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<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
<topic xml:lang="en-us" id="KnownProblems">
<title>Known Issues</title>
<body>
<p>The following section describes known problems with this release of <ph
conkeyref="vbox-conkeyref-phrases/product-name"/>. Unless marked otherwise, these issues are planned to be fixed
in later releases. </p>
<ul>
<li>Saved states and online snapshots created on Arm VMs in <ph conkeyref="vbox-conkeyref-phrases/product-name"/> 7.1 will not be usable in later releases. Saved states within 7.1 are working as expected.</li>
<li>Internal networking on macOS hosts doesn't work between VMs run by different users.</li>
<li>
<p>Poor performance when using <ph conkeyref="vbox-conkeyref-phrases/product-name"/> and <b outputclass="bold"
>Hyper-V</b> on the same host. To fix this, certain Windows features like "Hyper-V Platform", "Virtual
Machine Platform" and "Windows Hypervisor Platform" must be turned off, followed by a host reboot. </p>
<p>On newer Windows versions, enabling the device security features Core Isolation or Memory Integrity will use Hyper-V, even if you had previously turned it off.</p>
<p>Additionally, the Microsoft Device Guard and Credential Guard hardware readiness tool might have to be used
in order to turn off more features. For example, by running the following command: </p>
<pre xml:space="preserve">.\DG_Readiness_Tool_vX.X.ps1 -Disable -AutoReboot</pre>
<note>
<p>Disabling Device Guard and Credential Guard features will have an impact on the overall security of the
host. Please contact your Administrator beforehand regarding this. </p>
</note>
</li>
<li>
<p>
The following <b outputclass="bold">Guest SMP (multiprocessor)
limitations</b> exist:
</p>
<ul>
<li>
<p><b outputclass="bold">Poor performance</b> with
32-bit guests on AMD CPUs. This affects mainly Windows and
Oracle Solaris guests, but possibly also some Linux kernel
revisions. Partially solved for 32-bit Windows NT, 2000,
XP, and 2003 guests. Requires the Guest Additions to be
installed.
</p>
</li>
<li>
<p><b outputclass="bold">Poor performance</b> with
32-bit guests on certain Intel CPU models that do not
include virtual APIC hardware optimization support. This
affects mainly Windows and Oracle Solaris guests, but
possibly also some Linux kernel revisions. Partially
solved for 32-bit Windows NT, 2000, XP, and 2003 guests.
Requires the Guest Additions to be installed.
</p>
</li>
</ul>
</li>
<li>
<p><b outputclass="bold">NX (no execute, data execution
prevention)</b> only works for guests running on 64-bit
hosts and requires that hardware virtualization be enabled.
</p>
</li>
<li>
<p><b outputclass="bold">Guest control.</b> On Windows
guests, a process started using the guest control execute
support will not be able to display a graphical user interface
<i>unless</i> the user account under which it is
running is currently logged in and has a desktop session.
</p>
<p>Also, to use accounts without or with an empty password, the guest's group policy must be changed. To do so,
open the group policy editor on the command line by typing <userinput>gpedit.msc</userinput>, open the key
<codeph>Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options</codeph>
and change the value of <codeph>Accounts: Limit local account use of blank passwords to console logon
only</codeph> to Disabled. </p>
</li>
<li>
<p><b outputclass="bold">Compacting virtual disk images is
limited to VDI files.</b> The <userinput>VBoxManage
modifymedium --compact</userinput> command is currently only
implemented for VDI files. At the moment the only way to
optimize the size of a virtual disk images in other formats,
such as VMDK or VHD, is to clone the image and then use the
cloned image in the VM configuration.
</p>
</li>
<li>
<p><b outputclass="bold">OVF import/export:</b>
</p>
<ul>
<li>
<p>OVF localization, with multiple languages in a single OVF file, is not yet supported. </p>
</li>
<li>
<p>Some OVF sections like StartupSection, DeploymentOptionSection, and InstallSection are ignored. </p>
</li>
<li>
<p>OVF environment documents, including their property sections and appliance configuration with ISO images,
are not yet supported. </p>
</li>
<li>
<p>Remote files using HTTP or other mechanisms are not yet supported. </p>
</li>
</ul>
</li>
<li>
<p>The RDP server in the <ph conkeyref="vbox-conkeyref-phrases/product-name"/> extension pack supports only
audio streams in format 22.05kHz stereo 16-bit. If the RDP client requests any other audio format there will
be no audio. </p>
</li>
<li>
<p>Preserving the aspect ratio in scale mode works only on Windows hosts and on macOS hosts. </p>
</li>
<li>
<p>On <b outputclass="bold">macOS hosts</b>, the following features are not yet implemented: </p>
<ul>
<li>
<p>
Numlock emulation
</p>
</li>
<li>
<p>
CPU frequency metric
</p>
</li>
<li>
<p>
Memory ballooning
</p>
</li>
</ul>
</li>
<li>
<p><b outputclass="bold">macOS/Arm 64 (Apple silicon) host package</b>
<ul id="ul_ddr_kzn_hcc">
<li>
<p>x86-based guest operating systems will not run.</p>
</li>
<li>
<p>Arm(AArch64) guests only. Arm 32 is not supported at present.</p>
</li>
<li>
<p>Arm hosts have limitations with sound, storage, graphics, guest additions and unattended
installation.</p>
</li>
</ul></p>
</li>
<li>
<p><b outputclass="bold">Mac OS X guests:</b>
</p>
<ul>
<li>
<p>Mac OS X guests can only run on a certain host hardware. For details about license and host hardware
limitations. See <xref href="intro-macosxguests.dita">Mac OS X Guests</xref> and check the Apple software
license conditions. </p>
</li>
<li>
<p><ph conkeyref="vbox-conkeyref-phrases/product-name"/> does not provide Guest Additions for Mac OS X at
this time. </p>
</li>
<li>
<p>The graphics resolution currently defaults to 1024x768 as Mac OS X falls back to the built-in EFI display
support. See <xref href="efividmode.dita">Video Modes in EFI</xref> for more information on how to change
EFI video modes. </p>
</li>
<li>
<p>Mac OS X guests only work with one CPU assigned to the VM. Support for SMP will be provided in a future
release. </p>
</li>
<li>
<p>Depending on your system and version of Mac OS X, you might experience guest hangs after some time. This
can be fixed by turning off energy saving. Set the timeout to "Never" in the system preferences. </p>
</li>
<li>
<p>By default, the <ph conkeyref="vbox-conkeyref-phrases/product-name"/> EFI enables debug output of the Mac
OS X kernel to help you diagnose boot problems. Note that there is a lot of output and not all errors are
fatal. They would also show when using a physical Apple Macintosh computer. You can turn off these
messages by using the following command: </p>
<pre xml:space="preserve">$ VBoxManage setextradata <varname>VM-name</varname> "VBoxInternal2/EfiBootArgs" " "</pre>
<p>
To revert to the previous behavior, use the following
command:
</p>
<pre xml:space="preserve">$ VBoxManage setextradata <varname>VM-name</varname> "VBoxInternal2/EfiBootArgs" ""</pre>
</li>
<li>
<p>It is currently not possible to start a Mac OS X guest in safe mode by specifying the <codeph>-x</codeph>
option in <codeph>VBoxInternal2/EfiBootArgs</codeph> extradata. </p>
</li>
</ul>
</li>
<li>
<p>
<b outputclass="bold">Oracle Solaris hosts:</b>
</p>
<ul>
<li>
<p>USB support on Oracle Solaris hosts requires Oracle Solaris 11 FCS or later. Webcams and other isochronous devices are known to have poor performance. </p>
</li>
<li>
<p>Host Webcam passthrough is restricted to 640x480 frames at 20 frames per second due to limitations in the
Oracle Solaris V4L2 API. This may be addressed in a future Oracle Solaris release. </p>
</li>
<li>
<p>No ACPI information, such as battery status or power source, is reported to the guest. </p>
</li>
<li>
<p>No support for using wireless adapters with bridged networking. </p>
</li>
<li>
<p>Crossbow-based bridged networking on Oracle Solaris 11 hosts does not work directly with aggregate links. However, you can use <userinput>dladm</userinput> to manually create a VNIC over the aggregate link and use that with a VM. This limitation does not exist in Oracle Solaris 11 update 1 (11.1) and later. </p>
</li>
</ul>
</li>
<li>
<p>Neither virtio nor Intel PRO/1000 drivers for <b outputclass="bold">Windows XP guests</b> support
segmentation offloading. Therefore Windows XP guests have slower transmission rates comparing to other guest
types. Refer to MS Knowledge base article 842264 for additional information. </p>
</li>
<li>
<p><b outputclass="bold">Guest Additions for OS/2.</b>
Seamless windows and automatic guest resizing will probably
never be implemented due to inherent limitations of the OS/2
graphics system.
</p>
</li>
<li>
<p>Some guest operating systems predating ATAPI CD-ROMs may exhibit long delays or entirely fail to boot in
certain configurations. This is most likely to happen when an IDE/ATAPI CD-ROM exists alone on a primary or
secondary IDE channel. </p>
<p>Affected operating systems are MS OS/2 1.21: fails to boot with an error message referencing COUNTRY.SYS and
MS OS/2 1.3: long boot delays. To avoid such problems, disable the emulated IDE/ATAPI CD-ROM. The guest OS
cannot use this device, anyway. </p>
</li>
</ul>
</body>
</topic>
|
