1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
|
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<!--
This file is autogenerated from formatdomaincaps.html.in
Do not edit this file. Changes will be lost.
-->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<link rel="stylesheet" type="text/css" href="main.css" />
<link rel="SHORTCUT ICON" href="32favicon.png" />
<title>libvirt: Domain capabilities XML format</title>
<meta name="description" content="libvirt, virtualization, virtualization API" />
</head>
<body>
<div id="body">
<div id="content">
<h1>Domain capabilities XML format</h1>
<ul><li>
<a href="#Overview">Overview</a>
</li><li>
<a href="#elements">Element and attribute overview</a>
<ul><li>
<a href="#elementsCPUAllocation">CPU Allocation</a>
</li><li>
<a href="#elementsOSBIOS">BIOS bootloader</a>
</li><li>
<a href="#elementsCPU">CPU configuration</a>
</li><li>
<a href="#elementsDevices">Devices</a>
<ul><li>
<a href="#elementsDisks">Hard drives, floppy disks, CDROMs</a>
</li><li>
<a href="#elementsGraphics">Graphical framebuffers</a>
</li><li>
<a href="#elementsVideo">Video device</a>
</li><li>
<a href="#elementsHostDev">Host device assignment</a>
</li></ul>
</li><li>
<a href="#elementsFeatures">Features</a>
<ul><li>
<a href="#elementsGIC">GIC capabilities</a>
</li></ul>
</li></ul>
</li></ul>
<h2>
<a name="Overview" shape="rect" id="Overview">Overview</a>
<a class="headerlink" href="#Overview" title="Permalink to this headline">¶</a>
</h2>
<p>Sometimes, when a new domain is to be created it may come handy to know
the capabilities of the hypervisor so the correct combination of devices and
drivers is used. For example, when management application is considering the
mode for a host device's passthrough there are several options depending not
only on host, but on hypervisor in question too. If the hypervisor is qemu
then it needs to be more recent to support VFIO, while legacy KVM is
achievable just fine with older qemus.</p>
<p>The main difference between
<a href="/html/libvirt-libvirt-host.html#virConnectGetCapabilities" shape="rect">
<code>virConnectGetCapabilities</code>
</a>
and the emulator capabilities API is, the former one aims more on
the host capabilities (e.g. NUMA topology, security models in
effect, etc.) while the latter one specializes on the hypervisor
capabilities.</p>
<p>While the <a href="formatcaps.html" shape="rect">Driver Capabilities</a> provides the
host capabilities (e.g NUMA topology, security models in effect, etc.), the
Domain Capabilities provides the hypervisor specific capabilities for
Management Applications to query and make decisions regarding what to
utilize.</p>
<p>The Domain Capabilities can provide information such as the correct
combination of devices and drivers that are supported. Knowing which host
and hypervisor specific options are available or supported would allow the
management application to choose an appropriate mode for a pass-through
host device as well as which adapter to utilize.</p>
<h2>
<a name="elements" shape="rect" id="elements">Element and attribute overview</a>
<a class="headerlink" href="#elements" title="Permalink to this headline">¶</a>
</h2>
<p> A new query interface was added to the virConnect API's to retrieve the
XML listing of the set of domain capabilities (<span class="since">Since
1.2.7</span>):</p>
<pre xml:space="preserve">
<a href="/html/libvirt-libvirt-domain.html#virConnectGetDomainCapabilities" shape="rect">virConnectGetDomainCapabilities</a>
</pre>
<p>The root element that emulator capability XML document starts with has
name <code>domainCapabilities</code>. It contains at least four direct
child elements:</p>
<pre xml:space="preserve">
<domainCapabilities>
<path>/usr/bin/qemu-system-x86_64</path>
<domain>kvm</domain>
<machine>pc-i440fx-2.1</machine>
<arch>x86_64</arch>
...
</domainCapabilities>
</pre>
<dl><dt><code>path</code></dt><dd>The full path to the emulator binary.</dd><dt><code>domain</code></dt><dd>Describes the <a href="formatdomain.html#elements" shape="rect">virtualization
type</a> (or so called domain type).</dd><dt><code>machine</code></dt><dd>The domain's <a href="formatdomain.html#elementsOSBIOS" shape="rect">machine
type</a>.</dd><dt><code>arch</code></dt><dd>The domain's <a href="formatdomain.html#elementsOSBIOS" shape="rect">
architecture</a>.</dd></dl>
<h3>
<a name="elementsCPUAllocation" shape="rect" id="elementsCPUAllocation">CPU Allocation</a>
<a class="headerlink" href="#elementsCPUAllocation" title="Permalink to this headline">¶</a>
</h3>
<p>Before any devices capability occurs, there might be a info on domain
wide capabilities, e.g. virtual CPUs:</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<vcpu max='255'/>
...
</domainCapabilities>
</pre>
<dl><dt><code>vcpu</code></dt><dd>The maximum number of supported virtual CPUs</dd></dl>
<h3>
<a name="elementsOSBIOS" shape="rect" id="elementsOSBIOS">BIOS bootloader</a>
<a class="headerlink" href="#elementsOSBIOS" title="Permalink to this headline">¶</a>
</h3>
<p>Sometimes users might want to tweak some BIOS knobs or use
UEFI. For cases like that, <a href="formatdomain.html#elementsOSBIOS" shape="rect"><code>os</code></a>
element exposes what values can be passed to its children.</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<os supported='yes'>
<loader supported='yes'>
<value>/usr/share/OVMF/OVMF_CODE.fd</value>
<enum name='type'>
<value>rom</value>
<value>pflash</value>
</enum>
<enum name='readonly'>
<value>yes</value>
<value>no</value>
</enum>
</loader>
</os>
...
<domainCapabilities>
</pre>
<p>For the <code>loader</code> element, the following can occur:</p>
<dl><dt><code>value</code></dt><dd>List of known loader paths. Currently this is only used
to advertise known locations of OVMF binaries for qemu. Binaries
will only be listed if they actually exist on disk.</dd><dt><code>type</code></dt><dd>Whether loader is a typical BIOS (<code>rom</code>) or
an UEFI binary (<code>pflash</code>). This refers to
<code>type</code> attribute of the <loader/>
element.</dd><dt><code>readonly</code></dt><dd>Options for the <code>readonly</code> attribute of the
<loader/> element.</dd></dl>
<h3>
<a name="elementsCPU" shape="rect" id="elementsCPU">CPU configuration</a>
<a class="headerlink" href="#elementsCPU" title="Permalink to this headline">¶</a>
</h3>
<p>
The <code>cpu</code> element exposes options usable for configuring
<a href="formatdomain.html#elementsCPU" shape="rect">guest CPUs</a>.
</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<cpu>
<mode name='host-passthrough' supported='yes'/>
<mode name='host-model' supported='yes'>
<model fallback='allow'>Broadwell</model>
<vendor>Intel</vendor>
<feature policy='disable' name='aes'/>
<feature policy='require' name='vmx'/>
</mode>
<mode name='custom' supported='yes'>
<model usable='no'>Broadwell</model>
<model usable='yes'>Broadwell-noTSX</model>
<model usable='no'>Haswell</model>
...
</mode>
</cpu>
...
<domainCapabilities>
</pre>
<p>
Each CPU mode understood by libvirt is described with a
<code>mode</code> element which tells whether the particular mode
is supported and provides (when applicable) more details about it:
</p>
<dl><dt><code>host-passthrough</code></dt><dd>No mode specific details are provided.</dd><dt><code>host-model</code></dt><dd>
If <code>host-model</code> is supported by the hypervisor, the
<code>mode</code> describes the guest CPU which will be used when
starting a domain with <code>host-model</code> CPU. The hypervisor
specifics (such as unsupported CPU models or features, machine type,
etc.) may be accounted for in this guest CPU specification and thus
the CPU can be different from the one shown in host capabilities XML.
This is indicated by the <code>fallback</code> attribute of the
<code>model</code> sub element: <code>allow</code> means not all
specifics were accounted for and thus the CPU a guest will see may
be different; <code>forbid</code> indicates that the CPU a guest will
see should match this CPU definition.
</dd><dt><code>custom</code></dt><dd>
The <code>mode</code> element contains a list of supported CPU
models, each described by a dedicated <code>model</code> element.
The <code>usable</code> attribute specifies whether the model can
be used on the host. A special value <code>unknown</code> indicates
libvirt does not have enough information to provide the usability
data.
</dd></dl>
<h3>
<a name="elementsDevices" shape="rect" id="elementsDevices">Devices</a>
<a class="headerlink" href="#elementsDevices" title="Permalink to this headline">¶</a>
</h3>
<p>
Another set of XML elements describe the supported devices and their
capabilities. All devices occur as children of the main
<code>devices</code> element.
</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<devices>
<disk supported='yes'>
<enum name='diskDevice'>
<value>disk</value>
<value>cdrom</value>
<value>floppy</value>
<value>lun</value>
</enum>
...
</disk>
<hostdev supported='no'/>
</devices>
</domainCapabilities>
</pre>
<p>Reported capabilities are expressed as an enumerated list of available
options for each of the element or attribute. For example, the
<disk/> element has an attribute <code>device</code> which can
support the values <code>disk</code>, <code>cdrom</code>,
<code>floppy</code>, or <code>lun</code>.</p>
<h4>
<a name="elementsDisks" shape="rect" id="elementsDisks">Hard drives, floppy disks, CDROMs</a>
<a class="headerlink" href="#elementsDisks" title="Permalink to this headline">¶</a>
</h4>
<p>Disk capabilities are exposed under the <code>disk</code> element. For
instance:</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<devices>
<disk supported='yes'>
<enum name='diskDevice'>
<value>disk</value>
<value>cdrom</value>
<value>floppy</value>
<value>lun</value>
</enum>
<enum name='bus'>
<value>ide</value>
<value>fdc</value>
<value>scsi</value>
<value>virtio</value>
<value>xen</value>
<value>usb</value>
<value>uml</value>
<value>sata</value>
<value>sd</value>
</enum>
</disk>
...
</devices>
</domainCapabilities>
</pre>
<dl><dt><code>diskDevice</code></dt><dd>Options for the <code>device</code> attribute of the <disk/>
element.</dd><dt><code>bus</code></dt><dd>Options for the <code>bus</code> attribute of the <target/>
element for a <disk/>.</dd></dl>
<h4>
<a name="elementsGraphics" shape="rect" id="elementsGraphics">Graphical framebuffers</a>
<a class="headerlink" href="#elementsGraphics" title="Permalink to this headline">¶</a>
</h4>
<p>Graphics device capabilities are exposed under the
<code>graphics</code> element. For instance:</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<devices>
<graphics supported='yes'>
<enum name='type'>
<value>sdl</value>
<value>vnc</value>
<value>spice</value>
</enum>
</graphics>
...
</devices>
</domainCapabilities>
</pre>
<dl><dt><code>type</code></dt><dd>Options for the <code>type</code> attribute of the <graphics/>
element.</dd></dl>
<h4>
<a name="elementsVideo" shape="rect" id="elementsVideo">Video device</a>
<a class="headerlink" href="#elementsVideo" title="Permalink to this headline">¶</a>
</h4>
<p>Video device capabilities are exposed under the
<code>video</code> element. For instance:</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<devices>
<video supported='yes'>
<enum name='modelType'>
<value>vga</value>
<value>cirrus</value>
<value>vmvga</value>
<value>qxl</value>
<value>virtio</value>
</enum>
</video>
...
</devices>
</domainCapabilities>
</pre>
<dl><dt><code>modelType</code></dt><dd>Options for the <code>type</code> attribute of the
<video><model> element.</dd></dl>
<h4>
<a name="elementsHostDev" shape="rect" id="elementsHostDev">Host device assignment</a>
<a class="headerlink" href="#elementsHostDev" title="Permalink to this headline">¶</a>
</h4>
<p>Some host devices can be passed through to a guest (e.g. USB, PCI and
SCSI). Well, only if the following is enabled:</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<devices>
<hostdev supported='yes'>
<enum name='mode'>
<value>subsystem</value>
<value>capabilities</value>
</enum>
<enum name='startupPolicy'>
<value>default</value>
<value>mandatory</value>
<value>requisite</value>
<value>optional</value>
</enum>
<enum name='subsysType'>
<value>usb</value>
<value>pci</value>
<value>scsi</value>
</enum>
<enum name='capsType'>
<value>storage</value>
<value>misc</value>
<value>net</value>
</enum>
<enum name='pciBackend'>
<value>default</value>
<value>kvm</value>
<value>vfio</value>
<value>xen</value>
</enum>
</hostdev>
</devices>
</domainCapabilities>
</pre>
<dl><dt><code>mode</code></dt><dd>Options for the <code>mode</code> attribute of the <hostdev/>
element.</dd><dt><code>startupPolicy</code></dt><dd>Options for the <code>startupPolicy</code> attribute of the
<hostdev/> element.</dd><dt><code>subsysType</code></dt><dd>Options for the <code>type</code> attribute of the <hostdev/>
element in case of <code>mode="subsystem"</code>.</dd><dt><code>capsType</code></dt><dd>Options for the <code>type</code> attribute of the <hostdev/>
element in case of <code>mode="capabilities"</code>.</dd><dt><code>pciBackend</code></dt><dd>Options for the <code>name</code> attribute of the <driver/>
element.</dd></dl>
<h3>
<a name="elementsFeatures" shape="rect" id="elementsFeatures">Features</a>
<a class="headerlink" href="#elementsFeatures" title="Permalink to this headline">¶</a>
</h3>
<p>One more set of XML elements describe the supported features and
their capabilities. All features occur as children of the main
<code>features</code> element.</p>
<pre xml:space="preserve">
<domainCapabilities>
...
<features>
<gic supported='yes'>
<enum name='version'>
<value>2</value>
<value>3</value>
</enum>
</gic>
</features>
</domainCapabilities>
</pre>
<p>Reported capabilities are expressed as an enumerated list of
possible values for each of the elements or attributes. For example, the
<code>gic</code> element has an attribute <code>version</code> which can
support the values <code>2</code> or <code>3</code>.</p>
<p>For information about the purpose of each feature, see the
<a href="formatdomain.html#elementsFeatures" shape="rect">relevant section</a> in
the domain XML documentation.
</p>
<h4>
<a name="elementsGIC" shape="rect" id="elementsGIC">GIC capabilities</a>
<a class="headerlink" href="#elementsGIC" title="Permalink to this headline">¶</a>
</h4>
<p>GIC capabilities are exposed under the <code>gic</code> element.</p>
<dl><dt><code>version</code></dt><dd>Options for the <code>version</code> attribute of the
<code>gic</code> element.</dd></dl>
</div>
</div>
<div id="nav">
<div id="home">
<a href="index.html">Home</a>
</div>
<div id="jumplinks">
<ul><li>
<a href="downloads.html">Download</a>
</li><li>
<a href="contribute.html">Contribute</a>
</li><li>
<a href="docs.html">Learn</a>
</li></ul>
</div>
<div id="search">
<form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><div>
<input name="query" type="text" size="12" value="" />
<input name="submit" type="submit" value="Go" />
</div></form>
</div>
</div>
<div id="footer">
<div id="contact">
<h3>Contact</h3>
<ul><li>
<a href="contact.html#email">email</a>
</li><li>
<a href="contact.html#irc">irc</a>
</li></ul>
</div>
<div id="community">
<h3>Community</h3>
<ul><li>
<a href="https://twitter.com/hashtag/libvirt">twitter</a>
</li><li>
<a href="https://plus.google.com/communities/109522598353007505282">google+</a>
</li><li>
<a href="http://stackoverflow.com/questions/tagged/libvirt">stackoverflow</a>
</li><li>
<a href="http://serverfault.com/questions/tagged/libvirt">serverfault</a>
</li></ul>
</div>
<div id="conduct">
Participants in the libvirt project agree to abide by <a href="governance.html#codeofconduct">the project code of conduct</a></div>
<br class="clear" />
</div>
</body>
</html>
|
