BHYVE(8) FreeBSD System Manager's Manual BHYVE(8)


bhyverun a guest operating system inside a virtual machine


bhyve [ -abehwxACHPWY][ -c numcpus][ -g gdbport][ -l lpcdev[ , conf]][ -m size[ K|k|M|m|G|g|T|t]][ -p vcpu:hostcpu][ -s slot,emulation[ , conf]][ -U uuid] vmname


bhyve is a hypervisor that runs guest operating systems inside a virtual machine.

Parameters such as the number of virtual CPUs, amount of guest memory, and I/O connectivity can be specified with command-line parameters.

The guest operating system must be loaded with bhyveload(4) or a similar boot loader before running bhyve.

bhyve runs until the guest operating system reboots or an unhandled hypervisor exit is detected.


The guest's local APIC is configured in xAPIC mode. The xAPIC mode is the default setting so this option is redundant. It will be deprecated in a future version.
Generate ACPI tables. Required for FreeBSD/amd64 guests.
Enable a low-level console device supported by FreeBSD kernels compiled with device bvmconsole. This option will be deprecated in a future version.
-c numcpus
Number of guest virtual CPUs. The default is 1 and the maximum is 16.
Include guest memory in core file.
Force bhyve to exit when a guest issues an access to an I/O port that is not emulated. This is intended for debug purposes.
-g gdbport
For FreeBSD kernels compiled with device bvmdebug, allow a remote kernel kgdb to be relayed to the guest kernel gdb stub via a local IPv4 address and this port. This option will be deprecated in a future version.
Print help message and exit.
Yield the virtual CPU thread when a HLT instruction is detected. If this option is not specified, virtual CPUs will use 100% of a host CPU.
-l lpcdev[ , conf]
Allow devices behind the LPC PCI-ISA bridge to be configured. The only supported devices are the TTY-class devices, com1 and com2.
-m size[ K|k|M|m|G|g|T|t]
Guest physical memory size in bytes. This must be the same size that was given to bhyveload(8).

The size argument may be suffixed with one of K, M, G or T (either upper or lower case) to indicate a multiple of kilobytes, megabytes, gigabytes, or terabytes. If no suffix is given, the value is assumed to be in megabytes.

-p vcpu:hostcpu
Pin guest's virtual CPU vcpu to hostcpu.
Force the guest virtual CPU to exit when a PAUSE instruction is detected.
-s slot,emulation[ , conf]
Configure a virtual PCI slot and function.

bhyve provides PCI bus emulation and virtual devices that can be attached to slots on the bus. There are 32 available slots, with the option of providing up to 8 functions per slot.

pcislot[:function] bus:pcislot:function

The pcislot value is 0 to 31. The optional function value is 0 to 7. The optional bus value is 0 to 255. If not specified, the function value defaults to 0. If not specified, the bus value defaults to 0.

hostbridge | amd_hostbridge

Provide a simple host bridge. This is usually configured at slot 0, and is required by most guest operating systems. The amd_hostbridge emulation is identical but uses a PCI vendor ID of AMD.

PCI pass-through device.
Virtio network interface.
Virtio block storage interface.
Virtio RNG interface.
AHCI controller attached to an ATAPI CD/DVD.
AHCI controller attached to a SATA hard-drive.
PCI 16550 serial device.
LPC PCI-ISA bridge with COM1 and COM2 16550 serial ports. The LPC bridge emulation can only be configured on bus 0.
[ conf]
This optional parameter describes the backend for device emulations. If conf is not specified, the device emulation has no backend and can be considered unconnected.

Network devices:

tapN[ , mac=xx:xx:xx:xx:xx:xx]
vmnetN[ , mac=xx:xx:xx:xx:xx:xx]

If mac is not specified, the MAC address is derived from a fixed OUI and the remaining bytes from an MD5 hash of the slot and function numbers and the device name.

The MAC address is an ASCII string in ethers(5) format.

Block storage devices:

/filename[ , nocache][ , direct][ , ro]
/dev/xxx[ , nocache][ , direct][ , ro]
Open the file with O_DIRECT.
Open the file using O_SYNC.
Force the file to be opened read-only.

The nocache, direct, and ro options are not available for virtio block devices.

TTY devices:

Connect the serial port to the standard input and output of the bhyve process.
Use the host TTY device for serial port I/O.

Pass-through devices:

slot/ bus/ function
Connect to a PCI device on the host at the selector described by slot, bus, and function numbers.

The host device must have been reserved at boot-time using the pptdev loader variable as described in vmm(4).

-U uuid
Set the universally unique identifier (UUID) in the guest's System Management BIOS System Information structure. By default a UUID is generated from the host's hostname and vmname.
Ignore accesses to unimplemented Model Specific Registers (MSRs). This is intended for debug purposes.
Force virtio PCI device emulations to use MSI interrupts instead of MSI-X interrupts.
The guest's local APIC is configured in x2APIC mode.
Disable MPtable generation.
Alphanumeric name of the guest. This should be the same as that created by bhyveload(8).


The guest operating system must have been loaded with bhyveload(4) or a similar boot loader before bhyve(4) can be run.

To run a virtual machine with 1GB of memory, two virtual CPUs, a virtio block device backed by the /my/image filesystem image, and a serial port for the console:

bhyve -c 2 -s 0,hostbridge -s 1,lpc -s 2,virtio-blk,/my/image \ 
  -l com1,stdio -A -H -P -m 1G vm1

Run a 24GB single-CPU virtual machine with three network ports, one of which has a MAC address specified:

bhyve -s 0,hostbridge -s 1,lpc -s 2:0,virtio-net,tap0 \ 
  -s 2:1,virtio-net,tap1 \ 
  -s 2:2,virtio-net,tap2,mac=00:be:fa:76:45:00 \ 
  -s 3,virtio-blk,/my/image -l com1,stdio \ 
  -A -H -P -m 24G bigvm

Run an 8GB quad-CPU virtual machine with 8 AHCI SATA disks, an AHCI ATAPI CD-ROM, a single virtio network port, an AMD hostbridge, and the console port connected to an nmdm(4) null-model device.

bhyve -c 4 \  -s 0,amd_hostbridge -s 1,lpc \ 
  -s 1:0,ahci-hd,/images/disk.1 \ 
  -s 1:1,ahci-hd,/images/disk.2 \ 
  -s 1:2,ahci-hd,/images/disk.3 \ 
  -s 1:3,ahci-hd,/images/disk.4 \ 
  -s 1:4,ahci-hd,/images/disk.5 \ 
  -s 1:5,ahci-hd,/images/disk.6 \ 
  -s 1:6,ahci-hd,/images/disk.7 \ 
  -s 1:7,ahci-hd,/images/disk.8 \ 
  -s 2,ahci-cd,/images.install.iso \ 
  -s 3,virtio-net,tap0 \ 
  -l com1,/dev/nmdm0A \ 
  -A -H -P -m 8G


bhyve first appeared in FreeBSD 10.0.


Neel Natu <neel@freebsd.org> Peter Grehan <grehan@freebsd.org>
September 17, 2014 FreeBSD