VirtualBox

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1<?xml version="1.0" encoding="UTF-8"?>
2<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"[
4<!ENTITY % all.entities SYSTEM "all-entities.ent">
5%all.entities;
6]>
7<chapter id="KnownIssues">
8
9 <title>Known Limitations</title>
10
11 <sect1 id="ExperimentalFeatures">
12
13 <title>Experimental Features</title>
14
15 <para>
16 Some &product-name; features are labeled as experimental. Such
17 features are provided on an "as-is" basis and are not formally
18 supported. However, feedback and suggestions about such features
19 are welcome. A comprehensive list of experimental features is as
20 follows:
21 </para>
22
23 <itemizedlist>
24
25 <listitem>
26 <para>
27 Hardware 3D acceleration support for Windows, Linux, and
28 Oracle Solaris guests
29 </para>
30 </listitem>
31
32<!-- <listitem>
33 <para>
34 PCI passthrough (Linux hosts only)
35 </para>
36 </listitem>-->
37
38 <listitem>
39 <para>
40 Mac OS X guests (Mac OS X hosts only)
41 </para>
42 </listitem>
43
44 <listitem>
45 <para>
46 ICH9 chipset emulation
47 </para>
48 </listitem>
49
50 <listitem>
51 <para>
52 EFI firmware
53 </para>
54 </listitem>
55
56 <listitem>
57 <para>
58 Host CD/DVD drive passthrough
59 </para>
60 </listitem>
61
62 <listitem>
63 <para>
64 Support of iSCSI using internal networking
65 </para>
66 </listitem>
67
68 <listitem>
69 <para>
70 Using &product-name; and Hyper-V on the same host
71 </para>
72 </listitem>
73
74 </itemizedlist>
75
76 </sect1>
77
78 <sect1 id="KnownProblems">
79
80 <title>Known Issues</title>
81
82 <para>
83 The following section describes known problems with this release
84 of &product-name;. Unless marked otherwise, these issues are
85 planned to be fixed in later releases.
86 </para>
87
88 <itemizedlist>
89
90 <listitem>
91 <para>
92 Poor performance when using &product-name; and <emphasis
93 role="bold">Hyper-V</emphasis> on the same host. To fix this, certain
94 Windows features like "Hyper-V Platform", "Virtual Machine Platform" and
95 "Windows Hypervisor Platform" have to be turned off, followed by a host
96 reboot.
97 </para>
98 <para>
99 Additionally, the "Microsoft Device Guard and Credential Guard hardware
100 readiness tool" might be used in order to turn off more features,
101 for example with <screen>.\DG_Readiness_Tool_vX.X.ps1 -Disable -AutoReboot</screen>
102 <note>
103 <para>
104 Disabling Device Guard and Credential Guard features will have an
105 impact on the overall security of the host. Please contact your Administrator
106 beforehand regarding this.
107 </para>
108 </note>
109 </para>
110 </listitem>
111
112 <listitem>
113 <para>
114 The following <emphasis role="bold">Guest SMP (multiprocessor)
115 limitations</emphasis> exist:
116 </para>
117
118 <itemizedlist>
119
120 <listitem>
121 <para>
122 <emphasis role="bold">Poor performance</emphasis> with
123 32-bit guests on AMD CPUs. This affects mainly Windows and
124 Oracle Solaris guests, but possibly also some Linux kernel
125 revisions. Partially solved for 32-bit Windows NT, 2000,
126 XP, and 2003 guests. Requires the Guest Additions to be
127 installed.
128 </para>
129 </listitem>
130
131 <listitem>
132 <para>
133 <emphasis role="bold">Poor performance</emphasis> with
134 32-bit guests on certain Intel CPU models that do not
135 include virtual APIC hardware optimization support. This
136 affects mainly Windows and Oracle Solaris guests, but
137 possibly also some Linux kernel revisions. Partially
138 solved for 32-bit Windows NT, 2000, XP, and 2003 guests.
139 Requires the Guest Additions to be installed.
140 </para>
141 </listitem>
142
143 </itemizedlist>
144 </listitem>
145
146 <listitem>
147 <para>
148 <emphasis role="bold">NX (no execute, data execution
149 prevention)</emphasis> only works for guests running on 64-bit
150 hosts and requires that hardware virtualization be enabled.
151 </para>
152 </listitem>
153
154 <listitem>
155 <para>
156 <emphasis role="bold">Guest control.</emphasis> On Windows
157 guests, a process started using the guest control execute
158 support will not be able to display a graphical user interface
159 <emphasis>unless</emphasis> the user account under which it is
160 running is currently logged in and has a desktop session.
161 </para>
162
163 <para>
164 Also, to use accounts without or with an empty password, the
165 guest's group policy must be changed. To do so, open the group
166 policy editor on the command line by typing
167 <command>gpedit.msc</command>, open the key <literal>Computer
168 Configuration\Windows Settings\Security Settings\Local
169 Policies\Security Options</literal> and change the value of
170 <literal>Accounts: Limit local account use of blank passwords
171 to console logon only</literal> to Disabled.
172 </para>
173 </listitem>
174
175 <listitem>
176 <para>
177 <emphasis role="bold">Compacting virtual disk images is
178 limited to VDI files.</emphasis> The <command>VBoxManage
179 modifymedium --compact</command> command is currently only
180 implemented for VDI files. At the moment the only way to
181 optimize the size of a virtual disk images in other formats,
182 such as VMDK or VHD, is to clone the image and then use the
183 cloned image in the VM configuration.
184 </para>
185 </listitem>
186
187 <listitem>
188 <para>
189 <emphasis role="bold">OVF import/export:</emphasis>
190 </para>
191
192 <itemizedlist>
193
194 <listitem>
195 <para>
196 OVF localization, with multiple languages in a single OVF
197 file, is not yet supported.
198 </para>
199 </listitem>
200
201 <listitem>
202 <para>
203 Some OVF sections like StartupSection,
204 DeploymentOptionSection, and InstallSection are ignored.
205 </para>
206 </listitem>
207
208 <listitem>
209 <para>
210 OVF environment documents, including their property
211 sections and appliance configuration with ISO images, are
212 not yet supported.
213 </para>
214 </listitem>
215
216 <listitem>
217 <para>
218 Remote files using HTTP or other mechanisms are not yet
219 supported.
220 </para>
221 </listitem>
222
223 </itemizedlist>
224 </listitem>
225
226 <listitem>
227 <para>
228 Neither <emphasis role="bold">scale mode</emphasis> nor
229 <emphasis role="bold">seamless mode</emphasis> work correctly
230 with guests using OpenGL 3D features, such as with
231 Compiz-enabled window managers.
232 </para>
233 </listitem>
234
235 <listitem>
236 <para>
237 The RDP server in the &product-name; extension pack supports
238 only audio streams in format 22.05kHz stereo 16-bit. If the
239 RDP client requests any other audio format there will be no
240 audio.
241 </para>
242 </listitem>
243
244 <listitem>
245 <para>
246 Preserving the aspect ratio in scale mode works only on
247 Windows hosts and on Mac OS X hosts.
248 </para>
249 </listitem>
250
251 <listitem>
252 <para>
253 On <emphasis role="bold">Mac OS X hosts,</emphasis> the
254 following features are not yet implemented:
255 </para>
256
257 <itemizedlist>
258
259 <listitem>
260 <para>
261 Numlock emulation
262 </para>
263 </listitem>
264
265 <listitem>
266 <para>
267 CPU frequency metric
268 </para>
269 </listitem>
270
271 <listitem>
272 <para>
273 Memory ballooning
274 </para>
275 </listitem>
276
277 </itemizedlist>
278 </listitem>
279
280 <listitem>
281 <para>
282 <emphasis role="bold">Mac OS X guests:</emphasis>
283 </para>
284
285 <itemizedlist>
286
287 <listitem>
288 <para>
289 Mac OS X guests can only run on a certain host hardware.
290 For details about license and host hardware limitations.
291 See <xref linkend="intro-macosxguests" /> and check the
292 Apple software license conditions.
293 </para>
294 </listitem>
295
296 <listitem>
297 <para>
298 &product-name; does not provide Guest Additions for Mac OS
299 X at this time.
300 </para>
301 </listitem>
302
303 <listitem>
304 <para>
305 The graphics resolution currently defaults to 1024x768 as
306 Mac OS X falls back to the built-in EFI display support.
307 See <xref linkend="efividmode" /> for more information on
308 how to change EFI video modes.
309 </para>
310 </listitem>
311
312 <listitem>
313 <para>
314 Mac OS X guests only work with one CPU assigned to the VM.
315 Support for SMP will be provided in a future release.
316 </para>
317 </listitem>
318
319 <listitem>
320 <para>
321 Depending on your system and version of Mac OS X, you
322 might experience guest hangs after some time. This can be
323 fixed by turning off energy saving. Set the timeout to
324 "Never" in the system preferences.
325 </para>
326 </listitem>
327
328 <listitem>
329 <para>
330 By default, the &product-name; EFI enables debug output of
331 the Mac OS X kernel to help you diagnose boot problems.
332 Note that there is a lot of output and not all errors are
333 fatal. They would also show when using a physical Apple
334 Macintosh computer. You can turn off these messages by
335 using the following command:
336 </para>
337
338<screen>$ VBoxManage setextradata <replaceable>VM-name</replaceable> "VBoxInternal2/EfiBootArgs" " "</screen>
339
340 <para>
341 To revert to the previous behavior, use the following
342 command:
343 </para>
344
345<screen>$ VBoxManage setextradata <replaceable>VM-name</replaceable> "VBoxInternal2/EfiBootArgs" ""</screen>
346 </listitem>
347
348 <listitem>
349 <para>
350 It is currently not possible to start a Mac OS X guest in
351 safe mode by specifying the <option>-x</option> option in
352 <literal>VBoxInternal2/EfiBootArgs</literal> extradata.
353 </para>
354 </listitem>
355
356 </itemizedlist>
357 </listitem>
358
359 <listitem>
360 <para>
361 <emphasis role="bold">Oracle Solaris hosts:</emphasis>
362 </para>
363
364 <itemizedlist>
365
366 <listitem>
367 <para>
368 USB support on Oracle Solaris hosts requires Oracle
369 Solaris 11 version snv_124 or later. Webcams and other
370 isochronous devices are known to have poor performance.
371 </para>
372 </listitem>
373
374 <listitem>
375 <para>
376 Host Webcam passthrough is restricted to 640x480 frames at
377 20 frames per second due to limitations in the Oracle
378 Solaris V4L2 API. This may be addressed in a future Oracle
379 Solaris release.
380 </para>
381 </listitem>
382
383 <listitem>
384 <para>
385 No ACPI information, such as battery status or power
386 source, is reported to the guest.
387 </para>
388 </listitem>
389
390 <listitem>
391 <para>
392 No support for using wireless adapters with bridged
393 networking.
394 </para>
395 </listitem>
396
397 <listitem>
398 <para>
399 Crossbow-based bridged networking on Oracle Solaris 11
400 hosts does not work directly with aggregate links.
401 However, you can use <command>dladm</command> to manually
402 create a VNIC over the aggregate link and use that with a
403 VM. This limitation does not exist in Oracle Solaris 11u1
404 build 17 and later.
405 </para>
406 </listitem>
407
408 </itemizedlist>
409 </listitem>
410
411 <listitem>
412 <para>
413 Neither virtio nor Intel PRO/1000 drivers for
414 <emphasis role="bold">Windows XP guests</emphasis> support
415 segmentation offloading. Therefore Windows XP guests have
416 slower transmission rates comparing to other guest types.
417 Refer to MS Knowledge base article 842264 for additional
418 information.
419 </para>
420 </listitem>
421
422 <listitem>
423 <para>
424 <emphasis role="bold">Guest Additions for OS/2.</emphasis>
425 Seamless windows and automatic guest resizing will probably
426 never be implemented due to inherent limitations of the OS/2
427 graphics system.
428 </para>
429 </listitem>
430
431 <listitem>
432 <para>
433 Some guest operating systems predating ATAPI CD-ROMs may
434 exhibit long delays or entirely fail to boot in certain
435 configurations. This is most likely to happen when an
436 IDE/ATAPI CD-ROM exists alone on a primary or secondary IDE
437 channel.
438 </para>
439
440 <para>
441 Affected operating systems are MS OS/2 1.21: fails to boot
442 with an error message referencing COUNTRY.SYS and MS OS/2 1.3:
443 long boot delays. To avoid such problems, disable the emulated
444 IDE/ATAPI CD-ROM. The guest OS cannot use this device, anyway.
445 </para>
446 </listitem>
447
448 </itemizedlist>
449
450 </sect1>
451
452</chapter>
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