Chapter 24. Virtualization

The first step in installing FreeBSD on Parallels is to create a new virtual machine for installing FreeBSD.

Choose Install Windows or another OS from a DVD or image file and proceed.

Select the FreeBSD image file.

Choose Other as operating system.

Name the virtual machine and check Customize settings before installation

When the configuration window pops up, go to Hardware tab, choose Boot order, and click Advanced. Then, choose EFI 64-bit as BIOS.

Click OK, close the configuration window, and click Continue.

The virtual machine will automatically boot. Install FreeBSD following the general steps.

After FreeBSD has been successfully installed on macOS® X with Parallels, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.

The first step is to start VMware Fusion which will load the Virtual Machine Library. Click +→New to create the virtual machine:

This will load the New Virtual Machine Assistant. Choose Create a custom virtual machine and click Continue to proceed:

Select Other as the Operating System and either FreeBSD X or FreeBSD X 64-bit, as the Version when prompted:

Choose the firmware(UEFI is recommended):

Choose Create a new virtual disk and click Continue:

Check the configuration and click Finish:

Choose the name of the virtual machine and the directory where it should be saved:

Press command+E to open virtual machine settings and click CD/DVD:

Choose FreeBSD ISO image or from a CD/DVD:

Start the virtual machine:

Install FreeBSD as usual:

Once the install is complete, the settings of the virtual machine can be modified, such as memory usage and the number of CPUs the virtual machine will have access to:

The status of the CD-ROM device. Normally the CD/DVD/ISO is disconnected from the virtual machine when it is no longer needed.

The last thing to change is how the virtual machine will connect to the network. To allow connections to the virtual machine from other machines besides the host, choose Connect directly to the physical network (Bridged). Otherwise, Share the host’s internet connection (NAT) is preferred so that the virtual machine can have access to the Internet, but the network cannot access the virtual machine.

After modifying the settings, boot the newly installed FreeBSD virtual machine.

After FreeBSD has been successfully installed on macOS® X with VMware Fusion, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.

VirtualBox™ is available as a FreeBSD package or port in emulators/virtualbox-ose. The port can be installed using these commands:

One useful option in the port’s configuration menu is the GuestAdditions suite of programs. These provide a number of useful features in guest operating systems, like mouse pointer integration (allowing the mouse to be shared between host and guest without the need to press a special keyboard shortcut to switch) and faster video rendering, especially in Windows® guests. The guest additions are available in the Devices menu, after the installation of the guest is finished.

A few configuration changes are needed before VirtualBox™ is started for the first time. The port installs a kernel module in /boot/modules which must be loaded into the running kernel:

To ensure the module is always loaded after a reboot, add this line to /boot/loader.conf:

To use the kernel modules that allow bridged or host-only networking, add this line to /etc/rc.conf and reboot the computer:

The vboxusers group is created during installation of VirtualBox™. All users that need access to VirtualBox™ will have to be added as members of this group. pw can be used to add new members:

The default permissions for /dev/vboxnetctl are restrictive and need to be changed for bridged networking:

To make this permissions change permanent, add these lines to /etc/devfs.conf:

To launch VirtualBox™, type from an Xorg session:

For more information on configuring and using VirtualBox™, refer to the official website. For FreeBSD-specific information and troubleshooting instructions, refer to the relevant page in the FreeBSD wiki.

VirtualBox™ can be configured to pass USB devices through to the guest operating system. The host controller of the OSE version is limited to emulating USB 1.1 devices until the extension pack supporting USB 2.0 and 3.0 devices becomes available on FreeBSD.

For VirtualBox™ to be aware of USB devices attached to the machine, the user needs to be a member of the operator group.

Then, add the following to /etc/devfs.rules, or create this file if it does not exist yet:

To load these new rules, add the following to /etc/rc.conf:

Then, restart devfs:

Restart the login session and VirtualBox™ for these changes to take effect, and create USB filters as necessary.

Access to the host DVD/CD drives from guests is achieved through the sharing of the physical drives. Within VirtualBox™, this is set up from the Storage window in the Settings of the virtual machine. If needed, create an empty IDECD/DVD device first. Then choose the Host Drive from the popup menu for the virtual CD/DVD drive selection. A checkbox labeled Passthrough will appear. This allows the virtual machine to use the hardware directly. For example, audio CDs or the burner will only function if this option is selected.

In order for users to be able to use VirtualBox™DVD/CD functions, they need access to /dev/xpt0, /dev/cdN, and /dev/passN. This is usually achieved by making the user a member of operator. Permissions to these devices have to be corrected by adding these lines to /etc/devfs.conf:

The first step to creating a virtual machine in bhyve is configuring the host system. First, load the bhyve kernel module:

Then, create a tap interface for the network device in the virtual machine to attach to. In order for the network device to participate in the network, also create a bridge interface containing the tap interface and the physical interface as members. In this example, the physical interface is igb0:

Create a file to use as the virtual disk for the guest machine. Specify the size and name of the virtual disk:

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. The last parameter is the name of the virtual machine, used to track the running machines. This example starts the virtual machine in installation mode:

The virtual machine 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.

Reboot the virtual machine. While rebooting the virtual machine causes bhyve to exit, 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 in order to escape the loop. Now the guest can be started from the virtual disk:

In order to boot operating systems other than FreeBSD, the sysutils/grub2-bhyve port must be first installed.

Next, 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. The Linux® kernel is loaded with sysutils/grub2-bhyve. 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, a menu will be displayed. If not, the vmlinuz and initrd files must be located and loaded manually:

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. Load the kernel:

Boot the virtual machine:

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:

In addition to bhyveload and grub-bhyve, the bhyve hypervisor can also boot virtual machines using the UEFI userspace firmware. This option may support guest operating systems that are not supported by the other loaders.

In order to make use of the UEFI support in bhyve, first obtain the UEFI firmware images. This can be done by installing sysutils/bhyve-firmware port or package.

With the firmware in place, add the flags -l bootrom,/path/to/firmware to your bhyve command line. The actual bhyve command may look like this:

sysutils/bhyve-firmware also contains a CSM-enabled firmware, to boot guests with no UEFI support in legacy BIOS mode:

The UEFI firmware support is particularly useful with predominantly graphical guest operating systems such as Microsoft Windows®.

Support for the UEFI-GOP framebuffer may also be enabled with the -s 29,fbuf,tcp=0.0.0.0:5900 flags. The framebuffer resolution may be configured with w=800 and h=600, and bhyve can be instructed to wait for a VNC connection before booting the guest by adding wait. The framebuffer may be accessed from the host or over the network via the VNC protocol. Additionally, -s 30,xhci,tablet can be added to achieve precise mouse cursor synchronization with the host.

The resulting bhyve command would look like this:

Note, in BIOS emulation mode, the framebuffer will cease receiving updates once control is passed from firmware to guest operating system.

If ZFS is available on the host machine, using ZFS volumes instead of disk image files can provide significant performance benefits for the guest VMs. A ZFS volume can be created by:

When starting the VM, specify the ZFS volume as the disk drive:

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. To do this, load the nmdm kernel module and replace -l com1,stdio with -l com1,/dev/nmdm0A. The /dev/nmdm devices are created automatically as needed, where each is a pair, corresponding to the two ends of the null modem cable (/dev/nmdm0A and /dev/nmdm0B). 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:

A specified virtual machine can be destroyed using bhyvectl:

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

To run the Xen™ hypervisor on a host, certain hardware functionality is required. Hardware virtualized domains require Extended Page Table (EPT) and Input/Output Memory Management Unit (IOMMU) support in the host processor.

Users of FreeBSD 11 should install the emulators/xen-kernel47 and sysutils/xen-tools47 packages that are based on Xen version 4.7. Systems running on FreeBSD-12.0 or newer can use Xen 4.11 provided by emulators/xen-kernel411 and sysutils/xen-tools411, respectively.

Configuration files must be edited to prepare the host for the Dom0 integration after the Xen packages are installed. An entry to /etc/sysctl.conf disables the limit on how many pages of memory are allowed to be wired. Otherwise, DomU VMs with higher memory requirements will not run.

Another memory-related setting involves changing /etc/login.conf, setting the memorylocked option to unlimited. Otherwise, creating DomU domains may fail with Cannot allocate memory errors. After making the change to /etc/login.conf, run cap_mkdb to update the capability database. See Resource Limits for details.

Add an entry for the Xen™ console to /etc/ttys:

Selecting a Xen™ kernel in /boot/loader.conf activates the Dom0. Xen™ also requires resources like CPU and memory from the host machine for itself and other DomU domains. How much CPU and memory depends on the individual requirements and hardware capabilities. In this example, 8 GB of memory and 4 virtual CPUs are made available for the Dom0. The serial console is also activated and logging options are defined.

The following command is used for Xen 4.7 packages:

For Xen versions 4.11 and higher, the following command should be used instead:

Activate the xencommons service during system startup:

These settings are enough to start a Dom0-enabled system. However, it lacks network functionality for the DomU machines. To fix that, define a bridged interface with the main NIC of the system which the DomU VMs can use to connect to the network. Replace em0 with the host network interface name.

Restart the host to load the Xen™ kernel and start the Dom0.

After successfully booting the Xen™ kernel and logging into the system again, the Xen™ management tool xl is used to show information about the domains.

The output confirms that the Dom0 (called Domain-0) has the ID 0 and is running. It also has the memory and virtual CPUs that were defined in /boot/loader.conf earlier. More information can be found in the Xen™ Documentation. DomU guest VMs can now be created.

Unprivileged domains consist of a configuration file and virtual or physical hard disks. Virtual disk storage for the DomU can be files created by truncate(1) or ZFS volumes as described in “Creating and Destroying Volumes”. In this example, a 20 GB volume is used. A VM is created with the ZFS volume, a FreeBSD ISO image, 1 GB of RAM and two virtual CPUs. The ISO installation file is retrieved with fetch(1) and saved locally in a file called freebsd.iso.

A ZFS volume of 20 GB called xendisk0 is created to serve as the disk space for the VM.

The new DomU guest VM is defined in a file. Some specific definitions like name, keymap, and VNC connection details are also defined. The following freebsd.cfg contains a minimum DomU configuration for this example:

These lines are explained in more detail:

After the file has been created with all the necessary options, the DomU is created by passing it to xl create as a parameter.

The output of xl list confirms that the DomU has been created.

To begin the installation of the base operating system, start the VNC client, directing it to the main network address of the host or to the IP address defined on the vnclisten line of freebsd.cfg. After the operating system has been installed, shut down the DomU and disconnect the VNC viewer. Edit freebsd.cfg, removing the line with the cdrom definition or commenting it out by inserting a # character at the beginning of the line. To load this new configuration, it is necessary to remove the old DomU with xl destroy, passing either the name or the id as the parameter. Afterwards, recreate it using the modified freebsd.cfg.

The machine can then be accessed again using the VNC viewer. This time, it will boot from the virtual disk where the operating system has been installed and can be used as a virtual machine.

This section contains basic information in order to help troubleshoot issues found when using FreeBSD as a Xen™ host or guest.