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 Hardware 2D video playback acceleration support for Windows
35 guests
36 </para>
37 </listitem>
38
39<!-- <listitem>
40 <para>
41 PCI passthrough (Linux hosts only)
42 </para>
43 </listitem>-->
44
45 <listitem>
46 <para>
47 Mac OS X guests (Mac OS X hosts only)
48 </para>
49 </listitem>
50
51 <listitem>
52 <para>
53 ICH9 chipset emulation
54 </para>
55 </listitem>
56
57 <listitem>
58 <para>
59 EFI firmware
60 </para>
61 </listitem>
62
63 <listitem>
64 <para>
65 Host CD/DVD drive passthrough
66 </para>
67 </listitem>
68
69 <listitem>
70 <para>
71 Support of iSCSI using internal networking
72 </para>
73 </listitem>
74
75 <listitem>
76 <para>
77 Using &product-name; and Hyper-V on the same host
78 </para>
79 </listitem>
80
81 </itemizedlist>
82
83 </sect1>
84
85 <sect1 id="KnownProblems">
86
87 <title>Known Issues</title>
88
89 <para>
90 The following section describes known problems with this release
91 of &product-name;. Unless marked otherwise, these issues are
92 planned to be fixed in later releases.
93 </para>
94
95 <itemizedlist>
96
97 <listitem>
98 <para>
99 Poor performance when using &product-name; and
100 <emphasis role="bold">Hyper-V</emphasis> on the same host. To
101 fix this, certain Windows features like "Hyper-V Platform",
102 "Virtual Machine Platform" and "Windows Hypervisor Platform"
103 must be turned off, followed by a host reboot.
104 </para>
105
106 <para>
107 Additionally, the Microsoft Device Guard and Credential Guard
108 hardware readiness tool might have to be used in order to turn
109 off more features. For example, by running the following
110 command:
111 </para>
112
113<screen>.\DG_Readiness_Tool_vX.X.ps1 -Disable -AutoReboot</screen>
114
115 <note>
116 <para>
117 Disabling Device Guard and Credential Guard features will
118 have an impact on the overall security of the host. Please
119 contact your Administrator beforehand regarding this.
120 </para>
121 </note>
122 </listitem>
123
124 <listitem>
125 <para>
126 The following <emphasis role="bold">Guest SMP (multiprocessor)
127 limitations</emphasis> exist:
128 </para>
129
130 <itemizedlist>
131
132 <listitem>
133 <para>
134 <emphasis role="bold">Poor performance</emphasis> with
135 32-bit guests on AMD CPUs. This affects mainly Windows and
136 Oracle Solaris guests, but possibly also some Linux kernel
137 revisions. Partially solved for 32-bit Windows NT, 2000,
138 XP, and 2003 guests. Requires the Guest Additions to be
139 installed.
140 </para>
141 </listitem>
142
143 <listitem>
144 <para>
145 <emphasis role="bold">Poor performance</emphasis> with
146 32-bit guests on certain Intel CPU models that do not
147 include virtual APIC hardware optimization support. This
148 affects mainly Windows and Oracle Solaris guests, but
149 possibly also some Linux kernel revisions. Partially
150 solved for 32-bit Windows NT, 2000, XP, and 2003 guests.
151 Requires the Guest Additions to be installed.
152 </para>
153 </listitem>
154
155 </itemizedlist>
156 </listitem>
157
158 <listitem>
159 <para>
160 <emphasis role="bold">NX (no execute, data execution
161 prevention)</emphasis> only works for guests running on 64-bit
162 hosts and requires that hardware virtualization be enabled.
163 </para>
164 </listitem>
165
166 <listitem>
167 <para>
168 <emphasis role="bold">Guest control.</emphasis> On Windows
169 guests, a process started using the guest control execute
170 support will not be able to display a graphical user interface
171 <emphasis>unless</emphasis> the user account under which it is
172 running is currently logged in and has a desktop session.
173 </para>
174
175 <para>
176 Also, to use accounts without or with an empty password, the
177 guest's group policy must be changed. To do so, open the group
178 policy editor on the command line by typing
179 <command>gpedit.msc</command>, open the key <literal>Computer
180 Configuration\Windows Settings\Security Settings\Local
181 Policies\Security Options</literal> and change the value of
182 <literal>Accounts: Limit local account use of blank passwords
183 to console logon only</literal> to Disabled.
184 </para>
185 </listitem>
186
187 <listitem>
188 <para>
189 <emphasis role="bold">Compacting virtual disk images is
190 limited to VDI files.</emphasis> The <command>VBoxManage
191 modifymedium --compact</command> command is currently only
192 implemented for VDI files. At the moment the only way to
193 optimize the size of a virtual disk images in other formats,
194 such as VMDK or VHD, is to clone the image and then use the
195 cloned image in the VM configuration.
196 </para>
197 </listitem>
198
199 <listitem>
200 <para>
201 <emphasis role="bold">OVF import/export:</emphasis>
202 </para>
203
204 <itemizedlist>
205
206 <listitem>
207 <para>
208 OVF localization, with multiple languages in a single OVF
209 file, is not yet supported.
210 </para>
211 </listitem>
212
213 <listitem>
214 <para>
215 Some OVF sections like StartupSection,
216 DeploymentOptionSection, and InstallSection are ignored.
217 </para>
218 </listitem>
219
220 <listitem>
221 <para>
222 OVF environment documents, including their property
223 sections and appliance configuration with ISO images, are
224 not yet supported.
225 </para>
226 </listitem>
227
228 <listitem>
229 <para>
230 Remote files using HTTP or other mechanisms are not yet
231 supported.
232 </para>
233 </listitem>
234
235 </itemizedlist>
236 </listitem>
237
238 <listitem>
239 <para>
240 Neither <emphasis role="bold">scale mode</emphasis> nor
241 <emphasis role="bold">seamless mode</emphasis> work correctly
242 with guests using OpenGL 3D features, such as with
243 Compiz-enabled window managers.
244 </para>
245 </listitem>
246
247 <listitem>
248 <para>
249 The RDP server in the &product-name; extension pack supports
250 only audio streams in format 22.05kHz stereo 16-bit. If the
251 RDP client requests any other audio format there will be no
252 audio.
253 </para>
254 </listitem>
255
256 <listitem>
257 <para>
258 Preserving the aspect ratio in scale mode works only on
259 Windows hosts and on Mac OS X hosts.
260 </para>
261 </listitem>
262
263 <listitem>
264 <para>
265 On <emphasis role="bold">Mac OS X hosts,</emphasis> the
266 following features are not yet implemented:
267 </para>
268
269 <itemizedlist>
270
271 <listitem>
272 <para>
273 Numlock emulation
274 </para>
275 </listitem>
276
277 <listitem>
278 <para>
279 CPU frequency metric
280 </para>
281 </listitem>
282
283 <listitem>
284 <para>
285 Memory ballooning
286 </para>
287 </listitem>
288
289 </itemizedlist>
290 </listitem>
291
292 <listitem>
293 <para>
294 <emphasis role="bold">Mac OS X guests:</emphasis>
295 </para>
296
297 <itemizedlist>
298
299 <listitem>
300 <para>
301 Mac OS X guests can only run on a certain host hardware.
302 For details about license and host hardware limitations.
303 See <xref linkend="intro-macosxguests" /> and check the
304 Apple software license conditions.
305 </para>
306 </listitem>
307
308 <listitem>
309 <para>
310 &product-name; does not provide Guest Additions for Mac OS
311 X at this time.
312 </para>
313 </listitem>
314
315 <listitem>
316 <para>
317 The graphics resolution currently defaults to 1024x768 as
318 Mac OS X falls back to the built-in EFI display support.
319 See <xref linkend="efividmode" /> for more information on
320 how to change EFI video modes.
321 </para>
322 </listitem>
323
324 <listitem>
325 <para>
326 Mac OS X guests only work with one CPU assigned to the VM.
327 Support for SMP will be provided in a future release.
328 </para>
329 </listitem>
330
331 <listitem>
332 <para>
333 Depending on your system and version of Mac OS X, you
334 might experience guest hangs after some time. This can be
335 fixed by turning off energy saving. Set the timeout to
336 "Never" in the system preferences.
337 </para>
338 </listitem>
339
340 <listitem>
341 <para>
342 By default, the &product-name; EFI enables debug output of
343 the Mac OS X kernel to help you diagnose boot problems.
344 Note that there is a lot of output and not all errors are
345 fatal. They would also show when using a physical Apple
346 Macintosh computer. You can turn off these messages by
347 using the following command:
348 </para>
349
350<screen>$ VBoxManage setextradata <replaceable>VM-name</replaceable> "VBoxInternal2/EfiBootArgs" " "</screen>
351
352 <para>
353 To revert to the previous behavior, use the following
354 command:
355 </para>
356
357<screen>$ VBoxManage setextradata <replaceable>VM-name</replaceable> "VBoxInternal2/EfiBootArgs" ""</screen>
358 </listitem>
359
360 <listitem>
361 <para>
362 It is currently not possible to start a Mac OS X guest in
363 safe mode by specifying the <option>-x</option> option in
364 <literal>VBoxInternal2/EfiBootArgs</literal> extradata.
365 </para>
366 </listitem>
367
368 </itemizedlist>
369 </listitem>
370
371 <listitem>
372 <para>
373 <emphasis role="bold">Oracle Solaris hosts:</emphasis>
374 </para>
375
376 <itemizedlist>
377
378 <listitem>
379 <para>
380 USB support on Oracle Solaris hosts requires Oracle
381 Solaris 11 version snv_124 or later. Webcams and other
382 isochronous devices are known to have poor performance.
383 </para>
384 </listitem>
385
386 <listitem>
387 <para>
388 Host Webcam passthrough is restricted to 640x480 frames at
389 20 frames per second due to limitations in the Oracle
390 Solaris V4L2 API. This may be addressed in a future Oracle
391 Solaris release.
392 </para>
393 </listitem>
394
395 <listitem>
396 <para>
397 No ACPI information, such as battery status or power
398 source, is reported to the guest.
399 </para>
400 </listitem>
401
402 <listitem>
403 <para>
404 No support for using wireless adapters with bridged
405 networking.
406 </para>
407 </listitem>
408
409 <listitem>
410 <para>
411 Crossbow-based bridged networking on Oracle Solaris 11
412 hosts does not work directly with aggregate links.
413 However, you can use <command>dladm</command> to manually
414 create a VNIC over the aggregate link and use that with a
415 VM. This limitation does not exist in Oracle Solaris 11u1
416 build 17 and later.
417 </para>
418 </listitem>
419
420 </itemizedlist>
421 </listitem>
422
423 <listitem>
424 <para>
425 Neither virtio nor Intel PRO/1000 drivers for
426 <emphasis role="bold">Windows XP guests</emphasis> support
427 segmentation offloading. Therefore Windows XP guests have
428 slower transmission rates comparing to other guest types.
429 Refer to MS Knowledge base article 842264 for additional
430 information.
431 </para>
432 </listitem>
433
434 <listitem>
435 <para>
436 <emphasis role="bold">Guest Additions for OS/2.</emphasis>
437 Seamless windows and automatic guest resizing will probably
438 never be implemented due to inherent limitations of the OS/2
439 graphics system.
440 </para>
441 </listitem>
442
443 <listitem>
444 <para>
445 Some guest operating systems predating ATAPI CD-ROMs may
446 exhibit long delays or entirely fail to boot in certain
447 configurations. This is most likely to happen when an
448 IDE/ATAPI CD-ROM exists alone on a primary or secondary IDE
449 channel.
450 </para>
451
452 <para>
453 Affected operating systems are MS OS/2 1.21: fails to boot
454 with an error message referencing COUNTRY.SYS and MS OS/2 1.3:
455 long boot delays. To avoid such problems, disable the emulated
456 IDE/ATAPI CD-ROM. The guest OS cannot use this device, anyway.
457 </para>
458 </listitem>
459
460 </itemizedlist>
461
462 </sect1>
463
464</chapter>
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