Re: [libvirt] [PATCH v2 2/6] cpu: Optionally forbid fallback CPU models

In case a hypervisor doesn't support the exact CPU model requested by a domain XML, we automatically fallback to a closest CPU model the hypervisor supports (and make sure we add/remove any additional features if needed). This patch adds 'fallback' attribute to model element, which can be used to disable this automatic fallback. --- Notes: Version 2: - grammar

+++ b/docs/formatdomain.html.in @@ -559,7 +559,7 @@ <pre> ... &lt;cpu match='exact'&gt; - &lt;model&gt;core2duo&lt;/model&gt; + &lt;model fallback='allow'&gt;core2duo&lt;/model&gt; &lt;vendor&gt;Intel&lt;/vendor&gt; &lt;topology sockets='1' cores='2' threads='1'/&gt; &lt;feature policy='disable' name='lahf_lm'/&gt; @@ -609,7 +609,15 @@ <dd>The content of the <code>model</code> element specifies CPU model requested by the guest. The list of available CPU models and their definition can be found in <code>cpu_map.xml</code> file installed - in libvirt's data directory.</dd> + in libvirt's data directory. If a hypervisor is not able to use the + exact CPU model, libvirt automatically falls back to a closest model + supported by the hypervisor while maintaining the list of CPU + features. <span class="since">Since 0.9.10</span>, an optional + <code>fallback</code> attribute can be used to forbid this behavior, + in which case an attempt to start a domain requesting unsupported

+ CPU model will fail. Supported values for <code>fallback</code> + attribute are: <code>allow</code> (this is the default), and + <code>forbid</code>.</dd>