| 1 | <?xml version="1.0" encoding="UTF-8"?>
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| 2 | <!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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| 3 | "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
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| 4 | <chapter id="KnownIssues">
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| 5 | <title>Known limitations</title>
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| 6 | <sect1 id="ExperimentalFeatures">
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| 7 | <title>Experimental Features</title>
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| 8 | <para>Some VirtualBox features are labeled as experimental. Such
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| 9 | features are provided on an "as-is" basis and are not formally
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| 10 | supported. However, feedback and suggestions about such features are
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| 11 | welcome. A comprehensive list of experimental features follows:</para>
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| 12 | <itemizedlist>
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| 13 | <listitem>
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| 14 | <para>Hardware 3D acceleration support for Windows, Linux, and Solaris
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| 15 | guests</para>
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| 16 | </listitem>
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| 17 | <listitem>
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| 18 | <para>Hardware 2D video playback acceleration support for Windows
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| 19 | guests</para>
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| 20 | </listitem>
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| 21 | <listitem>
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| 22 | <para>PCI pass-through (Linux hosts only)</para>
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| 23 | </listitem>
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| 24 | <listitem>
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| 25 | <para>Mac OS X guests (Mac hosts only)</para>
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| 26 | </listitem>
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| 27 | <listitem>
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| 28 | <para>ICH9 chipset emulation</para>
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| 29 | </listitem>
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| 30 | <listitem>
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| 31 | <para>EFI firmware</para>
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| 32 | </listitem>
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| 33 | <listitem>
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| 34 | <para>Host CD/DVD drive pass-through</para>
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| 35 | </listitem>
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| 36 | <listitem>
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| 37 | <para>Support of iSCSI via internal networking</para>
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| 38 | </listitem>
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| 39 | </itemizedlist>
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| 40 | </sect1>
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| 41 | <sect1 id="KnownProblems">
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| 42 | <title>Known Issues</title>
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| 43 | <para>The following section describes known problems with VirtualBox
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| 44 | @VBOX_VERSION_STRING@. Unless marked otherwise, these issues are planned to
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| 45 | be fixed in later releases.</para>
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| 46 |
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| 47 | <itemizedlist>
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| 48 | <listitem>
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| 49 | <para>The following <emphasis role="bold">Guest SMP (multiprocessor)
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| 50 | limitations</emphasis> exist:<itemizedlist>
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| 51 | <listitem>
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| 52 | <para><emphasis role="bold">Poor performance</emphasis> with
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| 53 | 32-bit guests on AMD CPUs. This affects mainly Windows and Solaris
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| 54 | guests, but possibly also some Linux kernel revisions. Partially
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| 55 | solved in 3.0.6 for 32 bits Windows NT, 2000, XP and 2003 guests.
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| 56 | Requires 3.0.6 or higher Guest Additions to be installed.</para>
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| 57 | </listitem>
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| 58 |
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| 59 | <listitem>
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| 60 | <para><emphasis role="bold">Poor performance</emphasis> with
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| 61 | 32-bit guests on certain Intel CPU models that do not include
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| 62 | virtual APIC hardware optimization support. This affects mainly
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| 63 | Windows and Solaris guests, but possibly also some Linux kernel
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| 64 | revisions. Partially solved in 3.0.12 for 32 bits Windows NT,
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| 65 | 2000, XP and 2003 guests. Requires 3.0.12 or higher Guest
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| 66 | Additions to be installed.</para>
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| 67 | </listitem>
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| 68 | </itemizedlist></para>
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| 69 | </listitem>
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| 70 |
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| 71 | <listitem>
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| 72 | <para><emphasis role="bold">NX (no execute, data execution
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| 73 | prevention)</emphasis> only works for guests running on 64-bit hosts
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| 74 | or guests running on 32-bit hosts with PAE enabled and requires that
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| 75 | hardware virtualization be enabled.</para>
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| 76 | </listitem>
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| 77 |
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| 78 | <listitem>
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| 79 | <para>For <emphasis role="bold">basic Direct3D support in Windows
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| 80 | guests</emphasis> to work, the Guest Additions must be installed in
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| 81 | Windows "safe mode". Press F8 when the Windows guest is booting and
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| 82 | select "Safe mode", then install the Guest Additions. Otherwise Windows'
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| 83 | file protection mechanism will interfere with the replacement DLLs
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| 84 | installed by VirtualBox and keep restoring the original Windows system
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| 85 | DLLs. <note>
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| 86 | <para>This does <emphasis role="bold">not</emphasis> apply to the
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| 87 | WDDM Direct3D video driver available for Vista and Windows 7 guests
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| 88 | shipped with VirtualBox 4.1.</para>
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| 89 | </note></para>
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| 90 | </listitem>
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| 91 |
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| 92 | <listitem>
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| 93 | <para><emphasis role="bold">Guest control.</emphasis> On Windows guests,
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| 94 | a process lauched via the guest control execute support will not be able
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| 95 | to display a graphical user interface <emphasis>unless</emphasis> the
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| 96 | user account under which it is running is currently logged in and has a
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| 97 | desktop session.</para>
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| 98 |
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| 99 | <para>Also, to use accounts without or with an empty password, the
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| 100 | guest's group policy must be changed. To do so, open the group policy
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| 101 | editor on the command line by typing
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| 102 | <computeroutput>gpedit.msc</computeroutput>, open the key
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| 103 | <emphasis>Computer Configuration\Windows Settings\Security
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| 104 | Settings\Local Policies\Security Options</emphasis> and change the value
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| 105 | of <emphasis>Accounts: Limit local account use of blank passwords to
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| 106 | console logon only</emphasis> to <emphasis>Disabled</emphasis>.</para>
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| 107 | </listitem>
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| 108 |
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| 109 | <listitem>
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| 110 | <para><emphasis role="bold">Compacting virtual disk images is limited to
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| 111 | VDI files.</emphasis> The <code>VBoxManage modifyhd --compact</code>
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| 112 | command is currently only implemented for VDI files. At the moment the
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| 113 | only way to optimize the size of a virtual disk images in other formats
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| 114 | (VMDK, VHD) is to clone the image and then use the cloned image in the
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| 115 | VM configuration.</para>
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| 116 | </listitem>
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| 117 |
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| 118 | <listitem>
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| 119 | <para><emphasis role="bold">OVF import/export:</emphasis><itemizedlist>
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| 120 | <listitem>
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| 121 | <para>OVF localization (multiple languages in one OVF file) is not
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| 122 | yet supported.</para>
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| 123 | </listitem>
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| 124 |
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| 125 | <listitem>
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| 126 | <para>Some OVF sections like StartupSection,
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| 127 | DeploymentOptionSection and InstallSection are ignored.</para>
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| 128 | </listitem>
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| 129 |
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| 130 | <listitem>
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| 131 | <para>OVF environment documents, including their property sections
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| 132 | and appliance configuration with ISO images, are not yet
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| 133 | supported.</para>
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| 134 | </listitem>
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| 135 |
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| 136 | <listitem>
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| 137 | <para>Remote files via HTTP or other mechanisms are not yet
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| 138 | supported.</para>
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| 139 | </listitem>
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| 140 | </itemizedlist></para>
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| 141 | </listitem>
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| 142 |
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| 143 | <listitem>
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| 144 | <para>Neither <emphasis role="bold">scale mode</emphasis> nor <emphasis
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| 145 | role="bold">seamless mode</emphasis> work correctly with guests using
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| 146 | OpenGL 3D features (such as with compiz-enabled window managers).</para>
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| 147 | </listitem>
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| 148 |
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| 149 | <listitem>
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| 150 | <para>The RDP server in the VirtualBox extension pack supports only
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| 151 | audio streams in format 22.05kHz stereo 16 bit. If the RDP client
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| 152 | requests any other audio format there will be no audio.</para>
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| 153 | </listitem>
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| 154 |
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| 155 | <listitem>
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| 156 | <para>Preserving the aspect ratio in scale mode works only on Windows
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| 157 | hosts and on Mac OS X hosts.</para>
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| 158 | </listitem>
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| 159 |
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| 160 | <listitem>
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| 161 | <para>On <emphasis role="bold">Mac OS X hosts,</emphasis> the following
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| 162 | features are not yet implemented:</para>
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| 163 |
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| 164 | <para><itemizedlist>
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| 165 | <listitem>
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| 166 | <para>Numlock emulation</para>
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| 167 | </listitem>
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| 168 |
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| 169 | <listitem>
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| 170 | <para>CPU frequency metric</para>
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| 171 | </listitem>
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| 172 |
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| 173 | <listitem>
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| 174 | <para>Memory ballooning</para>
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| 175 | </listitem>
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| 176 | </itemizedlist></para>
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| 177 | </listitem>
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| 178 |
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| 179 | <listitem>
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| 180 | <para><emphasis role="bold">Mac OS X guests:</emphasis>
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| 181 | <itemizedlist>
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| 182 | <listitem>
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| 183 | <para>Mac OS X guests can only run on a certain host hardware.
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| 184 | For details about license and host hardware limitations, please
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| 185 | see <xref linkend="intro-macosxguests" /> and check the Apple
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| 186 | software license conditions.</para>
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| 187 | </listitem>
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| 188 |
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| 189 | <listitem>
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| 190 | <para>VirtualBox does not provide Guest Additions for Mac OS X
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| 191 | at this time.</para>
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| 192 | </listitem>
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| 193 |
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| 194 | <listitem>
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| 195 | <para>The graphics resolution currently defaults to 1024x768 as
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| 196 | Mac OS X falls back to the built-in EFI display support. See
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| 197 | <xref linkend="efividmode" /> for more information on how to
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| 198 | change EFI video modes.</para>
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| 199 | </listitem>
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| 200 |
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| 201 | <listitem>
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| 202 | <para>Mac OS X guests only work with one CPU assigned to the
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| 203 | VM. Support for SMP will be provided in a future release.</para>
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| 204 | </listitem>
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| 205 |
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| 206 | <listitem>
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| 207 | <para>Depending on your system and version of Mac OS X, you
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| 208 | might experience guest hangs after some time. This can be fixed
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| 209 | by turning off energy saving (set timeout to "Never") in the
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| 210 | system preferences.</para>
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| 211 | </listitem>
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| 212 |
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| 213 | <listitem>
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| 214 | <para>By default, the VirtualBox EFI enables debug output of the
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| 215 | Mac OS X kernel to help you diagnose boot problems. Note that
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| 216 | there is a lot of output and not all errors are fatal (they
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| 217 | would also show on your physical Mac). You can turn off these
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| 218 | messages by issuing this command:<screen>VBoxManage setextradata "VM name" "VBoxInternal2/EfiBootArgs" " "</screen>To
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| 219 | revert to the previous behavior, use:<screen>VBoxManage setextradata "VM name" "VBoxInternal2/EfiBootArgs" ""</screen></para>
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| 220 | </listitem>
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| 221 |
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| 222 | <listitem>
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| 223 | <para>It is currently not possible to start a Mac OS X guest in safe mode by specifying "-x" option
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| 224 | in "VBoxInternal2/EfiBootArgs" extradata.</para>
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| 225 | </listitem>
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| 226 | </itemizedlist></para>
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| 227 | </listitem>
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| 228 |
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| 229 | <listitem>
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| 230 | <para><emphasis role="bold">Solaris hosts:</emphasis> <itemizedlist>
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| 231 | <listitem>
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| 232 | <para>There is no support for USB devices connected to Solaris 10
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| 233 | hosts.</para>
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| 234 | </listitem>
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| 235 |
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| 236 | <listitem>
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| 237 | <para>USB support on Solaris hosts requires Solaris 11 version
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| 238 | snv_124 or higher. Webcams and other isochronous devices are known
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| 239 | to have poor performance.</para>
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| 240 | </listitem>
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| 241 |
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| 242 | <listitem>
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| 243 | <para>Host Webcam passthrough is restricted to 640x480 frames at
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| 244 | 20 frames per second due to limitations in the Solaris V4L2 API.
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| 245 | This may be addressed in a future Solaris release.</para>
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| 246 | </listitem>
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| 247 |
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| 248 | <listitem>
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| 249 | <para>No ACPI information (battery status, power source) is
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| 250 | reported to the guest.</para>
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| 251 | </listitem>
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| 252 |
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| 253 | <listitem>
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| 254 | <para>No support for using wireless adapters with bridged
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| 255 | networking.</para>
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| 256 | </listitem>
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| 257 |
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| 258 | <listitem>
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| 259 | <para>Crossbow-based bridged networking on Solaris 11 hosts does
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| 260 | not work directly with aggregate links. However, you can manually
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| 261 | create a VNIC (using <computeroutput>dladm</computeroutput>) over
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| 262 | the aggregate link and use that with a VM. This limitation does
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| 263 | not exist in Solaris 11u1 build 17 and newer.</para>
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| 264 | </listitem>
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| 265 | </itemizedlist></para>
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| 266 | </listitem>
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| 267 |
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| 268 | <listitem>
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| 269 | <para><emphasis role="bold">Guest Additions of version 4.1, 4.1.2 and 4.1.4 for Windows</emphasis>
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| 270 | Thus VirtualBox WDDM Video driver may be installed and kept in guest system
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| 271 | if Guest additions uninstallation is performed.
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| 272 | This is caused by a bug in Guest Additions uninstaller.
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| 273 | <note>
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| 274 | <para>This does <emphasis role="bold">not</emphasis> apply to Guest Additions update,
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| 275 | i.e. installing a one version of Guest Additions on top of another works correctly.</para>
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| 276 | </note>
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| 277 | To solve this problem, one should uninstall the VirtualBox WDDM Video driver manually.
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| 278 | To do that open Device Manager, and check whether the Display Adapter is named
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| 279 | "VirtualBox Graphics Adapter ..". If no - there is nothing to be done. If yes - right-click
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| 280 | the VirtualBox Graphics Adapter in Device Manager, select "Uninstall", check "Delete the driver software for this device"
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| 281 | and click "OK". Once uninstallation is done - in Device Manager go to menu "Action" and select
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| 282 | "Scan for hardware changes" to make the propper (Windows default) driver be picked up for the Graphics adapter.
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| 283 | </para>
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| 284 | </listitem>
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| 285 |
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| 286 | <listitem>
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| 287 | <para>Neither <emphasis>virtio</emphasis> nor <emphasis>Intel PRO/1000
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| 288 | </emphasis> drivers for <emphasis role="bold">Windows XP guests
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| 289 | </emphasis> support segmentation offloading. Therefore
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| 290 | Windows XP guests have slower transmission rates comparing to other
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| 291 | guest types. Refer to MS Knowledge base article 842264 for additional
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| 292 | information.</para>
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| 293 | </listitem>
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| 294 |
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| 295 | <listitem>
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| 296 | <para><emphasis role="bold">Guest Additions for OS/2.</emphasis> Shared
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| 297 | folders are not yet supported with OS/2 guests. In addition, seamless
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| 298 | windows and automatic guest resizing will probably never be implemented
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| 299 | due to inherent limitations of the OS/2 graphics system.</para>
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| 300 | </listitem>
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| 301 | </itemizedlist>
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| 302 | </sect1>
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| 303 | </chapter>
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