docs: Add documentation for compat mode.

Add documentation to explain how compat-mode can be invoked with libvirt
running on PowerPC architecture.
It also mentions that this change is available libvirt 1.2.11 onwards.

Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Prerna Saxena 2014-11-04 23:00:36 +05:30 committed by Michal Privoznik
parent 1e91174228
commit 9265fd19b6

View File

@ -1047,7 +1047,20 @@
(such as CPUID level) that don't work. Until these issues are fixed,
it's a good idea to avoid using <code>host-model</code> and use
<code>custom</code> mode with just the CPU model from host
capabilities XML.</dd>
capabilities XML.
<span class="since">(Since 1.2.11)</span>. PowerISA allows
processors to run VMs in binary compatibility mode supporting an
older version of ISA. Libvirt on PowerPC architecture uses the
<code>host-model</code> to signify a guest mode CPU running in
binary compatibility mode. Example:
When a user needs a power7 VM to run in compatibility mode
on a Power8 host, this can be described in XML as follows :
<pre>
&lt;cpu mode='host-model'&gt;
&lt;model&gt;power7&lt;/model&gt;
&lt;/cpu&gt;
...</pre>
</dd>
<dt><code>host-passthrough</code></dt>
<dd>With this mode, the CPU visible to the guest should be exactly
the same as the host CPU even in the aspects that libvirt does not