphasis> section in a virtual
      machine's <emphasis role="bold">Settings</emphasis> window
      determines whether the VM will detect a connected sound card, and
      if the audio output should be played on the host system.
    </para>

    <para>
      To enable audio for a guest, select the
      <emphasis role="bold">Enable Audio</emphasis> check box. The
      following settings are available:
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">Host Audio Driver:</emphasis> The audio
          driver that &product-name; uses on the host. On a Linux host,
          depending on your host configuration, you can select between
          the OSS, ALSA, or the PulseAudio subsystem. On newer Linux
          distributions, the PulseAudio subsystem is preferred.
        </para>

        <para>
          Only OSS is supported on Oracle Solaris hosts. The Oracle
          Solaris Audio audio backend is no longer supported on Oracle
          Solaris hosts.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Audio Controller:</emphasis> You can
          choose between the emulation of an Intel AC'97 controller, an
          Intel HD Audio controller, or a SoundBlaster 16 card.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Enable Audio Output:</emphasis> Enables
          audio output only for the VM.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Enable Audio Input:</emphasis> Enables
          audio input only for the VM.
        </para>
      </listitem>

    </itemizedlist>

  </sect1>

  <sect1 id="settings-network">

    <title>Network Settings</title>

    <para>
      The <emphasis role="bold">Network</emphasis> section in a virtual
      machine's <emphasis role="bold">Settings</emphasis> window enables
      you to configure how &product-name; presents virtual network cards
      to your VM, and how they operate.
    </para>

    <para>
      When you first create a virtual machine, &product-name; 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.
    </para>

    <para>
      This default setup is good for the majority of &product-name;
      users. However, &product-name; is extremely flexible in how it can
      virtualize networking. It supports many virtual network cards per
      virtual machine. The first four virtual network cards can be
      configured in detail in the VirtualBox Manager window. Additional
      network cards can be configured using the
      <command>VBoxManage</command> command.
    </para>

    <para>
      Many networking options are available. See
      <xref linkend="networkingdetails" /> for more information.
    </para>

  </sect1>

  <sect1 id="serialports">

    <title>Serial Ports</title>

    <para>
      &product-name; supports the use of virtual serial ports in a
      virtual machine.
    </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. Serial ports were commonly used with modems, and
      some computer mice used to be connected to serial ports before USB
      became commonplace.
    </para>

    <para>
      While serial ports are no longer as common 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.
    </para>

    <para>
      If a virtual serial port is enabled, the guest OS sees a standard
      16550A compatible UART device. Other UART types can be configured
      using the <command>VBoxManage modifyvm</command> command. 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 OS.
    </para>

    <para>
      You can use either the Settings tabs or the
      <command>VBoxManage</command> command to set up virtual serial
      ports. For the latter, see <xref linkend="vboxmanage-modifyvm" />
      for information on the <option>--uart</option>,
      <option>--uartmode</option> and <option>--uarttype</option>
      options.
    </para>

    <para>
      You can configure up to four virtual serial ports per virtual
      machine. For each device, you must set the following:
    </para>

    <orderedlist>

      <listitem>
        <para>
          <emphasis role="bold">Port Number:</emphasis> This determines
          the serial port that the virtual machine should see. For best
          results, use the traditional values as follows:
        </para>

        <itemizedlist>

          <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>

        </itemizedlist>

        <para>
          You can also configure a user-defined serial port. Enter an
          I/O base address and interrupt (IRQ).
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Port Mode:</emphasis> What the virtual
          port is connected to. For each virtual serial port, you have
          the following options:
        </para>

        <itemizedlist>

          <listitem>
            <para>
              <emphasis role="bold">Disconnected:</emphasis> The guest
              will see the device, but it will behave as if no cable had
              been connected to it.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">Host Device:</emphasis> Connects the
              virtual serial port to a physical serial port on your
              host. On a Windows host, this will be a name like
              <literal>COM1</literal>. On Linux or Oracle Solaris hosts,
              it will be a device node like
              <filename>/dev/ttyS0</filename>. &product-name; will then
              simply redirect all data received from and sent to the
              virtual serial port to the physical device.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">Host Pipe:</emphasis> Configure
              &product-name; to connect the virtual serial port to a
              software pipe on the host. This depends on your host OS,
              as follows:
            </para>

            <itemizedlist>

              <listitem>
                <para>
                  On a Windows host, data will be sent and received
                  through a named pipe. The pipe name must be in the
                  format
                  <filename>\\.\pipe\<replaceable>name</replaceable></filename>
                  where <replaceable>name</replaceable> should identify
                  the virtual machine but may be freely chosen.
                </para>
              </listitem>

              <listitem>
                <para>
                  On a Mac OS, Linux, or Oracle Solaris host, a local
                  domain socket is used instead. The socket filename
                  must be chosen such that the user running
                  &product-name; has sufficient privileges to create and
                  write to it. The <filename>/tmp</filename> directory
                  is often a good candidate.
                </para>

                <para>
                  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 <command>socat</command> and
                  is available as part of many distributions.
                </para>
              </listitem>

            </itemizedlist>

            <para>
              In this case, you can configure whether &product-name;
              should create the named pipe, or the local domain socket
              non-Windows hosts, itself or whether &product-name; should
              assume that the pipe or socket exists already. With the
              <command>VBoxManage</command> command-line options, this
              is referred to as server mode or client mode,
              respectively.
            </para>

            <para>
              For a direct connection between two virtual machines,
              corresponding to a null-modem cable, simply configure one
              VM to create a pipe or socket and another to attach to it.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">Raw File:</emphasis> 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 &product-name; has sufficient privileges to create
              and write to the file.
            </para>
          </listitem>

          <listitem>
            <para>
              <emphasis role="bold">TCP Socket:</emphasis> Useful for
              forwarding serial traffic over TCP/IP, acting as a server,
              or it can act as a TCP client connecting to other servers.
              This option enables a remote machine to directly connect
              to the guest's serial port using TCP.
            </para>

            <itemizedlist>

              <listitem>
                <para>
                  <emphasis role="bold">TCP Server:</emphasis> Deselect
                  the <emphasis role="bold">Connect to Existing
                  Pipe/Socket</emphasis> check box and specify the port
                  number in the
                  <emphasis role="bold">Path/Address</emphasis> field.
                  This is typically 23 or 2023. Note that on UNIX-like
                  systems you will have to use a port a number greater
                  than 1024 for regular users.
                </para>

                <para>
                  The client can use software such as
                  <command>PuTTY</command> or the
                  <command>telnet</command> command line tool to access
                  the TCP Server.
                </para>
              </listitem>

              <listitem>
                <para>
                  <emphasis role="bold">TCP Client:</emphasis> To create
                  a virtual null-modem cable over the Internet or LAN,
                  the other side can connect using TCP by specifying
                  <literal><replaceable>hostname</replaceable>:<replaceable>port</replaceable></literal>
                  in the <emphasis role="bold">Path/Address</emphasis>
                  field. The TCP socket will act in client mode if you
                  select the <emphasis role="bold">Connect to Existing
                  Pipe/Socket</emphasis> check box.
                </para>
              </listitem>

            </itemizedlist>
          </listitem>

        </itemizedlist>
      </listitem>

    </orderedlist>

    <para>
      Up to four 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.
    </para>

  </sect1>

  <sect1 id="usb-support">

    <title>USB Support</title>

    <sect2 id="settings-usb">

      <title>USB Settings</title>

      <para>
        The <emphasis role="bold">USB</emphasis> section in a virtual
        machine's <emphasis role="bold">Settings</emphasis> window
        enables you to configure &product-name;'s sophisticated USB
        support.
      </para>

      <para>
        &product-name; can enable virtual machines to access the USB
        devices on your host directly. To achieve this, &product-name;
        presents the guest OS with a virtual USB controller. As soon as
        the guest system starts using a USB device, it will appear as
        unavailable on the host.
      </para>

      <note>
        <itemizedlist>

          <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>
              Oracle Solaris hosts have a few known limitations
              regarding USB support. See <xref linkend="KnownIssues" />.
            </para>
          </listitem>

        </itemizedlist>
      </note>

      <para>
        In addition to allowing a guest access to your local USB
        devices, &product-name; even enables your guests to connect to
        remote USB devices by use of the VirtualBox Remote Desktop
        Extension (VRDE). See <xref linkend="usb-over-rdp" />.
      </para>

      <para>
        To enable USB for a VM, select the <emphasis role="bold">Enable
        USB Controller</emphasis> check box. The following settings are
        available:
      </para>

      <itemizedlist>

        <listitem>
          <para>
            <emphasis role="bold">USB Controller:</emphasis> Selects a
            controller with the specified level of USB support, as
            follows:
          </para>

          <itemizedlist>

            <listitem>
              <para>
                OHCI for USB 1.1
              </para>
            </listitem>

            <listitem>
              <para>
                EHCI for USB 2.0. This also enables OHCI.
              </para>
            </listitem>

            <listitem>
              <para>
                xHCI for USB 3.0. This supports all USB speeds.
              </para>
            </listitem>

          </itemizedlist>

          <note>
            <para>
              The xHCI and EHCI controllers are shipped as an
              &product-name; extension package, which must be installed
              separately. See <xref linkend="intro-installing" />.
            </para>
          </note>
        </listitem>

        <listitem>
          <para>
            <emphasis role="bold">USB Device Filters:</emphasis> When
            USB support is enabled for a VM, you can determine in detail
            which devices will be automatically attached to the guest.
            For this, you can create filters by specifying certain
            properties of the USB device. USB devices with a matching
            filter will be automatically passed to the guest once they
            are attached to the host. USB devices without a matching
            filter can be passed manually to the guest, for example by
            using the <emphasis role="bold">Devices</emphasis>,
            <emphasis role="bold">USB</emphasis> menu.
          </para>

          <para>
            Clicking on the <emphasis role="bold">+</emphasis> button to
            the right of the <emphasis role="bold">USB Device
            Filters</emphasis> window creates a new filter. You can give
            the filter a name, for later reference, 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>

          <itemizedlist>

            <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, called
                the <emphasis>vendor ID</emphasis>. Similarly, each line
                of products is assigned a <emphasis>product
                ID</emphasis> number. Both numbers are commonly written
                in hexadecimal, and a colon separates the vendor from
                the product ID. For example,
                <literal>046d:c016</literal> 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 IDs and
                product IDs, use the following command:
              </para>

<screen>VBoxManage list usbhost</screen>

              <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 <command>lsusb</command> command.
              </para>
            </listitem>

            <listitem>
              <para>
                <emphasis role="bold">Serial Number.</emphasis> While
                vendor ID and product ID are 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, remote
                only, such as over VRDP, or either.
              </para>
            </listitem>

          </itemizedlist>

          <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 for 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 deactivate filters without deleting them by
            deselecting the check box next to the filter name.
          </para>
        </listitem>

      </itemizedlist>

    </sect2>

    <sect2 id="usb-implementation-notes">

      <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 enables
        &product-name; to capture devices when they are plugged in, and
        a USB device driver to claim USB devices for a particular
        virtual machine. System reboots are not necessary after
        installing the driver. Also, you do not need to replug devices
        for &product-name; to claim them.
      </para>

      <para>
        On supported Linux hosts, &product-name; accesses USB devices
        through special files in the file system. When &product-name; is
        installed, these are made available to all users in the
        <literal>vboxusers</literal> system group. In order to be able
        to access USB from guest systems, make sure that you are a
        member of this group.
      </para>

    </sect2>

  </sect1>

  <sect1 id="shared-folders">

    <title>Shared Folders</title>

    <para>
      Shared folders enable you to easily exchange data between a
      virtual machine and your host. This feature requires that the
      &product-name; Guest Additions be installed in a virtual machine
      and is described in detail in <xref linkend="sharedfolders" />.
    </para>

  </sect1>

  <sect1 id="user-interface">

    <title>User Interface</title>

    <para>
      The <emphasis role="bold">User Interface</emphasis> section
      enables you to change certain aspects of the user interface of
      this VM.
    </para>

    <itemizedlist>

      <listitem>
        <para>
          <emphasis role="bold">Menu Bar:</emphasis> This widget enables
          you to disable menus by clicking on the menu to release it,
          menu entries by deselecting the check box of the entry to
          disable it and the complete menu bar by deselecting the
          rightmost check box.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Mini ToolBar:</emphasis> In full screen
          or seamless mode, &product-name; 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 do not want to see the toolbar, disable this setting.
        </para>

        <para>
          The second setting enables you to show the toolbar at the top
          of the screen, instead of showing it at the bottom.
        </para>
      </listitem>

      <listitem>
        <para>
          <emphasis role="bold">Status Bar:</emphasis> This widget
          enables you to disable icons on the status bar by deselecting
          the check box of an icon to disable it, to rearrange icons by
          dragging and dropping the icon, and to disable the complete
          status bar by deselecting the leftmost check box.
        </para>
      </listitem>

    </itemizedlist>

  </sect1>

  <sect1 id="efi">

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

    <para>
      &product-name; includes experimental support for the Extensible
      Firmware Interface (EFI), which is an industry standard intended
      to replace the legacy BIOS as the primary interface for
      bootstrapping computers and certain system services later.
    </para>

    <para>
      By default, &product-name; uses the BIOS firmware for virtual
      machines. To use EFI for a given virtual machine, you can enable
      EFI in the machine's <emphasis role="bold">Settings</emphasis>
      dialog. See <xref linkend="settings-motherboard"/>. Alternatively,
      use the <command>VBoxManage</command> command line interface as
      follows:
    </para>

<screen>VBoxManage modifyvm "VM name" --firmware efi</screen>

    <para>
      To switch back to using the BIOS:
    </para>

<screen>VBoxManage modifyvm "VM name" --firmware bios</screen>

    <para>
      One notable user of EFI is Apple Mac OS X. More recent Linux
      versions and Windows releases, starting with Vista, also offer
      special versions that can be booted using EFI.
    </para>

    <para>
      Another possible use of EFI in &product-name; is development and
      testing of EFI applications, without booting any OS.
    </para>

    <para>
      Note that the &product-name; EFI support is experimental and will
      be enhanced as EFI matures and becomes more widespread. Mac OS X,
      Linux, and newer Windows guests are known to work fine. Windows 7
      guests are unable to boot with the &product-name; EFI
      implementation.
    </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). Modern OSes,
        such as Mac OS X, generally use GOP, while some older ones still
        use UGA. &product-name; provides a configuration option to
        control the graphics resolution for both interfaces, making the
        difference mostly irrelevant for users.
      </para>

      <para>
        The default resolution is 1024x768. To select a graphics
        resolution for EFI, use the following
        <command>VBoxManage</command> command:
      </para>

<screen>VBoxManage setextradata "VM name" VBoxInternal2/EfiGraphicsResolution HxV</screen>

      <para>
        Determine the horizontal resolution H and the vertical
        resolution V from the following list of default resolutions:
      </para>

      <variablelist>

        <varlistentry>
          <term>
            VGA
          </term>

          <listitem>
            <para>
              640x480, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            SVGA
          </term>

          <listitem>
            <para>
              800x600, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            XGA
          </term>

          <listitem>
            <para>
              1024x768, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            XGA+
          </term>

          <listitem>
            <para>
              1152x864, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            HD
          </term>

          <listitem>
            <para>
              1280x720, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WXGA
          </term>

          <listitem>
            <para>
              1280x800, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            SXGA
          </term>

          <listitem>
            <para>
              1280x1024, 32bpp, 5:4
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            SXGA+
          </term>

          <listitem>
            <para>
              1400x1050, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WXGA+
          </term>

          <listitem>
            <para>
              1440x900, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            HD+
          </term>

          <listitem>
            <para>
              1600x900, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            UXGA
          </term>

          <listitem>
            <para>
              1600x1200, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WSXGA+
          </term>

          <listitem>
            <para>
              1680x1050, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            Full HD
          </term>

          <listitem>
            <para>
              1920x1080, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WUXGA
          </term>

          <listitem>
            <para>
              1920x1200, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            DCI 2K
          </term>

          <listitem>
            <para>
              2048x1080, 32bpp, 19:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            Full HD+
          </term>

          <listitem>
            <para>
              2160x1440, 32bpp, 3:2
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            Unnamed
          </term>

          <listitem>
            <para>
              2304x1440, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            QHD
          </term>

          <listitem>
            <para>
              2560x1440, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WQXGA
          </term>

          <listitem>
            <para>
              2560x1600, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            QWXGA+
          </term>

          <listitem>
            <para>
              2880x1800, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            QHD+
          </term>

          <listitem>
            <para>
              3200x1800, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WQSXGA
          </term>

          <listitem>
            <para>
              3200x2048, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            4K UHD
          </term>

          <listitem>
            <para>
              3840x2160, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WQUXGA
          </term>

          <listitem>
            <para>
              3840x2400, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            DCI 4K
          </term>

          <listitem>
            <para>
              4096x2160, 32bpp, 19:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            HXGA
          </term>

          <listitem>
            <para>
              4096x3072, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            UHD+
          </term>

          <listitem>
            <para>
              5120x2880, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WHXGA
          </term>

          <listitem>
            <para>
              5120x3200, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            WHSXGA
          </term>

          <listitem>
            <para>
              6400x4096, 32bpp, 16:10
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            HUXGA
          </term>

          <listitem>
            <para>
              6400x4800, 32bpp, 4:3
            </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            8K UHD2
          </term>

          <listitem>
            <para>
              7680x4320, 32bpp, 16:9
            </para>
          </listitem>
        </varlistentry>

      </variablelist>

      <para>
        If this list of default resolution does not cover your needs,
        see <xref linkend="customvesa" />. Note that the color depth
        value specified in a custom video mode must be specified. Color
        depths of 8, 16, 24, and 32 are accepted. EFI assumes a color
        depth of 32 by default.
      </para>

      <para>
        The EFI default video resolution settings can only be changed
        when the VM is powered off.
      </para>

    </sect2>

    <sect2 id="efibootargs">

      <title>Specifying Boot Arguments</title>

      <para>
        It is currently not possible to manipulate EFI variables from
        within a running guest. For example, setting the
        <literal>boot-args</literal> variable by running the
        <command>nvram</command> tool in a Mac OS X guest will not work.
        As an alternative method,
        <literal>VBoxInternal2/EfiBootArgs</literal> extradata can be
        passed to a VM in order to set the <literal>boot-args</literal>
        variable. To change the <literal>boot-args</literal> EFI
        variable, use the following command:
      </para>

<screen>VBoxManage setextradata "VM name" VBoxInternal2/EfiBootArgs &lt;value&gt;</screen>

    </sect2>

  </sect1>

</chapter>