Libvirt: não há como usar um ônibus isa?

Question

Eu encontrei uma maneira de executar o Windows95 (estou um pouco nostálgico e uso sistemas antigos para testes) com o qemu

 /usr/bin/qemu-system-i386  -L pc-bios -m 64 -hda /home/user/.local/libvirt/images/win95.img  -net nic,model=ne2k_isa -net user -soundhw sb16 --enable-kvm -cpu qemu32 -M isapc

Com esta linha funciona bem, execute com baixo uso de cpu.

Quero agora importar no libvirt

Eu crio o arquivo .args

LC_ALL=C 
PATH=/bin:/usr/bin:/sbin:/usr/sbin
HOME=/home/user
USER=user
LOGNAME=user qemu-system-i386  -L pc-bios -M isapc -m 64 -hda win95.img -net nic,model=ne2k_isa -net user -soundhw sb16 --enable-kvm -cpu qemu32

Converter ...

virsh domxml-from-native qemu-argv file.args  > win95.xml

Mas quando tento correr ...

virsh create win95.xml

error: Failed to create domain from win95.xml
error: XML error: No PCI buses available

Este é o arquivo xml: nenhuma maneira de obter isa na libvirt?

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>unnamed</name>
  <uuid>37b8dc38-63bb-4206-94f8-26f47bce21b9</uuid>
  <memory unit='KiB'>65536</memory>
  <currentMemory unit='KiB'>65536</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type machine='isapc'>hvm</type>
  </os>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-i386</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/home/user/.local/libvirt/images/win95.img'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0'/>
    <controller type='ide' index='0'/>
    <interface type='user'>
      <mac address='52:54:00:d8:35:b3'/>
      <model type='ne2k_isa'/>
    </interface>
    <graphics type='sdl'/>
    <sound model='sb16'/>
    <video>
      <model type='cirrus' vram='16384' heads='1'/>
    </video>
    <memballoon model='none'/>
  </devices>
  <qemu:commandline>
    <qemu:arg value='-L'/>
    <qemu:arg value='pc-bios'/>
  </qemu:commandline>
</domain>