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Re: [libvirt] USB2 controllers & domain XML



  Hi,

  - Since the companion controllers have associated PCI addresses,
    we must represent them explicitly in the XML, so it is clear
    to apps what PCI slots/functions are used.

Hmm.  Do we have to?

Usually the individual pci functions of multifunction devices are not fully independent of each other. It is a single device with multiple interfaces. I would try to present the *device* in libvirt xml, not the *interfaces*.

[ Yes, you can bundle multiple virtio devices as multifunction device
  into a single pci slot to overcome the slot number limit.  That isn't
  how pci functions are usually used on real hardware though. ]

   5. USB companion controllers use type='usb' too, but with an
      extra 'master' attribute to associate them


        <controller type='usb' index='0' model='ich9-ehci'>
          <address type='pci' domain='0' bus='0' slot='4' function='7'/>
        </controller>
        <controller type='usb' index='0' model='ich9-ehci1'>
          <master startport='0'/>
          <address type='pci' domain='0' bus='0' slot='4' function='1'/>
        </controller>
>         [ ... ]

  <controller type='usb' index='0' model='ich9-ehci-with-companions'>
    <address type='pci' domain='0' bus='0' slot='4' />
  </controller>

?

cheers,
  Gerd


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