[libvirt] Cannot add iothreads label in libvirt xml configuration file

Weiwei Jia harrynjit at gmail.com
Fri Dec 23 23:12:28 UTC 2016

On Thu, Dec 22, 2016 at 5:01 PM, John Ferlan <jferlan at redhat.com> wrote:
> On 12/21/2016 12:11 PM, Weiwei Jia wrote:
>> Hi,
>> I cannot add iothreads
>> (https://libvirt.org/formatdomain.html#elementsIOThreadsAllocation) in
>> the libvirt xml configuration file. Once I add
>> "<iothreads>4</iothreads>" and other related config for IOthreads into
>> the libvirt xml configuration file with virsh command and save it,
>> these iothreads related configuration will disappear after I open
>> libvirt xml configuration file again for double-check.
>> The current libvirt xml configuration file is like following.
> If I try to just cut-n-paste the following xml into a buffer, then run
> virsh define kvm1.xml, I get:
> error: Failed to define domain from kvm1.xml
> error: Cannot check QEMU binary /usr/bin/kvm-spice: No such file or
> directory
> In order to support iothreads, it requires an "-object iothread"... The
> "shortest" command line using qemu-kvm would be "qemu-kvm -object
> iothread,id=xxx1", so you could try the same with that
> /usr/bin/kvm-spice image and see what you get.
> You could try to figure out from the
> /var/cach/libvirt/qemu/capabilities/*.xml files whether or not the
> "iothread" object exists... I would think though that the reason why
> this is failing for you is that the kvm-spice emulator doesn't have the
> required capability (I forget if there's a magic incantation to ask the
> emulator image what it supports, especially for objects).

Thanks for your suggestions. I have tried your way and the results
tell me there are some problems with my libvirt xml configuration
file. I think I need to fix it with correct libvirt xml configuration

Weiwei Jia

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