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Add support for <hostdev mode="capabilities">

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The <hostdev> device type has long had a redundant "mode"
attribute, which has always been "subsys". This finally
introduces a new mode "capabilities", which will be used
by the LXC driver for device assignment. Since container
based virtualization uses a single kernel, the idea of
assigning physical PCI devices doesn't make sense. It is
still reasonable to assign USB devices, but for assigning
arbitrary nodes in /dev, the new 'capabilities' mode is
to be used.

The first capability support is 'storage', which is for
assignment of block devices. Functionally this is really
pretty similar to the <disk> support. The only difference
is the device node name is identical in both host and
container namespaces.

    <hostdev mode='capabilities' type='storage'>
      <source>
        <block>/dev/sdf1</block>
      </source>
    </hostdev>

The second capability support is 'misc', which is for
assignment of character devices. There is no existing
parallel to this. Again the device node is the same
inside & outside the container.

    <hostdev mode='capabilities' type='misc'>
      <source>
        <char>/dev/input/event3</char>
      </source>
    </hostdev>

The reason for keeping the char & storage devices
separate in the domain XML, is to mirror the split
in the node device XML. NB the node device XML does
not yet report character devices, but that's another
new patch to come

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange
2012-11-23 13:50:29 +00:00
parent 347a712ab1
commit aae0fc2a92
8 changed files with 455 additions and 82 deletions
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55
docs/formatdomain.html.in
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@@ -2123,13 +2123,15 @@
</dd>
</dl>
<h4><a name="elementsUSB">USB and PCI devices</a></h4>
<h4><a name="elementsHostDev">Host device assignment</a></h4>
<h5><a href="elementsHostDevSubsys">USB / PCI devices</a></h5>
<p>
USB and PCI devices attached to the host can be passed through
to the guest using
the <code>hostdev</code> element. <span class="since">since after
0.4.4 for USB and 0.6.0 for PCI (KVM only)</span>:
to the guest using the <code>hostdev</code> element.
<span class="since">since after 0.4.4 for USB and 0.6.0 for PCI
(KVM only)</span>:
</p>
<pre>
@@ -2247,6 +2249,51 @@
more details on the address element.
</dl>
<h5><a href="elementsHostDevCaps">Block / character devices</a></h5>
<p>
Block / character devices from the host can be passed through
to the guest using the <code>hostdev</code> element. This is
only possible with container based virtualization.
<span class="since">since after 1.0.1 for LXC</span>:
</p>
<pre>
...
&lt;hostdev mode='capabilities' type='storage'&gt;
&lt;source&gt;
&lt;block&gt;/dev/sdf1&lt;/block&gt;
&lt;/source&gt;
&lt;/hostdev&gt;
...
</pre>
<pre>
...
&lt;hostdev mode='capabilities' type='misc'&gt;
&lt;source&gt;
&lt;char&gt;/dev/input/event3&lt;/char&gt;
&lt;/source&gt;
&lt;/hostdev&gt;
...
</pre>
<dl>
<dt><code>hostdev</code></dt>
<dd>The <code>hostdev</code> element is the main container for describing
host devices. For block/character device passthrough <code>mode</code> is
always "capabilities" and <code>type</code> is "block" for a block
device and "char" for a character device.
</dd>
<dt><code>source</code></dt>
<dd>The source element describes the device as seen from the host.
For block devices, the path to the block device in the host
OS is provided in the nested "block" element, while for character
devices the "char" element is used
</dd>
</dl>
<h4><a name="elementsRedir">Redirected devices</a></h4>
<p>