On Thu, 2017-05-18 at 11:09 +0200, Ján Tomko wrote:
Add an attribute to control extended interrupt mode. https://bugzilla.redhat.com/show_bug.cgi?id=1451282
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@@ -7436,6 +7436,16 @@ qemu-kvm -net nic,model=? /dev/null <span class="since">Since 3.4.0</span> (QEMU/KVM only) </p> </dd> + <dt><code>eim</code></dt> + <dd> + <p> + The <code>eim</code> attribute with possible values + <code>on</code> and <code>off</code> can be used to + turn on extended interrupt mode. In combination with intremap + and split I/O APIC, this allows for more vCPUs to be used. + <span class="since">Since 3.4.0</span> (QEMU/KVM only) + </p> + </dd> </dl> </dd> </dl>
Actually, the documentation could use some work too. How about: The <code>eim</code> attribute (with possible values <code>on</code> and <code>off</code>) can be used to configure Extended Interrupt Mode. A q35 domain with split I/O APIC (as described in <a href="#elementsFeatures">hypervisor features</a>), and both interrupt remapping and EIM turned on for the IOMMU, will be able to use more than 255 vCPUs. <span class="since">Since 3.4.0</span> (QEMU/KVM only) -- Andrea Bolognani / Red Hat / Virtualization