Comment 7 for bug 1418221

The patch mentioned in comment #1 is hackish, and does not address the problem completely.
Libvirt seems to fail on ubuntu because it does not find an appropriate emulator for ppc64le in course of capabilities probe:

# virsh capabilities

...[snip]:
<guest>
    <os_type>hvm</os_type>
    <arch name='ppc64'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-ppc64</emulator>
      <machine maxCpus='256'>pseries</machine>
      <machine maxCpus='1'>ref405ep</machine>
      ....
</guest>.
<guest>
    <os_type>hvm</os_type>
    <arch name='ppcemb'>
 ...
</guest>

However, when I run upstream libvirt on another little endian distro such as Fedora 21, I explicitly see a listing for 'ppc64le' guest :
<guest>
    <os_type>hvm</os_type>
    <arch name='ppc64'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-ppc64</emulator>
      <machine maxCpus='256'>pseries</machine>
      <machine maxCpus='1'>ref405ep</machine>
      <machine maxCpus='1'>virtex-ml507</machine>
      <machine maxCpus='32'>ppce500</machine>
     ....
</guest>
 <guest>
    <os_type>hvm</os_type>
    <arch name='ppc64le'> ==> See that an explicit emulator is listed under '<emulator>' tag
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-kvm</emulator>
      <machine maxCpus='256'>pseries</machine>
      <machine maxCpus='1'>ref405ep</machine>
      <machine maxCpus='1'>virtex-ml507</machine>
      <machine maxCpus='32'>ppce500</machine>
     ...
</guest>
<guest>
    <os_type>hvm</os_type>
    <arch name='ppcemb'>
 ...
</guest>

I'm investigating why virsh capabilities omits a guest listing for ppc64el arch on Ubuntu.