[Libvir] <model>e1000</model> - Specifying model in XML Configs

[Richard W.M. Jones]

On Mon, Apr 07, 2008 at 10:51:56PM +0100, Henri Cook wrote:
> I just tried to port a few customers over to this libvirt setup i'm
> hoping to run and I couldn't get their machines started because there's
> no mechanism to specify a model in the XML!
> 
> I know redhat have changed KVM's default driver to e1000, which I think
> is the one I like the most and almost if not all of my VMs use. Ubuntu
> haven't done that yet however!
> 
> Is there a model directive in the latest version? In the works? Just so
> I know which solution I should pursue (updating libvirt or harassing
> ubuntu to change the default)

There isn't a way to select the model, but there ought to be.  In KVM
64 the following NIC models are supported:

  i82551 i82557b i82559er ne2k_pci pcnet rtl8139 e1000 virtio

Part of the problem with implementing this will be validating the
model (unless we just pass the model string directly to qemu which
could lead to errors).  The documentation suggests running qemu with
'-net nic,model=?' to list the models, and there is code in
qemu/hw/pci.c to implement this, but it just doesn't work for me.

  $ qemu-kvm -net nic,model=?
  
  [ prints full help because of the missing hda parameter ]
  
  $ qemu-kvm -net nic,model=? hda=/dev/null
  open /dev/kvm: Permission denied
  Could not initialize KVM, will disable KVM support
  Warning: vlan 0 is not connected to host network
  qemu: could not open disk image hda=/dev/null
  
  $ qemu-kvm -net nic,model=? hda=/dev/zero
  open /dev/kvm: Permission denied
  Could not initialize KVM, will disable KVM support
  Warning: vlan 0 is not connected to host network
  qemu: could not open disk image hda=/dev/zero
  
  $ touch /tmp/file
  $ qemu-kvm -net nic,model=? hda=/tmp/file
  open /dev/kvm: Permission denied
  Could not initialize KVM, will disable KVM support
  Warning: vlan 0 is not connected to host network
  qemu: could not open disk image hda=/tmp/file
  
  $ dd if=/dev/zero of=/tmp/file bs=1024 count=1024
  1024+0 records in
  1024+0 records out
  1048576 bytes (1.0 MB) copied, 0.00765395 s, 137 MB/s
  $ qemu-kvm -net nic,model=? hda=/tmp/file
  open /dev/kvm: Permission denied
  Could not initialize KVM, will disable KVM support
  Warning: vlan 0 is not connected to host network
  qemu: could not open disk image hda=/tmp/file

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
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