The first step to creating a virtual machine in bhyve is configuring the host system. Load the bhyve kernel module called vmm. Create a tap interface for the network device in the virtual machine to attach to. Optionally create a bridge interface and add the tap interface as well as the physical interface as members to allow the virtual machine to have access to the network.

Create a file to use as the virtual disk for the guest machine.

Download an installation image of FreeBSD to install.

FreeBSD comes with an example script for running a virtual machine in bhyve. The script will start the virtual machine and run it in a loop, so it will automatically restart if it crashes. The script takes a number of options to control the configuration of the machine. -c controls the number of virtual CPUs. -m limits the amount of memory available to the guest. -t defines which tap device to use. -d indicates which disk image to use. -i tells bhyve to boot from the CD image instead of the disk, and -I defines which CD image to use. Finally the last parameter is the name of the virtual machine, used to track the running machines. Start the virtual machine in installation mode:

The system will boot and start the installer. After installing a system in the virtual machine, when the system asks about dropping in to a shell at the end of the installation, choose Yes. A small change needs to be made to make the system start with a serial console. Edit /etc/ttys and replace the existing console line with:

Reboot the virtual machine. In bhyve, a reboot causes bhyve to exit. However the vmrun.sh script runs bhyve in a loop and will automatically restart it. When this happens, choose the reboot option from the boot loader menu, and this will escape the loop. Now the guest can be started from the virtual disk:

Create a file to use as the virtual disk for the guest machine.

Starting a virtual machine with bhyve is a two step process. First a kernel must be loaded, then the guest can be started. sysutils/grub2-bhyve is used to load the Linux® kernel. Create a device.map that grub will use to map the virtual devices to the files on the host system:

Use sysutils/grub2-bhyve to load the Linux® kernel from the ISO image:

This will start grub. If the installation CD contains a grub.cfg then a menu will be displayed. If not, the location of the vmlinuz and initrd files must be manually entered:

Now that the Linux® kernel is loaded, the guest can be started:

The system will boot and start the installer. After installing a system in the virtual machine, reboot the virtual machine. This will cause bhyve to exit. The instance of the virtual machine needs to be destroyed before it can be started again:

Now the guest can be started directly from the virtual disk:

Linux® will now boot in the virtual machine and eventually present you with the login prompt. Login and use the virtual machine, when you are finished, reboot the virtual machine to exit bhyve. Destroy the virtual machine instance:

It is advantageous to wrap the bhyve console in a session management tool such as sysutils/tmux or sysutils/screen in order to detach and reattach to the console. It is also possible to have the console of bhyve be a null modem device that can be accessed with cu. Load the nmdm kernel module, and replace -l com1,stdio with -l com1,/dev/nmdm0A. The /dev/nmdm devices are created automatically as needed, each is a pair, /dev/nmdm1A and /dev/nmdm1B corresponding to the two ends of the null modem cable. See nmdm(4) for more information.

A device node is created in /dev/vmm for each virtual machine. This allows the administrator to easily see a list of the running virtual machines:

Virtual machines can be destroyed using bhyvectl:

In order to make the system able to start bhyve guests at boot time, the following configurations must be made in the specified files: