Bug 1154152

I just tested with Nova git master

  $ git describe
  2014.2-1435-gbb16f77

And, seems like it *does* allow me to boot a Nova instance successfully with hw:numa_nodes=0, with a Nova guest XML like that[*]. But talking with Daniel Berrnage and Nikola Dipanov on IRC:

  <danpb> hmm, i'm not convinced we should allow nodes=0 at all
  <danpb> we should default  1 node if nothing is specified
  <danpb> We should refuse a vlaue of 0, in case we wish to make use 
   of that as a special value at a later date
  <danpb> we don't want people relying on  numa_nodes=0  accidentally
   working for them now
  <nikola> danpb, correct


I filed an upstream bug with a link to this bug

  https://bugs.launchpad.net/nova/+bug/1402709 -- Report an error when booting an instance with a flavor which has NUMA nodes is set to 0 (hw:numa_nodes=0)


[*] Nova guest XML with an instance booted with hw:numa_nodes=0
-----------------------------------------------------------------------------
<domain type='kvm' id='3'>
  <name>instance-00000004</name>
  <uuid>593f8388-ac9c-4673-b1c7-aa49b1ce83f0</uuid>
  <metadata>
    <nova:instance xmlns:nova="http://openstack.org/xmlns/libvirt/nova/1.0">
      <nova:package version="2015.1"/>
      <nova:name>cirrvm4</nova:name>
      <nova:creationTime>2014-12-15 14:41:43</nova:creationTime>
      <nova:flavor name="m1.tiny">
        <nova:memory>512</nova:memory>
        <nova:disk>1</nova:disk>
        <nova:swap>0</nova:swap>
        <nova:ephemeral>0</nova:ephemeral>
        <nova:vcpus>1</nova:vcpus>
      </nova:flavor>
      <nova:owner>
        <nova:user uuid="0d5623bdae83445ba3a6209ea849fffe">admin</nova:user>
        <nova:project uuid="f9ecf22769cf4ab98543f5ade1454664">admin</nova:project>
      </nova:owner>
      <nova:root type="image" uuid="5bc9a92b-6cda-4916-9bb0-dd9751880cde"/>
    </nova:instance>
  </metadata>
  <memory unit='KiB'>524288</memory>
  <currentMemory unit='KiB'>524288</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='0-3'/>
    <emulatorpin cpuset='0-3'/>
  </cputune>
  <numatune>
    <memory mode='strict' nodeset='0'/>
    <memnode cellid='0' mode='strict' nodeset='0'/>
  </numatune>
  <resource>
    <partition>/machine</partition>
  </resource>
  <sysinfo type='smbios'>
    <system>
      <entry name='manufacturer'>OpenStack Foundation</entry>
      <entry name='product'>OpenStack Nova</entry>
      <entry name='version'>2015.1</entry>
      <entry name='serial'>bf6b5391-2390-df4f-b3dc-aa80d05468bb</entry>
      <entry name='uuid'>593f8388-ac9c-4673-b1c7-aa49b1ce83f0</entry>
    </system>
  </sysinfo>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.2'>hvm</type>
    <boot dev='hd'/>
    <smbios mode='sysinfo'/>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <cpu>
    <topology sockets='1' cores='1' threads='1'/>
    <numa>
      <cell id='0' cpus='0' memory='524288' unit='KiB'/>
    </numa>
  </cpu>
  <clock offset='utc'>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='none'/>
      <source file='/home/kashyapc/src/cloud/data/nova/instances/593f8388-ac9c-4673-b1c7-aa49b1ce83f0/disk'/>
      <backingStore type='file' index='1'>
        <format type='raw'/>
        <source file='/home/kashyapc/src/cloud/data/nova/instances/_base/03a663c2a1c649fe0854f01c82c0ddb3871cf691'/>
        <backingStore/>
      </backingStore>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw' cache='none'/>
      <source file='/home/kashyapc/src/cloud/data/nova/instances/593f8388-ac9c-4673-b1c7-aa49b1ce83f0/disk.config'/>
      <backingStore/>
      <target dev='hdd' bus='ide'/>
      <readonly/>
      <alias name='ide0-1-1'/>
      <address type='drive' controller='0' bus='1' target='0' unit='1'/>
    </disk>
    <controller type='usb' index='0'>
      <alias name='usb0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'>
      <alias name='pci.0'/>
    </controller>
    <controller type='ide' index='0'>
      <alias name='ide0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <interface type='bridge'>
      <mac address='fa:16:3e:79:6c:b8'/>
      <source bridge='qbr7584d9fb-e1'/>
      <target dev='tap7584d9fb-e1'/>
      <model type='virtio'/>
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </interface>
    <serial type='file'>
      <source path='/home/kashyapc/src/cloud/data/nova/instances/593f8388-ac9c-4673-b1c7-aa49b1ce83f0/console.log'/>
      <target port='0'/>
      <alias name='serial0'/>
    </serial>
    <serial type='pty'>
      <source path='/dev/pts/19'/>
      <target port='1'/>
      <alias name='serial1'/>
    </serial>
    <console type='file'>
      <source path='/home/kashyapc/src/cloud/data/nova/instances/593f8388-ac9c-4673-b1c7-aa49b1ce83f0/console.log'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <memballoon model='virtio'>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
      <stats period='10'/>
    </memballoon>
  </devices>
  <seclabel type='dynamic' model='selinux' relabel='yes'>
    <label>system_u:system_r:svirt_t:s0:c79,c658</label>
    <imagelabel>system_u:object_r:svirt_image_t:s0:c79,c658</imagelabel>
  </seclabel>
</domain>
-----------------------------------------------------------------------------

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