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 VirtualBox 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 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 pass-through (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 pass-through
66 </para>
67 </listitem>
68
69 <listitem>
70 <para>
71 Support of iSCSI via internal networking
72 </para>
73 </listitem>
74
75 </itemizedlist>
76
77 </sect1>
78
79 <sect1 id="KnownProblems">
80
81 <title>Known Issues</title>
82
83 <para>
84 The following section describes known problems with this release
85 of VirtualBox. Unless marked otherwise, these issues are planned
86 to be fixed in later releases.
87 </para>
88
89 <itemizedlist>
90
91 <listitem>
92 <para>
93 The following <emphasis role="bold">Guest SMP (multiprocessor)
94 limitations</emphasis> exist:
95 </para>
96
97 <itemizedlist>
98
99 <listitem>
100 <para>
101 <emphasis role="bold">Poor performance</emphasis> with
102 32-bit guests on AMD CPUs. This affects mainly Windows and
103 Solaris guests, but possibly also some Linux kernel
104 revisions. Partially solved in 3.0.6 for 32 bits Windows
105 NT, 2000, XP and 2003 guests. Requires 3.0.6 or higher
106 Guest Additions to be installed.
107 </para>
108 </listitem>
109
110 <listitem>
111 <para>
112 <emphasis role="bold">Poor performance</emphasis> with
113 32-bit guests on certain Intel CPU models that do not
114 include virtual APIC hardware optimization support. This
115 affects mainly Windows and Solaris guests, but possibly
116 also some Linux kernel revisions. Partially solved in
117 3.0.12 for 32 bits Windows NT, 2000, XP, and 2003 guests.
118 Requires 3.0.12 or higher Guest Additions to be installed.
119 </para>
120 </listitem>
121
122 </itemizedlist>
123 </listitem>
124
125 <listitem>
126 <para>
127 <emphasis role="bold">NX (no execute, data execution
128 prevention)</emphasis> only works for guests running on 64-bit
129 hosts or guests running on 32-bit hosts with PAE enabled and
130 requires that hardware virtualization be enabled.
131 </para>
132 </listitem>
133
134 <listitem>
135 <para>
136 For <emphasis role="bold">basic Direct3D support in Windows
137 guests</emphasis> to work, the Guest Additions must be
138 installed in Windows "safe mode". Press F8 when the Windows
139 guest is booting and select "Safe mode", then install the
140 Guest Additions. Otherwise the Windows file protection
141 mechanism will interfere with the replacement DLLs installed
142 by VirtualBox and keep restoring the original Windows system
143 DLLs.
144
145 <note>
146 <para>
147 This does <emphasis>not</emphasis> apply to the WDDM
148 Direct3D video driver available for Vista and Windows 7
149 guests shipped with VirtualBox 4.1.
150 </para>
151 </note>
152 </para>
153 </listitem>
154
155 <listitem>
156 <para>
157 <emphasis role="bold">Guest control.</emphasis> On Windows
158 guests, a process lauched via the guest control execute
159 support will not be able to display a graphical user interface
160 <emphasis>unless</emphasis> the user account under which it is
161 running is currently logged in and has a desktop session.
162 </para>
163
164 <para>
165 Also, to use accounts without or with an empty password, the
166 guest's group policy must be changed. To do so, open the group
167 policy editor on the command line by typing
168 <computeroutput>gpedit.msc</computeroutput>, open the key
169 <emphasis>Computer Configuration\Windows Settings\Security
170 Settings\Local Policies\Security Options</emphasis> and change
171 the value of <emphasis>Accounts: Limit local account use of
172 blank passwords to console logon only</emphasis> to
173 <emphasis>Disabled</emphasis>.
174 </para>
175 </listitem>
176
177 <listitem>
178 <para>
179 <emphasis role="bold">Compacting virtual disk images is
180 limited to VDI files.</emphasis> The <code>VBoxManage modifyhd
181 --compact</code> command is currently only implemented for VDI
182 files. At the moment the only way to optimize the size of a
183 virtual disk images in other formats (VMDK, VHD) is to clone
184 the image and then use the cloned image in the VM
185 configuration.
186 </para>
187 </listitem>
188
189 <listitem>
190 <para>
191 <emphasis role="bold">OVF import/export:</emphasis>
192 </para>
193
194 <itemizedlist>
195
196 <listitem>
197 <para>
198 OVF localization, with multiple languages in a single OVF
199 file, is not yet supported.
200 </para>
201 </listitem>
202
203 <listitem>
204 <para>
205 Some OVF sections like StartupSection,
206 DeploymentOptionSection, and InstallSection are ignored.
207 </para>
208 </listitem>
209
210 <listitem>
211 <para>
212 OVF environment documents, including their property
213 sections and appliance configuration with ISO images, are
214 not yet supported.
215 </para>
216 </listitem>
217
218 <listitem>
219 <para>
220 Remote files via HTTP or other mechanisms are not yet
221 supported.
222 </para>
223 </listitem>
224
225 </itemizedlist>
226 </listitem>
227
228 <listitem>
229 <para>
230 Neither <emphasis role="bold">scale mode</emphasis> nor
231 <emphasis
232 role="bold">seamless mode</emphasis> work
233 correctly with guests using OpenGL 3D features, such as with
234 compiz-enabled window managers.
235 </para>
236 </listitem>
237
238 <listitem>
239 <para>
240 The RDP server in the VirtualBox extension pack supports only
241 audio streams in format 22.05kHz stereo 16 bit. If the RDP
242 client requests any other audio format there will be no audio.
243 </para>
244 </listitem>
245
246 <listitem>
247 <para>
248 Preserving the aspect ratio in scale mode works only on
249 Windows hosts and on Mac OS X hosts.
250 </para>
251 </listitem>
252
253 <listitem>
254 <para>
255 On <emphasis role="bold">Mac OS X hosts,</emphasis> the
256 following features are not yet implemented:
257 </para>
258
259 <itemizedlist>
260
261 <listitem>
262 <para>
263 Numlock emulation
264 </para>
265 </listitem>
266
267 <listitem>
268 <para>
269 CPU frequency metric
270 </para>
271 </listitem>
272
273 <listitem>
274 <para>
275 Memory ballooning
276 </para>
277 </listitem>
278
279 </itemizedlist>
280 </listitem>
281
282 <listitem>
283 <para>
284 <emphasis role="bold">Mac OS X guests:</emphasis>
285 </para>
286
287 <itemizedlist>
288
289 <listitem>
290 <para>
291 Mac OS X guests can only run on a certain host hardware.
292 For details about license and host hardware limitations.
293 See <xref linkend="intro-macosxguests" /> and check the
294 Apple software license conditions.
295 </para>
296 </listitem>
297
298 <listitem>
299 <para>
300 VirtualBox does not provide Guest Additions for Mac OS X
301 at this time.
302 </para>
303 </listitem>
304
305 <listitem>
306 <para>
307 The graphics resolution currently defaults to 1024x768 as
308 Mac OS X falls back to the built-in EFI display support.
309 See <xref linkend="efividmode" /> for more information on
310 how to change EFI video modes.
311 </para>
312 </listitem>
313
314 <listitem>
315 <para>
316 Mac OS X guests only work with one CPU assigned to the VM.
317 Support for SMP will be provided in a future release.
318 </para>
319 </listitem>
320
321 <listitem>
322 <para>
323 Depending on your system and version of Mac OS X, you
324 might experience guest hangs after some time. This can be
325 fixed by turning off energy saving. Set timeout to "Never"
326 in the system preferences.
327 </para>
328 </listitem>
329
330 <listitem>
331 <para>
332 By default, the VirtualBox EFI enables debug output of the
333 Mac OS X kernel to help you diagnose boot problems. Note
334 that there is a lot of output and not all errors are
335 fatal. They would also show when using a physical Apple
336 Macintosh computer. You can turn off these messages by
337 issuing this command:
338
339<screen>VBoxManage setextradata "VM name" "VBoxInternal2/EfiBootArgs" " "</screen>
340
341 To revert to the previous behavior, use:
342
343<screen>VBoxManage setextradata "VM name" "VBoxInternal2/EfiBootArgs" ""</screen>
344 </para>
345 </listitem>
346
347 <listitem>
348 <para>
349 It is currently not possible to start a Mac OS X guest in
350 safe mode by specifying "-x" option in
351 "VBoxInternal2/EfiBootArgs" extradata.
352 </para>
353 </listitem>
354
355 </itemizedlist>
356 </listitem>
357
358 <listitem>
359 <para>
360 <emphasis role="bold">Solaris hosts:</emphasis>
361 </para>
362
363 <itemizedlist>
364
365 <listitem>
366 <para>
367 There is no support for USB devices connected to Solaris
368 10 hosts.
369 </para>
370 </listitem>
371
372 <listitem>
373 <para>
374 USB support on Solaris hosts requires Solaris 11 version
375 snv_124 or higher. Webcams and other isochronous devices
376 are known to have poor performance.
377 </para>
378 </listitem>
379
380 <listitem>
381 <para>
382 Host Webcam passthrough is restricted to 640x480 frames at
383 20 frames per second due to limitations in the Solaris
384 V4L2 API. This may be addressed in a future Solaris
385 release.
386 </para>
387 </listitem>
388
389 <listitem>
390 <para>
391 No ACPI information, such as battery status or power
392 source, is reported to the guest.
393 </para>
394 </listitem>
395
396 <listitem>
397 <para>
398 No support for using wireless adapters with bridged
399 networking.
400 </para>
401 </listitem>
402
403 <listitem>
404 <para>
405 Crossbow-based bridged networking on Solaris 11 hosts does
406 not work directly with aggregate links. However, you can
407 use <computeroutput>dladm</computeroutput> to manually
408 create a VNIC over the aggregate link and use that with a
409 VM. This limitation does not exist in Solaris 11u1 build
410 17 and newer.
411 </para>
412 </listitem>
413
414 </itemizedlist>
415 </listitem>
416
417 <listitem>
418 <para>
419 <emphasis role="bold">Guest Additions of version 4.1, 4.1.2
420 and 4.1.4 for Windows.</emphasis> The VirtualBox WDDM Video
421 driver may be installed and remain in the guest system when
422 Guest additions uninstallation is performed. This is caused by
423 a bug in Guest Additions uninstaller.
424 </para>
425
426 <note>
427 <para>
428 This does <emphasis>not</emphasis> apply to a Guest
429 Additions update. Installing one version of Guest Additions
430 on top of another works correctly.
431 </para>
432 </note>
433
434 <para>
435 To solve this problem, uninstall the VirtualBox WDDM Video
436 driver manually. Open Device Manager, and check whether the
437 Display Adapter is named "VirtualBox Graphics Adapter ..". If
438 not, there is nothing to be done. If it is, right-click the
439 VirtualBox Graphics Adapter in Device Manager, select
440 <emphasis role="bold">Uninstall</emphasis>, check
441 <emphasis role="bold">Delete the Driver Software for this
442 Device</emphasis> and click
443 <emphasis role="bold">OK</emphasis>. Once uninstallation is
444 done, start Device Manager, go to the Action menu and select
445 <emphasis role="bold">Scan for Hardware Change</emphasis>s to
446 ensure that the correct Windows default driver be picked up
447 for the Graphics adapter.
448 </para>
449 </listitem>
450
451 <listitem>
452 <para>
453 Neither <emphasis>virtio</emphasis> nor <emphasis>Intel
454 PRO/1000 </emphasis> drivers for <emphasis role="bold">Windows
455 XP guests</emphasis> support segmentation offloading.
456 Therefore Windows XP guests have slower transmission rates
457 comparing to other guest types. Refer to MS Knowledge base
458 article 842264 for additional information.
459 </para>
460 </listitem>
461
462 <listitem>
463 <para>
464 <emphasis role="bold">Guest Additions for OS/2.</emphasis>
465 Shared folders are not yet supported with OS/2 guests. In
466 addition, seamless windows and automatic guest resizing will
467 probably never be implemented due to inherent limitations of
468 the OS/2 graphics system.
469 </para>
470 </listitem>
471
472 <listitem>
473 <para>
474 Some guest operating systems predating ATAPI CD-ROMs may
475 exhibit long delays or entirely fail to boot in certain
476 configurations. This is most likely to happen when an
477 IDE/ATAPI CD-ROM exists alone on a primary or secondary IDE
478 channel.
479 </para>
480
481 <para>
482 Affected operating systems are MS OS/2 1.21: fails to boot
483 with an error message referencing COUNTRY.SYS and MS OS/2 1.3:
484 long boot delays. To avoid such problems, disable the emulated
485 IDE/ATAPI CD-ROM. The guest OS cannot use this device, anyway.
486 </para>
487 </listitem>
488
489 </itemizedlist>
490
491 </sect1>
492
493</chapter>
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