[Bug 1304107] Re: Libvirt error launching instance - Device 'virtio-net-pci' could not be initialized

[Daniel Berrange]

Ok that log is interesting as it shows that Ubuntu have re-named the
QEMU machine types

 ...  -machine trusty,accel=tcg,usb=off ...

See 'trusty' is the machine type there instead of the more usual "pc-
i440fx-1.6"

This unfortunately breaks the ability of libvirt to figure out what type
of base board is used by the VM - it can't distinguish i440fx from q35.
I'm guessing Ubuntu was probably inspired by the fact that we did a
similar thing in RHEL-6, replacing 'pc' with 'rhel-6.1.0'.

The recommendation for distros who want to customize the machine types
without breaking libvirt is to *not* replace the entire machine type
name, but instead to just replace the upstream version number with a
distro specific suffix.

eg  change 'pc-i440fx-1.6' to be 'pc-i440fx-trusty'.  That way libvirt
can still see that this is an i440fx machine type and do the right thing
with PCI address validation.

As a reference point, RHEL7 does this correctly now too, using  'pc-
i440fx-rhel7.0.0' as machine type name.

Unfortunately there's nothing OpenStack Nova can do to workaround this.
Either Ubuntu have to change their QEMU machine type name as
illustrated, to maintain the right prefix, or they'll have to hack their
libvirt build to cope with the bare name 'trusty' :-(

** Also affects: qemu (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1304107

Title:
  Libvirt error launching instance - Device 'virtio-net-pci' could not
  be initialized

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