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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ Copyright (C) 2006-2022 Oracle and/or its affiliates.
+
+ This file is part of VirtualBox base platform packages, as
+ available from https://www.virtualbox.org.
+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License
+ as published by the Free Software Foundation, in version 3 of the
+ License.
+
+ This program is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, see <https://www.gnu.org/licenses>.
+
+ SPDX-License-Identifier: GPL-3.0-only
+-->
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"[
+<!ENTITY % all.entities SYSTEM "all-entities.ent">
+%all.entities;
+]>
+<chapter id="guestadditions">
+
+ <title>Guest Additions</title>
+
+ <para>
+ The previous chapter covered getting started with &product-name; and
+ installing operating systems in a virtual machine. For any serious
+ and interactive use, the &product-name; Guest Additions will make
+ your life much easier by providing closer integration between host
+ and guest and improving the interactive performance of guest
+ systems. This chapter describes the Guest Additions in detail.
+ </para>
+
+ <sect1 id="guestadd-intro">
+
+ <title>Introduction to Guest Additions</title>
+
+ <para>
+ As mentioned in <xref linkend="virtintro" />, the Guest Additions
+ are designed to be installed <emphasis>inside</emphasis> a virtual
+ machine after the guest operating system has been installed. They
+ consist of device drivers and system applications that optimize
+ the guest operating system for better performance and usability.
+ See <xref linkend="guestossupport" /> for details on what guest
+ operating systems are fully supported with Guest Additions by
+ &product-name;.
+ </para>
+
+ <para>
+ The &product-name; Guest Additions for all supported guest
+ operating systems are provided as a single CD-ROM image file which
+ is called <filename>VBoxGuestAdditions.iso</filename>. This image
+ file is located in the installation directory of &product-name;.
+ To install the Guest Additions for a particular VM, you mount this
+ ISO file in your VM as a virtual CD-ROM and install from there.
+ </para>
+
+ <para>
+ The Guest Additions offer the following features:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Mouse pointer integration</emphasis>. To
+ overcome the limitations for mouse support described in
+ <xref linkend="keyb_mouse_normal" />, this feature provides
+ you with seamless mouse support. You will only have one mouse
+ pointer and pressing the Host key is no longer required to
+ <emphasis>free</emphasis> the mouse from being captured by the
+ guest OS. To make this work, a special mouse driver is
+ installed in the guest that communicates with the physical
+ mouse driver on your host and moves the guest mouse pointer
+ accordingly.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Shared folders.</emphasis> These provide
+ an easy way to exchange files between the host and the guest.
+ Much like ordinary Windows network shares, you can tell
+ &product-name; to treat a certain host directory as a shared
+ folder, and &product-name; will make it available to the guest
+ operating system as a network share, irrespective of whether
+ the guest actually has a network. See
+ <xref linkend="sharedfolders" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Better video support.</emphasis> While
+ the virtual graphics card which &product-name; emulates for
+ any guest operating system provides all the basic features,
+ the custom video drivers that are installed with the Guest
+ Additions provide you with extra high and non-standard video
+ modes, as well as accelerated video performance.
+ </para>
+
+ <para>
+ In addition, with Windows, Linux, and Oracle Solaris guests,
+ you can resize the virtual machine's window if the Guest
+ Additions are installed. The video resolution in the guest
+ will be automatically adjusted, as if you had manually entered
+ an arbitrary resolution in the guest's
+ <emphasis role="bold">Display</emphasis> settings. See
+ <xref linkend="intro-resize-window" />.
+ </para>
+
+ <para>
+ If the Guest Additions are installed, 3D graphics and 2D video
+ for guest applications can be accelerated. See
+ <xref linkend="guestadd-video" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Seamless windows.</emphasis> With this
+ feature, the individual windows that are displayed on the
+ desktop of the virtual machine can be mapped on the host's
+ desktop, as if the underlying application was actually running
+ on the host. See <xref linkend="seamlesswindows" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Generic host/guest communication
+ channels.</emphasis> The Guest Additions enable you to control
+ and monitor guest execution. The <emphasis>guest
+ properties</emphasis> provide a generic string-based mechanism
+ to exchange data bits between a guest and a host, some of
+ which have special meanings for controlling and monitoring the
+ guest. See <xref linkend="guestadd-guestprops" />.
+ </para>
+
+ <para>
+ Additionally, applications can be started in a guest from the
+ host. See <xref linkend="guestadd-guestcontrol" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Time synchronization.</emphasis> With
+ the Guest Additions installed, &product-name; can ensure that
+ the guest's system time is better synchronized with that of
+ the host.
+ </para>
+
+ <para>
+ For various reasons, the time in the guest might run at a
+ slightly different rate than the time on the host. The host
+ could be receiving updates through NTP and its own time might
+ not run linearly. A VM could also be paused, which stops the
+ flow of time in the guest for a shorter or longer period of
+ time. When the wall clock time between the guest and host only
+ differs slightly, the time synchronization service attempts to
+ gradually and smoothly adjust the guest time in small
+ increments to either catch up or lose time. When the
+ difference is too great, for example if a VM paused for hours
+ or restored from saved state, the guest time is changed
+ immediately, without a gradual adjustment.
+ </para>
+
+ <para>
+ The Guest Additions will resynchronize the time regularly. See
+ <xref linkend="changetimesync" /> for how to configure the
+ parameters of the time synchronization mechanism.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Shared clipboard.</emphasis> With the
+ Guest Additions installed, the clipboard of the guest
+ operating system can optionally be shared with your host
+ operating system. See <xref linkend="generalsettings" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Automated logins.</emphasis> Also called
+ credentials passing. See <xref linkend="autologon" />.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Each version of &product-name;, even minor releases, ship with
+ their own version of the Guest Additions. While the interfaces
+ through which the &product-name; core communicates with the Guest
+ Additions are kept stable so that Guest Additions already
+ installed in a VM should continue to work when &product-name; is
+ upgraded on the host, for best results, it is recommended to keep
+ the Guest Additions at the same version.
+ </para>
+
+ <para>
+ The Windows and Linux Guest Additions therefore check
+ automatically whether they have to be updated. If the host is
+ running a newer &product-name; version than the Guest Additions, a
+ notification with further instructions is displayed in the guest.
+ </para>
+
+ <para>
+ To disable this update check for the Guest Additions of a given
+ virtual machine, set the value of its
+ <literal>/VirtualBox/GuestAdd/CheckHostVersion</literal> guest
+ property to <literal>0</literal>. See
+ <xref linkend="guestadd-guestprops" />.
+ </para>
+
+ </sect1>
+
+ <sect1 id="guestadd-install">
+
+ <title>Installing and Maintaining Guest Additions</title>
+
+ <para>
+ Guest Additions are available for virtual machines running
+ Windows, Linux, Oracle Solaris, or OS/2. The following sections
+ describe the specifics of each variant in detail.
+ </para>
+
+ <sect2 id="additions-windows">
+
+ <title>Guest Additions for Windows</title>
+
+ <para>
+ The &product-name; Windows Guest Additions are designed to be
+ installed in a virtual machine running a Windows operating
+ system. The following versions of Windows guests are supported:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Microsoft Windows NT 4.0 (any service pack)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows 2000 (any service pack)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows XP (any service pack)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows Server 2003 (any service pack)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows Server 2008
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows Vista (all editions)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows 7 (all editions)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows 8 (all editions)
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows 10 RTM build 10240
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Microsoft Windows Server 2012
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <sect3 id="mountingadditionsiso">
+
+ <title>Installing the Windows Guest Additions</title>
+
+ <para>
+ In the <emphasis role="bold">Devices</emphasis> menu in the
+ virtual machine's menu bar, &product-name; has a menu item
+ <emphasis role="bold">Insert Guest Additions CD
+ Image</emphasis>, which mounts the Guest Additions ISO file
+ inside your virtual machine. A Windows guest should then
+ automatically start the Guest Additions installer, which
+ installs the Guest Additions on your Windows guest.
+ </para>
+
+ <para>
+ For other guest operating systems, or if automatic start of
+ software on a CD is disabled, you need to do a manual start of
+ the installer.
+ </para>
+
+ <note>
+ <para>
+ For the basic Direct3D acceleration to work in a Windows
+ guest, you have to install the WDDM video driver available
+ for Windows Vista or later.
+ </para>
+
+ <para>
+ For Windows 8 and later, only the WDDM Direct3D video driver
+ is available. For basic Direct3D acceleration to work in
+ Windows XP guests, you have to install the Guest Additions
+ in Safe Mode. See <xref linkend="KnownIssues" /> for
+ details.
+ </para>
+ </note>
+
+ <para>
+ If you prefer to mount the Guest Additions manually, you can
+ perform the following steps:
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ Start the virtual machine in which you have installed
+ Windows.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Select <emphasis role="bold">Optical Drives</emphasis>
+ from the <emphasis role="bold">Devices</emphasis> menu in
+ the virtual machine's menu bar and then
+ <emphasis role="bold">Choose/Create a Disk
+ Image</emphasis>. This displays the Virtual Media Manager,
+ described in <xref linkend="virtual-media-manager" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ In the Virtual Media Manager, click
+ <emphasis role="bold">Add</emphasis> and browse your host
+ file system for the
+ <filename>VBoxGuestAdditions.iso</filename> file.
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ On a Windows host, this file is in the &product-name;
+ installation directory, usually in
+ <filename>C:\Program
+ files\Oracle\VirtualBox</filename>.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ On macOS hosts, this file is in the application bundle
+ of &product-name;. Right-click on the &product-name;
+ icon in Finder and choose <emphasis role="bold">Show
+ Package Contents</emphasis>. The file is located in
+ the <filename>Contents/MacOS</filename> folder.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ On a Linux host, this file is in the
+ <filename>additions</filename> folder where you
+ installed &product-name;, usually
+ <filename>/opt/VirtualBox/</filename>.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ On Oracle Solaris hosts, this file is in the
+ <filename>additions</filename> folder where you
+ installed &product-name;, usually
+ <filename>/opt/VirtualBox</filename>.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+ </listitem>
+
+ <listitem>
+ <para>
+ In the Virtual Media Manager, select the ISO file and
+ click the <emphasis role="bold">Add</emphasis> button.
+ This mounts the ISO file and presents it to your Windows
+ guest as a CD-ROM.
+ </para>
+ </listitem>
+
+ </orderedlist>
+
+ <para>
+ Unless you have the Autostart feature disabled in your Windows
+ guest, Windows will now autostart the &product-name; Guest
+ Additions installation program from the Additions ISO. If the
+ Autostart feature has been turned off, choose
+ <filename>VBoxWindowsAdditions.exe</filename> from the CD/DVD
+ drive inside the guest to start the installer.
+ </para>
+
+ <para>
+ The installer will add several device drivers to the Windows
+ driver database and then invoke the hardware detection wizard.
+ </para>
+
+ <para>
+ Depending on your configuration, it might display warnings
+ that the drivers are not digitally signed. You must confirm
+ these in order to continue the installation and properly
+ install the Additions.
+ </para>
+
+ <para>
+ After installation, reboot your guest operating system to
+ activate the Additions.
+ </para>
+
+ </sect3>
+
+ <sect3 id="additions-windows-updating">
+
+ <title>Updating the Windows Guest Additions</title>
+
+ <para>
+ Windows Guest Additions can be updated by running the
+ installation program again. This replaces the previous
+ Additions drivers with updated versions.
+ </para>
+
+ <para>
+ Alternatively, you can also open the Windows Device Manager
+ and select <emphasis role="bold">Update Driver...</emphasis>
+ for the following devices:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ &product-name; Graphics Adapter
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ &product-name; System Device
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ For each, choose the option to provide your own driver, click
+ <emphasis role="bold">Have Disk</emphasis> and navigate to the
+ CD-ROM drive with the Guest Additions.
+ </para>
+
+ </sect3>
+
+ <sect3 id="additions-windows-install-unattended">
+
+ <title>Unattended Installation of the Windows Guest Additions</title>
+
+ <para>
+ You can configure unattended installation of the
+ &product-name; Guest Additions when you create a new VM using
+ the <emphasis role="bold">Create Virtual Machine</emphasis>
+ wizard. Select the <emphasis role="bold">Guest
+ Additions</emphasis> check box on the
+ <emphasis role="bold">Unattended Guest OS Install</emphasis>
+ page of the wizard.
+ </para>
+
+ <para>
+ Guest Additions are installed automatically, following
+ completion of the guest OS installation.
+ </para>
+
+ <simplesect id="additions-windows-install-unattended-certs">
+
+ <title>Installing Code Signing Certificates</title>
+
+ <para>
+ To avoid popups when performing an unattended installation
+ of the &product-name; Guest Additions, the code signing
+ certificates used to sign the drivers needs to be installed
+ in the correct certificate stores on the guest operating
+ system. Failure to do this will cause a typical Windows
+ installation to display multiple dialogs asking whether you
+ want to install a particular driver.
+ </para>
+
+ <note>
+ <para>
+ On some legacy Windows versions, such as Windows 2000 and
+ Windows XP, the user intervention popups mentioned above
+ are always displayed, even after importing the Oracle
+ certificates.
+ </para>
+ </note>
+
+ <para>
+ Installing the code signing certificates on a Windows guest
+ can be done automatically. Use the
+ <filename>VBoxCertUtil.exe</filename> utility from the
+ <filename>cert</filename> folder on the Guest Additions
+ installation CD.
+ </para>
+
+ <para>
+ Use the following steps:
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ Log in as Administrator on the guest.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Mount the &product-name; Guest Additions .ISO.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Open a command line window on the guest and change to
+ the <filename>cert</filename> folder on the
+ &product-name; Guest Additions CD.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Run the following command:
+ </para>
+
+<screen>VBoxCertUtil.exe add-trusted-publisher vbox*.cer --root vbox*.cer</screen>
+
+ <para>
+ This command installs the certificates to the
+ certificate store. When installing the same certificate
+ more than once, an appropriate error will be displayed.
+ </para>
+ </listitem>
+
+ </orderedlist>
+
+ <para>
+ To allow for completely unattended guest installations, you
+ can specify a command line parameter to the install
+ launcher:
+ </para>
+
+<screen>VBoxWindowsAdditions.exe /S</screen>
+
+ <para>
+ This automatically installs the right files and drivers for
+ the corresponding platform, either 32-bit or 64-bit.
+ </para>
+
+ <note>
+ <para>
+ By default on an unattended installation on a Vista or
+ Windows 7 guest, there will be the XPDM graphics driver
+ installed. This graphics driver does not support Windows
+ Aero / Direct3D on the guest. Instead, the WDDM graphics
+ driver needs to be installed. To select this driver by
+ default, add the command line parameter
+ <literal>/with_wddm</literal> when invoking the Windows
+ Guest Additions installer. This is only required for Vista
+ and Windows 7.
+ </para>
+ </note>
+
+ <note>
+ <para>
+ For Windows Aero to run correctly on a guest, the guest's
+ VRAM size needs to be configured to at least 128 MB.
+ </para>
+ </note>
+
+ <para>
+ For more options regarding unattended guest installations,
+ consult the command line help by using the command:
+ </para>
+
+<screen>VBoxWindowsAdditions.exe /?</screen>
+
+ </simplesect>
+
+ </sect3>
+
+ <sect3 id="windows-guest-file-extraction">
+
+ <title>Manual File Extraction</title>
+
+ <para>
+ If you would like to install the files and drivers manually,
+ you can extract the files from the Windows Guest Additions
+ setup as follows:
+ </para>
+
+<screen>VBoxWindowsAdditions.exe /extract</screen>
+
+ <para>
+ To explicitly extract the Windows Guest Additions for another
+ platform than the current running one, such as 64-bit files on
+ a 32-bit system, you must use the appropriate platform
+ installer. Use
+ <filename>VBoxWindowsAdditions-x86.exe</filename> or
+ <filename>VBoxWindowsAdditions-amd64.exe</filename> with the
+ <literal>/extract</literal> parameter.
+ </para>
+
+ </sect3>
+
+ </sect2>
+
+ <sect2 id="additions-linux">
+
+ <title>Guest Additions for Linux</title>
+
+ <para>
+ Like the Windows Guest Additions, the &product-name; Guest
+ Additions for Linux are a set of device drivers and system
+ applications which may be installed in the guest operating
+ system.
+ </para>
+
+ <para>
+ The following Linux distributions are officially supported:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Oracle Linux as of version 5, including UEK kernels
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Fedora as of Fedora Core 4
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Red Hat Enterprise Linux as of version 3
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ SUSE and openSUSE Linux as of version 9
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Ubuntu as of version 5.10
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Many other distributions are known to work with the Guest
+ Additions.
+ </para>
+
+ <para>
+ The version of the Linux kernel supplied by default in SUSE and
+ openSUSE 10.2, Ubuntu 6.10 (all versions) and Ubuntu 6.06
+ (server edition) contains a bug which can cause it to crash
+ during startup when it is run in a virtual machine. The Guest
+ Additions work in those distributions.
+ </para>
+
+ <para>
+ Note that some Linux distributions already come with all or part
+ of the &product-name; Guest Additions. You may choose to keep
+ the distribution's version of the Guest Additions but these are
+ often not up to date and limited in functionality, so we
+ recommend replacing them with the Guest Additions that come with
+ &product-name;. The &product-name; Linux Guest Additions
+ installer tries to detect an existing installation and replace
+ them but depending on how the distribution integrates the Guest
+ Additions, this may require some manual interaction. It is
+ highly recommended to take a snapshot of the virtual machine
+ before replacing preinstalled Guest Additions.
+ </para>
+
+ <sect3 id="additions-linux-install">
+
+ <title>Installing the Linux Guest Additions</title>
+
+ <para>
+ The &product-name; Guest Additions for Linux are provided on
+ the same virtual CD-ROM file as the Guest Additions for
+ Windows. See <xref linkend="mountingadditionsiso"/>. They also
+ come with an installation program that guides you through the
+ setup process. However, due to the significant differences
+ between Linux distributions, installation may be slightly more
+ complex when compared to Windows.
+ </para>
+
+ <para>
+ Installation generally involves the following steps:
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ Before installing the Guest Additions, you prepare your
+ guest system for building external kernel modules. This
+ works as described in
+ <xref linkend="externalkernelmodules" />, except that this
+ step must be performed in your Linux
+ <emphasis>guest</emphasis> instead of on a Linux host
+ system.
+ </para>
+
+ <para>
+ If you suspect that something has gone wrong, check that
+ your guest is set up correctly and run the following
+ command as root:
+ </para>
+
+<screen>rcvboxadd setup</screen>
+ </listitem>
+
+ <listitem>
+ <para>
+ Insert the <filename>VBoxGuestAdditions.iso</filename> CD
+ file into your Linux guest's virtual CD-ROM drive, as
+ described for a Windows guest in
+ <xref linkend="mountingadditionsiso" />.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Change to the directory where your CD-ROM drive is mounted
+ and run the following command as root:
+ </para>
+
+<screen>sh ./VBoxLinuxAdditions.run</screen>
+ </listitem>
+
+ </orderedlist>
+
+ </sect3>
+
+ <sect3 id="additions-linux-install-unattended">
+
+ <title>Unattended Installation of the Linux Guest Additions</title>
+
+ <para>
+ You can configure unattended installation of the
+ &product-name; Guest Additions when you create a new VM using
+ the <emphasis role="bold">Create Virtual Machine</emphasis>
+ wizard. Select the <emphasis role="bold">Guest
+ Additions</emphasis> check box on the
+ <emphasis role="bold">Unattended Guest OS Install</emphasis>
+ page of the wizard.
+ </para>
+
+ <para>
+ Guest Additions are installed automatically, following
+ completion of the guest OS installation.
+ </para>
+
+ </sect3>
+
+ <sect3 id="additions-linux-graphics-mouse">
+
+ <title>Graphics and Mouse Integration</title>
+
+ <para>
+ In Linux and Oracle Solaris guests, &product-name; graphics
+ and mouse integration goes through the X Window System.
+ &product-name; can use the X.Org variant of the system, or
+ XFree86 version 4.3 which is identical to the first X.Org
+ release. During the installation process, the X.Org display
+ server will be set up to use the graphics and mouse drivers
+ which come with the Guest Additions.
+ </para>
+
+ <para>
+ After installing the Guest Additions into a fresh installation
+ of a supported Linux distribution or Oracle Solaris system,
+ many unsupported systems will work correctly too, the guest's
+ graphics mode will change to fit the size of the
+ &product-name; window on the host when it is resized. You can
+ also ask the guest system to switch to a particular resolution
+ by sending a video mode hint using the
+ <command>VBoxManage</command> tool.
+ </para>
+
+ <para>
+ Multiple guest monitors are supported in guests using the
+ X.Org server version 1.3, which is part of release 7.3 of the
+ X Window System version 11, or a later version. The layout of
+ the guest screens can be adjusted as needed using the tools
+ which come with the guest operating system.
+ </para>
+
+ <para>
+ If you want to understand more about the details of how the
+ X.Org drivers are set up, in particular if you wish to use
+ them in a setting which our installer does not handle
+ correctly, see <xref linkend="guestxorgsetup" />.
+ </para>
+
+ <para>
+ Starting from &product-name; 7, Linux guest screen resize
+ functionality for guests running VMSVGA graphics configuration
+ has been changed. Since then, this functionality consists of a
+ standalone daemon called VBoxDRMClient and its Desktop
+ Environment helper counterpart.
+ </para>
+
+ <para>
+ VBoxDRMClient runs as a root process and is a bridge between
+ the host and the guest's vmwgfx driver. This means that
+ VBoxDRMClient listens to screen resize hints from the host and
+ forwards them to the vmwgfx driver. This enables guest screen
+ resize functionality to be available before the user has
+ performed a graphical login.
+ </para>
+
+ <para>
+ In order to perform Desktop Environment specific actions, such
+ as setting the primary screen in a multimonitor setup, a
+ Desktop Environment helper is used. Once the user has
+ performed a graphical login operation, the helper daemon
+ starts with user session scope and attempts to connect to
+ VBoxDRMClient using an IPC connection. When VBoxDRMClient has
+ received a corresponding command from the host, it is
+ forwarded to the helper daemon over IPC and the action is then
+ performed.
+ </para>
+
+ <para>
+ By default, VBoxDRMClient allows any process to connect to its
+ IPC socket. This can be restricted by using the following
+ steps:
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ The Guest Additions Linux installer creates a
+ <literal>vboxdrmipc</literal> user group. A corresponding
+ user needs to be added to this group.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ You must set the <literal>DRMIpcRestricted</literal> guest
+ property, as follows:
+ </para>
+
+<screen>VBoxManage guestproperty set "VM name" /VirtualBox/GuestAdd/DRMIpcRestricted 1 \
+--flags RDONLYGUEST</screen>
+
+ <para>
+ It is important to set only the RDONLYGUEST flag for the
+ property, so that it cannot be changed from inside the
+ guest.
+ </para>
+ </listitem>
+
+ </orderedlist>
+
+ <note>
+ <para>
+ Both steps are required. If one of them is missing, all
+ processes will have access to the IPC socket.
+ </para>
+ </note>
+
+ <para>
+ Restricted mode can be disabled by unsetting the guest
+ property, as follows:
+ </para>
+
+<screen>VBoxManage guestproperty unset "VM name" /VirtualBox/GuestAdd/DRMIpcRestricted</screen>
+
+ </sect3>
+
+ <sect3 id="additions-linux-updating">
+
+ <title>Updating the Linux Guest Additions</title>
+
+ <para>
+ The Guest Additions can simply be updated by going through the
+ installation procedure again with an updated CD-ROM image.
+ This will replace the drivers with updated versions. You
+ should reboot after updating the Guest Additions.
+ </para>
+
+ </sect3>
+
+ <sect3 id="additions-linux-uninstall">
+
+ <title>Uninstalling the Linux Guest Additions</title>
+
+ <para>
+ If you have a version of the Guest Additions installed on your
+ virtual machine and wish to remove it without installing new
+ ones, you can do so by inserting the Guest Additions CD image
+ into the virtual CD-ROM drive as described above. Then run the
+ installer for the current Guest Additions with the
+ <literal>uninstall</literal> parameter from the path that the
+ CD image is mounted on in the guest, as follows:
+ </para>
+
+<screen>sh ./VBoxLinuxAdditions.run uninstall</screen>
+
+ <para>
+ While this will normally work without issues, you may need to
+ do some manual cleanup of the guest in some cases, especially
+ of the XFree86Config or xorg.conf file. In particular, if the
+ Additions version installed or the guest operating system were
+ very old, or if you made your own changes to the Guest
+ Additions setup after you installed them.
+ </para>
+
+ <para>
+ You can uninstall the Additions as follows:
+ </para>
+
+<screen>/opt/VBoxGuestAdditions-<replaceable>version</replaceable>/uninstall.sh</screen>
+
+ <para>
+ Replace
+ <filename>/opt/VBoxGuestAdditions-<replaceable>version</replaceable></filename>
+ with the correct Guest Additions installation directory.
+ </para>
+
+ </sect3>
+
+ </sect2>
+
+ <sect2 id="additions-solaris">
+
+ <title>Guest Additions for Oracle Solaris</title>
+
+ <para>
+ Like the Windows Guest Additions, the &product-name; Guest
+ Additions for Oracle Solaris take the form of a set of device
+ drivers and system applications which may be installed in the
+ guest operating system.
+ </para>
+
+ <para>
+ The following Oracle Solaris distributions are officially
+ supported:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Oracle Solaris 11, including Oracle Solaris 11 Express
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Oracle Solaris 10 4/08 and later
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Other distributions may work if they are based on comparable
+ software releases.
+ </para>
+
+ <sect3 id="additions-solaris-install">
+
+ <title>Installing the Oracle Solaris Guest Additions</title>
+
+ <para>
+ The &product-name; Guest Additions for Oracle Solaris are
+ provided on the same ISO CD-ROM as the Additions for Windows
+ and Linux. They come with an installation program that guides
+ you through the setup process.
+ </para>
+
+ <para>
+ Installation involves the following steps:
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ Mount the <filename>VBoxGuestAdditions.iso</filename> file
+ as your Oracle Solaris guest's virtual CD-ROM drive,
+ exactly the same way as described for a Windows guest in
+ <xref linkend="mountingadditionsiso" />.
+ </para>
+
+ <para>
+ If the CD-ROM drive on the guest does not get mounted, as
+ seen with some versions of Oracle Solaris 10, run the
+ following command as root:
+ </para>
+
+<screen>svcadm restart volfs</screen>
+ </listitem>
+
+ <listitem>
+ <para>
+ Change to the directory where your CD-ROM drive is mounted
+ and run the following command as root:
+ </para>
+
+<screen>pkgadd -G -d ./VBoxSolarisAdditions.pkg</screen>
+ </listitem>
+
+ <listitem>
+ <para>
+ Choose <emphasis role="bold">1</emphasis> and confirm
+ installation of the Guest Additions package. After the
+ installation is complete, log out and log in to X server
+ on your guest, to activate the X11 Guest Additions.
+ </para>
+ </listitem>
+
+ </orderedlist>
+
+ </sect3>
+
+ <sect3 id="additions-solaris-install-unattended">
+
+ <title>Unattended Installation of the Oracle Solaris Guest Additions</title>
+
+ <para>
+ You can configure unattended installation of the
+ &product-name; Guest Additions when you create a new VM using
+ the <emphasis role="bold">Create Virtual Machine</emphasis>
+ wizard. Select the <emphasis role="bold">Guest
+ Additions</emphasis> check box on the
+ <emphasis role="bold">Unattended Guest OS Install</emphasis>
+ page of the wizard.
+ </para>
+
+ <para>
+ Guest Additions are installed automatically, following
+ completion of the guest OS installation.
+ </para>
+
+ </sect3>
+
+ <sect3 id="additions-solaris-uninstall">
+
+ <title>Uninstalling the Oracle Solaris Guest Additions</title>
+
+ <para>
+ The Oracle Solaris Guest Additions can be safely removed by
+ removing the package from the guest. Open a root terminal
+ session and run the following command:
+ </para>
+
+<screen>pkgrm SUNWvboxguest</screen>
+
+ </sect3>
+
+ <sect3 id="additions-solaris-updating">
+
+ <title>Updating the Oracle Solaris Guest Additions</title>
+
+ <para>
+ The Guest Additions should be updated by first uninstalling
+ the existing Guest Additions and then installing the new ones.
+ Attempting to install new Guest Additions without removing the
+ existing ones is not possible.
+ </para>
+
+ </sect3>
+
+ </sect2>
+
+ <sect2 id="additions-os2">
+
+ <title>Guest Additions for OS/2</title>
+
+ <para>
+ &product-name; also ships with a set of drivers that improve
+ running OS/2 in a virtual machine. Due to restrictions of OS/2
+ itself, this variant of the Guest Additions has a limited
+ feature set. See <xref linkend="KnownIssues" /> for details.
+ </para>
+
+ <para>
+ The OS/2 Guest Additions are provided on the same ISO CD-ROM as
+ those for the other platforms. Mount the ISO in OS/2 as
+ described previously. The OS/2 Guest Additions are located in
+ the directory <filename>\OS2</filename>.
+ </para>
+
+ <para>
+ We do not provide an automatic installer at this time. See the
+ <filename>readme.txt</filename> file in the CD-ROM directory,
+ which describes how to install the OS/2 Guest Additions
+ manually.
+ </para>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="sharedfolders">
+
+ <title>Shared Folders</title>
+
+ <para>
+ With the <emphasis>shared folders</emphasis> feature of
+ &product-name;, you can access files of your host system from
+ within the guest system. This is similar to how you would use
+ network shares in Windows networks, except that shared folders do
+ not require networking, only the Guest Additions. Shared folders
+ are supported with Windows 2000 or later, Linux, and Oracle
+ Solaris guests. &product-name; includes experimental support for
+ Mac OS X and OS/2 guests.
+ </para>
+
+ <para>
+ Shared folders physically reside on the <emphasis>host</emphasis>
+ and are then shared with the guest, which uses a special file
+ system driver in the Guest Additions to talk to the host. For
+ Windows guests, shared folders are implemented as a pseudo-network
+ redirector. For Linux and Oracle Solaris guests, the Guest
+ Additions provide a virtual file system.
+ </para>
+
+ <para>
+ To share a host folder with a virtual machine in &product-name;,
+ you must specify the path of the folder and choose a
+ <emphasis>share name</emphasis> that the guest can use to access
+ the shared folder. This happens on the host. In the guest you can
+ then use the share name to connect to it and access files.
+ </para>
+
+ <para>
+ There are several ways in which shared folders can be set up for a
+ virtual machine:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ In the window of a running VM, you select
+ <emphasis role="bold">Shared Folders</emphasis> from the
+ <emphasis role="bold">Devices</emphasis> menu, or click on the
+ folder icon on the status bar in the bottom right corner.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ If a VM is not currently running, you can configure shared
+ folders in the virtual machine's
+ <emphasis role="bold">Settings</emphasis> window.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ From the command line, you can create shared folders using
+ <command>VBoxManage</command>, as follows:
+ </para>
+
+<screen>VBoxManage sharedfolder add "VM name" --name "sharename" --hostpath "C:\test"</screen>
+
+ <para>
+ See <xref linkend="vboxmanage-sharedfolder" />.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ There are two types of shares:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Permanent shares, that are saved with the VM settings.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Transient shares, that are added at runtime and disappear when
+ the VM is powered off. These can be created using a check box
+ in &vbox-mgr;, or by using the <option>--transient</option>
+ option of the <command>VBoxManage sharedfolder add</command>
+ command.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Shared folders can either be read-write or read-only. This means
+ that the guest is either allowed to both read and write, or just
+ read files on the host. By default, shared folders are read-write.
+ Read-only folders can be created using a check box in the
+ &vbox-mgr;, or with the <option>--readonly</option> option of the
+ <command>VBoxManage sharedfolder add</command> command.
+ </para>
+
+ <para>
+ &product-name; shared folders also support symbolic links, also
+ called <emphasis>symlinks</emphasis>, under the following
+ conditions:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ The host operating system must support symlinks. For example,
+ a macOS, Linux, or Oracle Solaris host is required.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Currently only Linux and Oracle Solaris Guest Additions
+ support symlinks.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ For security reasons the guest OS is not allowed to create
+ symlinks by default. If you trust the guest OS to not abuse
+ the functionality, you can enable creation of symlinks for a
+ shared folder as follows:
+ </para>
+
+<screen>VBoxManage setextradata "VM name" VBoxInternal2/SharedFoldersEnableSymlinksCreate/<replaceable>sharename</replaceable> 1</screen>
+ </listitem>
+
+ </itemizedlist>
+
+ <sect2 id="sf_mount_manual">
+
+ <title>Manual Mounting</title>
+
+ <para>
+ You can mount the shared folder from inside a VM, in the same
+ way as you would mount an ordinary network share:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ In a Windows guest, shared folders are browseable and
+ therefore visible in Windows Explorer. To attach the host's
+ shared folder to your Windows guest, open Windows Explorer
+ and look for the folder in <emphasis role="bold">My
+ Networking Places</emphasis>, <emphasis role="bold">Entire
+ Network</emphasis>, <emphasis role="bold">&product-name;
+ Shared Folders</emphasis>. By right-clicking on a shared
+ folder and selecting <emphasis role="bold">Map Network
+ Drive</emphasis> from the menu that pops up, you can assign
+ a drive letter to that shared folder.
+ </para>
+
+ <para>
+ Alternatively, on the Windows command line, use the
+ following command:
+ </para>
+
+<screen>net use x: \\vboxsvr\sharename</screen>
+
+ <para>
+ While <literal>vboxsvr</literal> is a fixed name, note that
+ <literal>vboxsrv</literal> would also work, replace
+ <replaceable>x:</replaceable> with the drive letter that you
+ want to use for the share, and
+ <replaceable>sharename</replaceable> with the share name
+ specified with <command>VBoxManage</command>.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ In a Linux guest, use the following command:
+ </para>
+
+<screen>mount -t vboxsf [-o OPTIONS] sharename mountpoint</screen>
+
+ <para>
+ To mount a shared folder during boot, add the following
+ entry to <filename>/etc/fstab</filename>:
+ </para>
+
+<screen>sharename mountpoint vboxsf defaults 0 0</screen>
+ </listitem>
+
+ <listitem>
+ <para>
+ In a Oracle Solaris guest, use the following command:
+ </para>
+
+<screen>mount -F vboxfs [-o OPTIONS] sharename mountpoint</screen>
+
+ <para>
+ Replace <replaceable>sharename</replaceable>, use a
+ lowercase string, with the share name specified with
+ <command>VBoxManage</command> or &vbox-mgr;. Replace
+ <replaceable>mountpoint</replaceable> with the path where
+ you want the share to be mounted on the guest, such as
+ <filename>/mnt/share</filename>. The usual mount rules
+ apply. For example, create this directory first if it does
+ not exist yet.
+ </para>
+
+ <para>
+ Here is an example of mounting the shared folder for the
+ user jack on Oracle Solaris:
+ </para>
+
+<screen>$ id
+uid=5000(jack) gid=1(other)
+$ mkdir /export/home/jack/mount
+$ pfexec mount -F vboxfs -o uid=5000,gid=1 jackshare /export/home/jack/mount
+$ cd ~/mount
+$ ls
+sharedfile1.mp3 sharedfile2.txt
+$</screen>
+
+ <para>
+ Beyond the standard options supplied by the
+ <command>mount</command> command, the following are
+ available:
+ </para>
+
+<screen>iocharset CHARSET</screen>
+
+ <para>
+ This option sets the character set used for I/O operations.
+ Note that on Linux guests, if the
+ <literal>iocharset</literal> option is not specified, then
+ the Guest Additions driver will attempt to use the character
+ set specified by the CONFIG_NLS_DEFAULT kernel option. If
+ this option is not set either, then UTF-8 is used.
+ </para>
+
+<screen>convertcp CHARSET</screen>
+
+ <para>
+ This option specifies the character set used for the shared
+ folder name. This is UTF-8 by default.
+ </para>
+
+ <para>
+ The generic mount options, documented in the
+ <command>mount</command> manual page, apply also. Especially
+ useful are the options <literal>uid</literal>,
+ <literal>gid</literal> and <literal>mode</literal>, as they
+ can allow access by normal users in read/write mode,
+ depending on the settings, even if root has mounted the
+ filesystem.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ In an OS/2 guest, use the <command>VBoxControl</command>
+ command to manage shared folders. For example:
+ </para>
+
+<screen>VBoxControl sharedfolder use D: MyShareName
+VBoxControl sharedfolder unuse D:
+VBoxControl sharedfolder list</screen>
+
+ <para>
+ As with Windows guests, shared folders can also be accessed
+ via UNC using <filename>\\VBoxSF\</filename>,
+ <filename>\\VBoxSvr\</filename> or
+ <filename>\\VBoxSrv\</filename> as the server name and the
+ shared folder name as <replaceable>sharename</replaceable>.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ </sect2>
+
+ <sect2 id="sf_mount_auto">
+
+ <title>Automatic Mounting</title>
+
+ <para>
+ &product-name; provides the option to mount shared folders
+ automatically. When automatic mounting is enabled for a shared
+ folder, the Guest Additions service will mount it for you
+ automatically. For Windows or OS/2, a preferred drive letter can
+ also be specified. For Linux or Oracle Solaris, a mount point
+ directory can also be specified.
+ </para>
+
+ <para>
+ If a drive letter or mount point is not specified, or is in use
+ already, an alternative location is found by the Guest Additions
+ service. The service searches for an alternative location
+ depending on the guest OS, as follows:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Windows and OS/2 guests.</emphasis>
+ Search for a free drive letter, starting at
+ <filename>Z:</filename>. If all drive letters are assigned,
+ the folder is not mounted.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Linux and Oracle Solaris
+ guests.</emphasis> Folders are mounted under the
+ <filename>/media</filename> directory. The folder name is
+ normalized (no spaces, slashes or colons) and is prefixed
+ with <filename>sf_</filename>.
+ </para>
+
+ <para>
+ For example, if you have a shared folder called
+ <filename>myfiles</filename>, it will appear as
+ <filename>/media/sf_myfiles</filename> in the guest.
+ </para>
+
+ <para>
+ The guest properties
+ <literal>/VirtualBox/GuestAdd/SharedFolders/MountDir</literal>
+ and the more generic
+ <literal>/VirtualBox/GuestAdd/SharedFolders/MountPrefix</literal>
+ can be used to override the automatic mount directory and
+ prefix. See <xref linkend="guestadd-guestprops" />.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Access to an automatically mounted shared folder is granted to
+ everyone in a Windows guest, including the guest user. For Linux
+ and Oracle Solaris guests, access is restricted to members of
+ the group <literal>vboxsf</literal> and the
+ <literal>root</literal> user.
+ </para>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="guestadd-dnd">
+
+ <title>Drag and Drop</title>
+
+ <para>
+ &product-name; enables you to drag and drop content from the host
+ to the guest, and vice versa. For this to work the latest version
+ of the Guest Additions must be installed on the guest.
+ </para>
+
+ <para>
+ Drag and drop transparently allows copying or opening files,
+ directories, and even certain clipboard formats from one end to
+ the other. For example, from the host to the guest or from the
+ guest to the host. You then can perform drag and drop operations
+ between the host and a VM, as it would be a native drag and drop
+ operation on the host OS.
+ </para>
+
+ <para>
+ At the moment drag and drop is implemented for Windows-based and
+ X-Windows-based systems, both on the host and guest side. As
+ X-Windows supports many different drag and drop protocols only the
+ most common one, XDND, is supported for now. Applications using
+ other protocols, such as Motif or OffiX, will not be recognized by
+ &product-name;.
+ </para>
+
+ <para>
+ In the context of using drag and drop, the origin of the data is
+ called the <emphasis>source</emphasis>. That is, where the actual
+ data comes from and is specified. The
+ <emphasis>destination</emphasis> specifies where the data from the
+ source should go to. Transferring data from the source to the
+ destination can be done in various ways, such as copying, moving,
+ or linking.
+ </para>
+
+ <note>
+ <para>
+ At the moment only copying of data is supported. Moving or
+ linking is not yet implemented.
+ </para>
+ </note>
+
+ <para>
+ When transferring data from the host to the guest OS, the host in
+ this case is the source, whereas the guest OS is the destination.
+ However, when transferring data from the guest OS to the host, the
+ guest OS this time became the source and the host is the
+ destination.
+ </para>
+
+ <para>
+ For security reasons drag and drop can be configured at runtime on
+ a per-VM basis either using the <emphasis role="bold">Drag and
+ Drop</emphasis> menu item in the
+ <emphasis role="bold">Devices</emphasis> menu of the virtual
+ machine, as shown below, or the <command>VBoxManage</command>
+ command.
+ </para>
+
+ <figure id="fig-drag-drop-options">
+ <title>Drag and Drop Menu Options</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center" fileref="images/dnd-modes.png"
+ width="10cm" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ The following drag and drop modes are available:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Disabled.</emphasis> Disables the drag
+ and drop feature entirely. This is the default when creating a
+ new VM.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Host To Guest.</emphasis> Enables drag
+ and drop operations from the host to the guest only.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Guest To Host.</emphasis> Enables drag
+ and drop operations from the guest to the host only.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Bidirectional.</emphasis> Enables drag
+ and drop operations in both directions: from the host to the
+ guest, and from the guest to the host.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <note>
+ <para>
+ Drag and drop support depends on the frontend being used. At the
+ moment, only the &vbox-mgr; frontend provides this
+ functionality.
+ </para>
+ </note>
+
+ <para>
+ To use the <command>VBoxManage</command> command to control the
+ current drag and drop mode, see <xref linkend="vboxmanage" />. The
+ <command>modifyvm</command> and <command>controlvm</command>
+ commands enable setting of a VM's current drag and drop mode from
+ the command line.
+ </para>
+
+ <sect2 id="guestadd-dnd-formats">
+
+ <title>Supported Formats</title>
+
+ <para>
+ As &product-name; can run on a variety of host operating systems
+ and also supports a wide range of guests, certain data formats
+ must be translated after transfer. This is so that the
+ destination operating system, which receives the data, is able
+ to handle them in an appropriate manner.
+ </para>
+
+ <note>
+ <para>
+ When dragging files no data conversion is done in any way. For
+ example, when transferring a file from a Linux guest to a
+ Windows host the Linux-specific line endings are not converted
+ to Windows line endings.
+ </para>
+ </note>
+
+ <para>
+ The following formats are handled by the &product-name; drag and
+ drop service:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Plain text:</emphasis> From
+ applications such as text editors, internet browsers and
+ terminal windows.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Files:</emphasis> From file managers
+ such as Windows Explorer, Nautilus, and Finder.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ <emphasis role="bold">Directories:</emphasis> For
+ directories, the same formats apply as for files.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ </sect2>
+
+ <sect2 id="guestadd-dnd-limitations">
+
+ <title>Known Limitations</title>
+
+ <para>
+ The following limitations are known for drag and drop:
+ </para>
+
+ <para>
+ On Windows hosts, dragging and dropping content between
+ UAC-elevated (User Account Control) programs and
+ non-UAC-elevated programs is not allowed. If you start
+ &product-name; with Administrator privileges then drag and drop
+ will not work with Windows Explorer, which runs with regular
+ user privileges by default.
+ </para>
+
+ <para>
+ On Linux hosts and guests, programs can query for drag and drop
+ data while the drag operation is still in progress. For example,
+ on LXDE using the PCManFM file manager. This currently is not
+ supported. As a workaround, a different file manager, such as
+ Nautilus, can be used instead.
+ </para>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="guestadd-video">
+
+ <title>Hardware-Accelerated Graphics</title>
+
+ <sect2 id="guestadd-3d">
+
+ <title>Hardware 3D Acceleration (OpenGL and Direct3D 8/9)</title>
+
+ <para>
+ The &product-name; Guest Additions contain experimental hardware
+ 3D support for Windows, Linux, and Oracle Solaris guests.
+ </para>
+
+ <para>
+ With this feature, if an application inside your virtual machine
+ uses 3D features through the OpenGL or Direct3D 8/9 programming
+ interfaces, instead of emulating them in software, which would
+ be slow, &product-name; will attempt to use your host's 3D
+ hardware. This works for all supported host platforms, provided
+ that your host operating system can make use of your accelerated
+ 3D hardware in the first place.
+ </para>
+
+ <para>
+ The 3D acceleration feature currently has the following
+ preconditions:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ It is only available for certain Windows, Linux, and Oracle
+ Solaris guests. In particular:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ 3D acceleration with Windows guests requires Windows
+ 2000 or later. Apart from on Windows 2000 guests, both
+ OpenGL and Direct3D 8/9 are supported on an experimental
+ basis.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ OpenGL on Linux requires kernel 2.6.27 or later, as well
+ as X.org server version 1.5 or later. Ubuntu 10.10 and
+ Fedora 14 have been tested and confirmed as working.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ OpenGL on Oracle Solaris guests requires X.org server
+ version 1.5 or later.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+ </listitem>
+
+ <listitem>
+ <para>
+ The Guest Additions must be installed.
+ </para>
+
+ <note>
+ <para>
+ For the basic Direct3D acceleration to work in a Windows
+ Guest, &product-name; needs to replace Windows system
+ files in the virtual machine. As a result, the Guest
+ Additions installation program offers Direct3D
+ acceleration as an option that must be explicitly enabled.
+ Also, you must install the Guest Additions in Safe Mode.
+ This does <emphasis>not</emphasis> apply to the WDDM
+ Direct3D video driver available for Windows Vista and
+ later. See <xref linkend="KnownIssues" /> for details.
+ </para>
+ </note>
+ </listitem>
+
+ <listitem>
+ <para>
+ Because 3D support is still experimental at this time, it is
+ disabled by default and must be <emphasis>manually
+ enabled</emphasis> in the VM settings. See
+ <xref linkend="settings-display" />.
+ </para>
+
+ <note>
+ <para>
+ Untrusted guest systems should not be allowed to use the
+ 3D acceleration features of &product-name;, just as
+ untrusted host software should not be allowed to use 3D
+ acceleration. Drivers for 3D hardware are generally too
+ complex to be made properly secure and any software which
+ is allowed to access them may be able to compromise the
+ operating system running them. In addition, enabling 3D
+ acceleration gives the guest direct access to a large body
+ of additional program code in the &product-name; host
+ process which it might conceivably be able to use to crash
+ the virtual machine.
+ </para>
+ </note>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ To enable Aero theme support, the &product-name; WDDM video
+ driver must be installed, which is available with the Guest
+ Additions installation. The WDDM driver is not installed by
+ default for Vista and Windows 7 guests and must be
+ <emphasis>manually selected</emphasis> in the Guest Additions
+ installer by clicking <emphasis role="bold">No</emphasis> in the
+ <emphasis role="bold">Would You Like to Install Basic Direct3D
+ Support</emphasis> dialog displayed when the Direct3D feature is
+ selected.
+ </para>
+
+ <para>
+ The Aero theme is not enabled by default on Windows. See your
+ Windows platform documentation for details of how to enable the
+ Aero theme.
+ </para>
+
+ <para>
+ Technically, &product-name; implements 3D acceleration by
+ installing an additional hardware 3D driver inside the guest
+ when the Guest Additions are installed. This driver acts as a
+ hardware 3D driver and reports to the guest operating system
+ that the virtual hardware is capable of 3D hardware
+ acceleration. When an application in the guest then requests
+ hardware acceleration through the OpenGL or Direct3D programming
+ interfaces, these are sent to the host through a special
+ communication tunnel implemented by &product-name;. The
+ <emphasis>host</emphasis> then performs the requested 3D
+ operation using the host's programming interfaces.
+ </para>
+
+ </sect2>
+
+ <sect2 id="guestadd-2d">
+
+ <title>Hardware 2D Video Acceleration for Windows Guests</title>
+
+ <para>
+ The &product-name; Guest Additions contain experimental hardware
+ 2D video acceleration support for Windows guests.
+ </para>
+
+ <para>
+ With this feature, if an application such as a video player
+ inside your Windows VM uses 2D video overlays to play a movie
+ clip, then &product-name; will attempt to use your host's video
+ acceleration hardware instead of performing overlay stretching
+ and color conversion in software, which would be slow. This
+ currently works for Windows, Linux and macOS host platforms,
+ provided that your host operating system can make use of 2D
+ video acceleration in the first place.
+ </para>
+
+ <para>
+ Hardware 2D video acceleration currently has the following
+ preconditions:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Only available for Windows guests, running Windows XP or
+ later.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Guest Additions must be installed.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Because 2D support is still experimental at this time, it is
+ disabled by default and must be <emphasis>manually
+ enabled</emphasis> in the VM settings. See
+ <xref linkend="settings-display" />.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ Technically, &product-name; implements this by exposing video
+ overlay DirectDraw capabilities in the Guest Additions video
+ driver. The driver sends all overlay commands to the host
+ through a special communication tunnel implemented by
+ &product-name;. On the host side, OpenGL is then used to
+ implement color space transformation and scaling.
+ </para>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="seamlesswindows">
+
+ <title>Seamless Windows</title>
+
+ <para>
+ With the <emphasis>seamless windows</emphasis> feature of
+ &product-name;, you can have the windows that are displayed within
+ a virtual machine appear side by side next to the windows of your
+ host. This feature is supported for the following guest operating
+ systems, provided that the Guest Additions are installed:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Windows guests.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Supported Linux or Oracle Solaris guests running the X Window
+ System.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ After seamless windows are enabled, &product-name; suppresses the
+ display of the desktop background of your guest, allowing you to
+ run the windows of your guest operating system seamlessly next to
+ the windows of your host.
+ </para>
+
+ <figure id="fig-seamless-windows">
+ <title>Seamless Windows on a Host Desktop</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center" fileref="images/seamless.png" width="14cm" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ To enable seamless mode, after starting the virtual machine, press
+ the <emphasis role="bold">Host key + L</emphasis>. The Host key is
+ normally the right control key. This will enlarge the size of the
+ VM's display to the size of your host screen and mask out the
+ guest operating system's background. To disable seamless windows
+ and go back to the normal VM display, press the Host key + L
+ again.
+ </para>
+
+ </sect1>
+
+ <sect1 id="guestadd-guestprops">
+
+ <title>Guest Properties</title>
+
+ <para>
+ &product-name; enables requests of some properties from a running
+ guest, provided that the &product-name; Guest Additions are
+ installed and the VM is running. This provides the following
+ advantages:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ A number of predefined VM characteristics are automatically
+ maintained by &product-name; and can be retrieved on the host.
+ For example, to monitor VM performance and statistics.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Arbitrary string data can be exchanged between guest and host.
+ This works in both directions.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ To accomplish this, &product-name; establishes a private
+ communication channel between the &product-name; Guest Additions
+ and the host, and software on both sides can use this channel to
+ exchange string data for arbitrary purposes. Guest properties are
+ simply string keys to which a value is attached. They can be set,
+ or written to, by either the host and the guest. They can also be
+ read from both sides.
+ </para>
+
+ <para>
+ In addition to establishing the general mechanism of reading and
+ writing values, a set of predefined guest properties is
+ automatically maintained by the &product-name; Guest Additions to
+ allow for retrieving interesting guest data such as the guest's
+ exact operating system and service pack level, the installed
+ version of the Guest Additions, users that are currently logged
+ into the guest OS, network statistics and more. These predefined
+ properties are all prefixed with <literal>/VirtualBox/</literal>
+ and organized into a hierarchical tree of keys.
+ </para>
+
+ <para>
+ Some of this runtime information is shown when you select
+ <emphasis role="bold">Session Information Dialog</emphasis> from a
+ virtual machine's <emphasis role="bold">Machine</emphasis> menu.
+ </para>
+
+ <para>
+ A more flexible way to use this channel is with the
+ <command>VBoxManage guestproperty</command> command. See
+ <xref linkend="vboxmanage-guestproperty" />. For example, to have
+ <emphasis>all</emphasis> the available guest properties for a
+ given running VM listed with their respective values, use this
+ command:
+ </para>
+
+<screen>$ VBoxManage guestproperty enumerate "Windows Vista III"
+VirtualBox Command Line Management Interface Version <replaceable>version-number</replaceable>
+Copyright (C) 2005-2022 Oracle and/or its affiliates
+
+Name: /VirtualBox/GuestInfo/OS/Product, value: Windows Vista Business Edition,
+ timestamp: 1229098278843087000, flags:
+Name: /VirtualBox/GuestInfo/OS/Release, value: 6.0.6001,
+ timestamp: 1229098278950553000, flags:
+Name: /VirtualBox/GuestInfo/OS/ServicePack, value: 1,
+ timestamp: 1229098279122627000, flags:
+Name: /VirtualBox/GuestAdd/InstallDir,
+ value: C:/Program Files/Oracle/VirtualBox
+ Guest Additions, timestamp: 1229098279269739000, flags:
+Name: /VirtualBox/GuestAdd/Revision, value: 40720,
+ timestamp: 1229098279345664000, flags:
+Name: /VirtualBox/GuestAdd/Version, value: <replaceable>version-number</replaceable>,
+ timestamp: 1229098279479515000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxControl.exe, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279651731000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxHook.dll, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279804835000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxDisp.dll, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279880611000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxMRXNP.dll, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279882618000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxService.exe, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279883195000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxTray.exe, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279885027000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxGuest.sys, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279886838000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxMouse.sys, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279890600000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxSF.sys, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279893056000, flags:
+Name: /VirtualBox/GuestAdd/Components/VBoxVideo.sys, value: <replaceable>version-number</replaceable>r40720,
+ timestamp: 1229098279895767000, flags:
+Name: /VirtualBox/GuestInfo/OS/LoggedInUsers, value: 1,
+ timestamp: 1229099826317660000, flags:
+Name: /VirtualBox/GuestInfo/OS/NoLoggedInUsers, value: false,
+ timestamp: 1229098455580553000, flags:
+Name: /VirtualBox/GuestInfo/Net/Count, value: 1,
+ timestamp: 1229099826299785000, flags:
+Name: /VirtualBox/HostInfo/GUI/LanguageID, value: C,
+ timestamp: 1229098151272771000, flags:
+Name: /VirtualBox/GuestInfo/Net/0/V4/IP, value: 192.168.2.102,
+ timestamp: 1229099826300088000, flags:
+Name: /VirtualBox/GuestInfo/Net/0/V4/Broadcast, value: 255.255.255.255,
+ timestamp: 1229099826300220000, flags:
+Name: /VirtualBox/GuestInfo/Net/0/V4/Netmask, value: 255.255.255.0,
+ timestamp: 1229099826300350000, flags:
+Name: /VirtualBox/GuestInfo/Net/0/Status, value: Up,
+ timestamp: 1229099826300524000, flags:
+Name: /VirtualBox/GuestInfo/OS/LoggedInUsersList, value: username,
+ timestamp: 1229099826317386000, flags:</screen>
+
+ <para>
+ To query the value of a single property, use the
+ <command>get</command> subcommand as follows:
+ </para>
+
+<screen>$ VBoxManage guestproperty get "Windows Vista III" "/VirtualBox/GuestInfo/OS/Product"
+VirtualBox Command Line Management Interface Version <replaceable>version-number</replaceable>
+Copyright (C) 2005-2022 Oracle and/or its affiliates
+
+Value: Windows Vista Business Edition</screen>
+
+ <para>
+ To add or change guest properties from the guest, use the tool
+ <command>VBoxControl</command>. This tool is included in the Guest
+ Additions. When started from a Linux guest, this tool requires
+ root privileges for security reasons.
+ </para>
+
+<screen>$ sudo VBoxControl guestproperty enumerate
+VirtualBox Guest Additions Command Line Management Interface Version <replaceable>version-number</replaceable>
+Copyright (C) 2005-2022 Oracle and/or its affiliates
+
+Name: /VirtualBox/GuestInfo/OS/Release, value: 2.6.28-18-generic,
+ timestamp: 1265813265835667000, flags: &lt;NULL&gt;
+Name: /VirtualBox/GuestInfo/OS/Version, value: #59-Ubuntu SMP Thu Jan 28 01:23:03 UTC 2010,
+ timestamp: 1265813265836305000, flags: &lt;NULL&gt;
+ ...</screen>
+
+ <para>
+ For more complex needs, you can use the &product-name; programming
+ interfaces. See <xref linkend="VirtualBoxAPI" />.
+ </para>
+
+ <sect2 id="guestadd-guestprops-waits">
+
+ <title>Using Guest Properties to Wait on VM Events</title>
+
+ <para>
+ The properties <literal>/VirtualBox/HostInfo/VBoxVer</literal>,
+ <literal>/VirtualBox/HostInfo/VBoxVerExt</literal> or
+ <literal>/VirtualBox/HostInfo/VBoxRev</literal> can be waited on
+ to detect that the VM state was restored from saved state or
+ snapshot:
+ </para>
+
+<screen>$ VBoxControl guestproperty wait /VirtualBox/HostInfo/VBoxVer</screen>
+
+ <para>
+ Similarly the
+ <literal>/VirtualBox/HostInfo/ResumeCounter</literal> can be
+ used to detect that a VM was resumed from the paused state or
+ saved state.
+ </para>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="guestadd-gc-file-manager">
+
+ <title>Guest Control File Manager</title>
+
+ <para>
+ The Guest Control File Manager is a feature of the Guest Additions
+ that enables easy copying and moving of files between a guest and
+ the host system. Other file management operations provide support
+ to create new folders and to rename or delete files.
+ </para>
+
+ <para>
+ This feature is useful when the VM window of a guest is not
+ visible. For example, when the guest is running in headless mode.
+ </para>
+
+ <note>
+ <para>
+ To use the Guest Control File Manager, the guest must be
+ running. For powered-off guests, it is disabled automatically.
+ </para>
+ </note>
+
+ <figure id="fig-guest-control-fm">
+ <title>Guest Control File Manager</title>
+ <mediaobject>
+ <imageobject>
+ <imagedata align="center" fileref="images/guest-fm.png"
+ width="12cm" />
+ </imageobject>
+ </mediaobject>
+
+ </figure>
+
+ <para>
+ The Guest Control File Manager works by mounting the host file
+ system. Guest users must authenticate and create a guest session
+ before they can transfer files.
+ </para>
+
+ <sect2 id="guestadd-gc-file-manager-using">
+
+ <title>Using the Guest Control File Manager</title>
+
+ <para>
+ The following steps describe how to use the Guest Control File
+ Manager.
+ </para>
+
+ <orderedlist>
+
+ <listitem>
+ <para>
+ Open the Guest Control File Manager. Do either of the
+ following:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ In the guest VM, select
+ <emphasis role="bold">Machine</emphasis>,
+ <emphasis role="bold">File Manager</emphasis>.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ In &vbox-mgr;, click on the machine name. Click
+ <emphasis role="bold">File Manager</emphasis> in the
+ machine tools menu for the VM.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ The left pane shows the files on the host system.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Create a guest session.
+ </para>
+
+ <para>
+ At the bottom of the Guest Control File Manager, enter
+ authentication credentials for a user on the guest system.
+ </para>
+
+ <para>
+ Click <emphasis role="bold">Create Session</emphasis>.
+ </para>
+
+ <para>
+ The contents of the guest VM file system appears in the
+ right pane of the Guest Control File Manager.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Transfer files between the guest and the host system by
+ using the move and copy file transfer icons.
+ </para>
+
+ <para>
+ You can copy and move files from the guest to the host
+ system or from the host system to the guest.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Close the Guest Control File Manager.
+ </para>
+
+ <para>
+ Click <emphasis role="bold">Close</emphasis> to end the
+ guest session.
+ </para>
+ </listitem>
+
+ </orderedlist>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="guestadd-guestcontrol">
+
+ <title>Guest Control of Applications</title>
+
+ <para>
+ The Guest Additions enable starting of applications inside a guest
+ VM from the host system. This feature can be used to automate
+ deployment of software within the guest.
+ </para>
+
+ <para>
+ For this to work, the application needs to be installed on the
+ guest. No additional software needs to be installed on the host.
+ Additionally, text mode output to stdout and stderr can be shown
+ on the host for further processing. There are options to specify
+ user credentials and a timeout value, in milliseconds, to limit
+ the time the application is able to run.
+ </para>
+
+ <para>
+ The Guest Additions for Windows allow for automatic updating. This
+ applies for already installed Guest Additions versions. Also,
+ copying files from host to the guest as well as remotely creating
+ guest directories is available.
+ </para>
+
+ <para>
+ To use these features, use the &product-name; command line. See
+ <xref linkend="vboxmanage-guestcontrol" />.
+ </para>
+
+ </sect1>
+
+ <sect1 id="guestadd-memory-usage">
+
+ <title>Memory Overcommitment</title>
+
+ <para>
+ In server environments with many VMs, the Guest Additions can be
+ used to share physical host memory between several VMs. This
+ reduces the total amount of memory in use by the VMs. If memory
+ usage is the limiting factor and CPU resources are still
+ available, this can help with running more VMs on each host.
+ </para>
+
+ <sect2 id="guestadd-balloon">
+
+ <title>Memory Ballooning</title>
+
+ <para>
+ The Guest Additions can change the amount of host memory that a
+ VM uses, while the machine is running. Because of how this is
+ implemented, this feature is called <emphasis>memory
+ ballooning</emphasis>.
+ </para>
+
+ <note>
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ &product-name; supports memory ballooning only on 64-bit
+ hosts. It is not supported on macOS hosts.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Memory ballooning does not work well with large pages
+ enabled. To turn off large pages support for a VM, run
+ <command>VBoxManage modifyvm
+ <replaceable>vmname</replaceable> --large-pages
+ off</command>
+ </para>
+ </listitem>
+
+ </itemizedlist>
+ </note>
+
+ <para>
+ Normally, to change the amount of memory allocated to a virtual
+ machine, you have to shut down the virtual machine entirely and
+ modify its settings. With memory ballooning, memory that was
+ allocated for a virtual machine can be given to another virtual
+ machine without having to shut the machine down.
+ </para>
+
+ <para>
+ When memory ballooning is requested, the &product-name; Guest
+ Additions, which run inside the guest, allocate physical memory
+ from the guest operating system on the kernel level and lock
+ this memory down in the guest. This ensures that the guest will
+ not use that memory any longer. No guest applications can
+ allocate it, and the guest kernel will not use it either.
+ &product-name; can then reuse this memory and give it to another
+ virtual machine.
+ </para>
+
+ <para>
+ The memory made available through the ballooning mechanism is
+ only available for reuse by &product-name;. It is
+ <emphasis>not</emphasis> returned as free memory to the host.
+ Requesting balloon memory from a running guest will therefore
+ not increase the amount of free, unallocated memory on the host.
+ Effectively, memory ballooning is therefore a memory
+ overcommitment mechanism for multiple virtual machines while
+ they are running. This can be useful to temporarily start
+ another machine, or in more complicated environments, for
+ sophisticated memory management of many virtual machines that
+ may be running in parallel depending on how memory is used by
+ the guests.
+ </para>
+
+ <para>
+ At this time, memory ballooning is only supported through
+ <command>VBoxManage</command>. Use the following command to
+ increase or decrease the size of the memory balloon within a
+ running virtual machine that has Guest Additions installed:
+ </para>
+
+<screen>VBoxManage controlvm "VM name" guestmemoryballoon n</screen>
+
+ <para>
+ where <replaceable>VM name</replaceable> is the name or UUID of
+ the virtual machine in question and <replaceable>n</replaceable>
+ is the amount of memory to allocate from the guest in megabytes.
+ See <xref
+ linkend="vboxmanage-controlvm" />.
+ </para>
+
+ <para>
+ You can also set a default balloon that will automatically be
+ requested from the VM every time after it has started up with
+ the following command:
+ </para>
+
+<screen>VBoxManage modifyvm "VM name" --guest-memory-balloon n</screen>
+
+ <para>
+ By default, no balloon memory is allocated. This is a VM
+ setting, like other <command>modifyvm</command> settings, and
+ therefore can only be set while the machine is shut down. See
+ <xref
+ linkend="vboxmanage-modifyvm" />.
+ </para>
+
+ </sect2>
+
+ <sect2 id="guestadd-pagefusion">
+
+ <title>Page Fusion</title>
+
+ <para>
+ Whereas memory ballooning simply reduces the amount of RAM that
+ is available to a VM, Page Fusion works differently. It avoids
+ memory duplication between several similar running VMs.
+ </para>
+
+ <para>
+ In a server environment running several similar VMs on the same
+ host, lots of memory pages are identical. For example, if the
+ VMs are using identical operating systems. &product-name;'s Page
+ Fusion technology can efficiently identify these identical
+ memory pages and share them between multiple VMs.
+ </para>
+
+ <note>
+ <para>
+ &product-name; supports Page Fusion only on 64-bit hosts, and
+ it is not supported on macOS hosts. Page Fusion currently
+ works only with Windows 2000 and later guests.
+ </para>
+ </note>
+
+ <para>
+ The more similar the VMs on a given host are, the more
+ efficiently Page Fusion can reduce the amount of host memory
+ that is in use. It therefore works best if all VMs on a host run
+ identical operating systems. Instead of having a complete copy
+ of each operating system in each VM, Page Fusion identifies the
+ identical memory pages in use by these operating systems and
+ eliminates the duplicates, sharing host memory between several
+ machines. This is called <emphasis>deduplication</emphasis>. If
+ a VM tries to modify a page that has been shared with other VMs,
+ a new page is allocated again for that VM with a copy of the
+ shared page. This is called <emphasis>copy on write</emphasis>.
+ All this is fully transparent to the virtual machine.
+ </para>
+
+ <para>
+ You may be familiar with this kind of memory overcommitment from
+ other hypervisor products, which call this feature
+ <emphasis>page sharing</emphasis> or <emphasis>same page
+ merging</emphasis>. However, Page Fusion differs significantly
+ from those other solutions, whose approaches have several
+ drawbacks:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ Traditional hypervisors scan <emphasis>all</emphasis> guest
+ memory and compute checksums, also called hashes, for every
+ single memory page. Then, they look for pages with identical
+ hashes and compare the entire content of those pages. If two
+ pages produce the same hash, it is very likely that the
+ pages are identical in content. This process can take rather
+ long, especially if the system is not idling. As a result,
+ the additional memory only becomes available after a
+ significant amount of time, such as hours or sometimes days.
+ Even worse, this kind of page sharing algorithm generally
+ consumes significant CPU resources and increases the
+ virtualization overhead by 10 to 20%.
+ </para>
+
+ <para>
+ Page Fusion in &product-name; uses logic in the
+ &product-name; Guest Additions to quickly identify memory
+ cells that are most likely identical across VMs. It can
+ therefore achieve most of the possible savings of page
+ sharing almost immediately and with almost no overhead.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Page Fusion is also much less likely to be confused by
+ identical memory that it will eliminate, just to learn
+ seconds later that the memory will now change and having to
+ perform a highly expensive and often service-disrupting
+ reallocation.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <para>
+ At this time, Page Fusion can only be controlled with
+ <command>VBoxManage</command>, and only while a VM is shut down.
+ To enable Page Fusion for a VM, use the following command:
+ </para>
+
+<screen>VBoxManage modifyvm "VM name" --page-fusion on</screen>
+
+ <para>
+ You can observe Page Fusion operation using some metrics.
+ <literal>RAM/VMM/Shared</literal> shows the total amount of
+ fused pages, whereas the per-VM metric
+ <literal>Guest/RAM/Usage/Shared</literal> will return the amount
+ of fused memory for a given VM. See
+ <xref linkend="vboxmanage-metrics" /> for information on how to
+ query metrics.
+ </para>
+
+ <note>
+ <para>
+ Enabling Page Fusion might indirectly increase the chances for
+ malicious guests to successfully attack other VMs running on
+ the same host. See <xref linkend="pot-insecure"/>.
+ </para>
+ </note>
+
+ </sect2>
+
+ </sect1>
+
+ <sect1 id="guestadd-resizing">
+
+ <title>Controlling Virtual Monitor Topology</title>
+
+ <sect2 id="guestadd-resizing-linux">
+
+ <title>X11/Wayland Desktop Environments</title>
+
+ <para>
+ The Guest Additions provide services for controlling the guest
+ system's monitor topology. Monitor topology means the resolution
+ of each virtual monitor and its state (disabled/enabled). The
+ resolution of a virtual monitor can be modified from the host
+ side either by resizing the window that hosts the virtual
+ monitor, by using the <emphasis role="bold">View</emphasis> menu
+ or the <command>VBoxManage controlvm
+ <replaceable>vmname</replaceable> setscreenlayout</command>
+ command. On guest operating systems with X11/Wayland desktops
+ this is put into effect by either of the following two services:
+ </para>
+
+<screen>
+ VBoxClient --vmsvga
+ VBoxDRMClient
+ </screen>
+
+ <para>
+ The following are some details about guest screen resolution
+ control functionality:
+ </para>
+
+ <itemizedlist>
+
+ <listitem>
+ <para>
+ On X11/Wayland desktops the resizing service is started
+ during desktop session initialization, that is desktop
+ login. On X11 desktops <code>VBoxClient --vmsvga</code>
+ handles screen topology through the RandR extension. On
+ Wayland clients <code>VBoxDRMClient</code> is used. The
+ decision is made automatically at each desktop session
+ start.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ On 32-bit guest operating systems
+ <command>VBoxDRMClient</command> is always used, in order to
+ work around bugs.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Since the monitor topology control services are initialized
+ during the desktop session start, it is impossible to
+ control the monitor resolution of display managers such as
+ GDM or LightDM. This default behavior can be changed by
+ setting the guest property
+ <literal>/VirtualBox/GuestAdd/DRMResize</literal> of the
+ virtual machine to any value. See
+ <xref linkend="guestadd-guestprops" /> for details of how to
+ update guest properties. When this guest property is set
+ then <command>VBoxDRMClient</command> is started during the
+ guest OS boot and stays active all the time, for both the
+ display manager login screen and the desktop session.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+
+ <sect3 id="guestadd-resizing-linux-limitations">
+
+ <title>Known Limitations</title>
+
+ <para>
+ <command>VBoxDRMClient</command> is not able to handle
+ arbitrary guest monitor topologies. Specifically, disabling a
+ guest monitor that is not the last one invalidates the monitor
+ topology due to limitations in the
+ <literal>vmwgfx.ko</literal> Linux kernel module. For example,
+ when the guest is configured to have four monitors it is not
+ recommended to disable the second or third monitor.
+ </para>
+
+ </sect3>
+
+ </sect2>
+
+ </sect1>
+
+</chapter>