Bhyve driver

Bhyve is a FreeBSD hypervisor. It first appeared in FreeBSD 10.0. However, it's recommended to keep tracking FreeBSD 10-STABLE to make sure all new features of bhyve are supported. In order to enable bhyve on your FreeBSD host, you'll need to load the vmm kernel module. Additionally, if_tap and if_bridge modules should be loaded for networking support.

Additional information on bhyve could be obtained on bhyve.org.

Connections to the Bhyve driver

The libvirt bhyve driver is a single-instance privileged driver. Some sample connection URIs are:

bhyve:///system                     (local access)
bhyve+unix:///system                (local access)
bhyve+ssh://root@example.com/system (remote access, SSH tunnelled)

Example guest domain XML configurations

Example config

The bhyve driver in libvirt is in its early stage and under active development. So it supports only limited number of features bhyve provides. All the supported features could be found in this sample domain XML.

A limitation that is not obvious from this sample domain XML is that currently only a single network and a single disk device are supported for each domain (as PCI slot allocation code in libvirt bhyve driver is yet to be implemented).

<domain type='bhyve'>
  <name>bhyve</name>
  <uuid>df3be7e7-a104-11e3-aeb0-50e5492bd3dc</uuid>
    <memory>219136</memory>
    <currentMemory>219136</currentMemory>
    <vcpu>1</vcpu>
    <os>
       <type>hvm</type>
    </os>
    <features>
      <apic/>
      <acpi/>
    </features>
    <clock offset='utc'/>
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>destroy</on_crash>
    <devices>
      <disk type='file'>
        <driver name='file' type='raw'/>
        <source file='/path/to/bhyve_freebsd.img'/>
        <target dev='hda' bus='sata'/>
      </disk>
      <interface type='bridge'>
        <model type='virtio'/>
        <source bridge="virbr0"/>
      </interface>
    </devices>
</domain>

Guest usage / management

Connecting to a guest console

Guest console connection is supported through the nmdm device. It could be enabled by adding the following to the domain XML (Since 1.2.4):

  ...
  <devices>
    <serial type="nmdm">
      <source master="/dev/nmdm0A" slave="/dev/nmdm0B"/>
    </serial>
  </devices>
  ...

Make sure to load the nmdm kernel module if you plan to use that.

Then virsh console command can be used to connect to the text console of a guest.

NB: Some versions of bhyve have a bug that prevents guests from booting until the console is opened by a client. This bug was fixed in FreeBSD r262884. If an older version is used, one either has to open a console manually with virsh console to let a guest boot or start a guest using:

start --console domname

Converting from domain XML to Bhyve args

The virsh domxml-to-native command can preview the actual bhyve commands that will be executed for a given domain. It outputs two lines, the first line is a bhyveload command and the second is a bhyve command.

Please note that the virsh domxml-to-native doesn't do any real actions other than printing the command, for example, it doesn't try to find a proper TAP interface and create it, like what is done when starting a domain; and always returns tap0 for the network interface. So if you're going to run these commands manually, most likely you might want to tweak them.

# virsh -c "bhyve:///system"  domxml-to-native --format bhyve-argv --xml /path/to/bhyve.xml
/usr/sbin/bhyveload -m 214 -d /home/user/vm1.img vm1
/usr/sbin/bhyve -c 2 -m 214 -A -I -H -P -s 0:0,hostbridge -s 3:0,virtio-net,tap0,mac=52:54:00:5d:74:e3 -s 2:0,virtio-blk,/home/user/vm1.img -s 1,lpc -l com1,/dev/nmdm0A vm1