odd bhyve <-> ubuntu 14.04 problem

[Peter Grehan]

Hi John,

> I upgraded the host from freebsd-10-RC3 to 10.1-R and after that
> upgraded bhyve to grub2-bhyve-0.30 today and since then I've found that
> when booting ubuntu 14.04.1 LTS guests, the ethernet interface (ethN
> where N is a number) is now variable. This is an issue because if I stop
> a VM and say reboot the host, I have to hack about with the VM instead
> of just booting it.
>
> Previously the VM always saw the virtual network interface as eth0. Now,
> it's anything but that. bhyve has been upgraded, the VM hasn't. How can
> I control this behaviour? I want eth0 to remain as eth0. These are all
> VMs that were eth0 before the bhyve upgrade. It doesn't appear to matter
> what tap interface is used. I don't have this issue with freebsd guests
> on the freebsd host, just ubuntu 14.04.1 LTS.
>
> I define the bridge and 9 tap interfaces at boot, in case this is
> relevant. Please can anyone shed some light?

  Was the name of the VM changed when doing the upgrade ? If so, that 
will modify the MAC address, which confuses Ubuntu.

  The MAC addresses generated for an interface are derived from an md5 
hash of the PCI slot/function and VM name, so they should be unique for 
each port and VM on a system. If the VM name is changed, or the slot 
configuration of a virtio-net device is changed, the MAC will also be 
changed.

  bhyve does provide the ability to set the MAC address for an 
interface, but granted this isn't available as an option with vmrun.sh :(

later,

Peter.