BHYVE_CONFIG(5) FreeBSD File Formats Manual BHYVE_CONFIG(5)
NAME
bhyve_config - bhyve configuration variables
DESCRIPTION
bhyve(8) uses a hierarchical tree of configuration variables to describe
global and per-device settings. Internal nodes in this tree do not have
a value, only leaf nodes have values. This manual describes the
configuration variables understood by bhyve(8). If additional variables
are defined, bhyve(8) will ignore them and will not emit errors for
unknown variables. However, these additional variables can be referenced
by other variables as described below.
VARIABLE VALUES
Configuration variable values are stored as strings. A configuration
variable value may refer to one or more other configuration values by
name. Instances of the pattern `%(var)' are replaced by the value of the
configuration variable var. To avoid unwanted expansion, `%' characters
can be escaped by a leading `%'. For example, if a configuration
variable disk uses the value /dev/zvol/bhyve/%(name), then the final
value of the disk variable will be set to the path of a ZFS volume whose
name matches the name of the virtual machine on the pool bhyve.
Some configuration variables may be interpreted as a boolean value. For
those variables the following case-insensitive values may be used to
indicate true:
• true
• on
• yes
• 1
The following values may be used to indicate false:
• false
• off
• no
• 0
Some configuration variables may be interperted as an integer. For those
variables, any syntax supported by strtol(3) may be used.
GLOBAL SETTINGS
Architecture Neutral Settings
Name Format Default Description
name string The name of the VM.
cpus integer 1 The total number of virtual
CPUs.
cores integer 1 The number of virtual cores
in each virtual socket.
threads integer 1 The number of virtual CPUs
in each virtual core.
sockets integer 1 The number of virtual
sockets.
memory.guest_in_core bool false Include guest memory in
core file.
memory.size string 256M Guest physical memory size
in bytes. The value must
be formatted as described
in expand_number(3).
memory.wired bool false Wire guest memory.
acpi_tables bool false Generate ACPI tables.
destroy_on_poweroff bool false Destroy the VM on guest-
initiated power-off.
gdb.port integer 0 TCP port number for the
debug server. If this is
set to a non-zero value, a
debug server will listen
for connections on this
port.
gdb.wait bool false If the debug server is
enabled, wait for a
debugger to connect before
starting the guest.
rtc.use_localtime bool true The real time clock uses
the local time of the host.
If this is set to false,
the real time clock uses
UTC.
uuid string The universally unique
identifier (UUID) to use in
the guest's System
Management BIOS System
Information structure. If
an explicit value is not
set, a valid UUID is
generated from the host's
hostname and the VM name.
virtio_msix bool true Use MSI-X interrupts for
PCI VirtIO devices. If set
to false, MSI interrupts
are used instead.
config.dump bool false If this value is set to
true after bhyve(8) has
finished parsing command
line options, then bhyve(8)
will write all of its
configuration variables to
stdout and exit. No VM
will be started.
x86-Specific Settings
Name Format Default Description
x86.mptable bool true Generate an MPTable.
x86.x2apic bool false Configure guest's local
APICs in x2APIC mode.
x86.strictio bool false Exit if a guest accesses an
I/O port that is not
emulated. By default,
writes are ignored and reads
return all bits set.
x86.strictmsr bool true Inject a general protection
fault if a guest accesses a
Model Specific Register
(MSR) that is not emulated.
If this is false, writes are
ignored and reads return
zero.
x86.vmexit_on_hlt bool false Force a VM exit when a guest
CPU executes the HLT
instruction. This allows
idle guest CPUs to yield the
host CPU.
x86.vmexit_on_pause bool false Force a VM exit when a guest
CPU executes the PAUSE
instruction.
DEVICE SETTINGS
Device settings are stored under a device node. The device node's name
is set by the parent bus of the device.
PCI Device Settings
PCI devices are described by a device node named "pcibus.slot.function"
where each of bus, slot, and function are formatted as decimal values
with no padding. All PCI device nodes must contain a configuration
variable named "device" which specifies the device model to use. The
following PCI device models are supported:
hostbridge
Provide a simple PCI-Host bridge device. This is usually
configured at pci0:0:0 and is required by most guest operating
systems.
ahci AHCI storage controller.
e1000 Intel e82545 network interface.
fbuf VGA framebuffer device attached to VNC server.
lpc LPC PCI-ISA bridge with COM1-COM4 16550 serial ports, a boot ROM,
and an optional debug/test device. This device must be
configured on bus 0.
hda High Definition audio controller.
nvme NVM Express (NVMe) controller.
passthru
PCI pass-through device.
uart PCI 16550 serial device.
virtio-9p
VirtIO 9p (VirtFS) interface.
virtio-blk
VirtIO block storage interface.
virtio-console
VirtIO console interface.
virtio-net
VirtIO network interface.
virtio-rnd
VirtIO RNG interface.
virtio-scsi
VirtIO SCSI interface.
xhci Extensible Host Controller Interface (XHCI) USB controller.
USB Device Settings
USB controller devices contain zero or more child USB devices attached to
slots. Each USB device stores its settings in a node named "slot.N"
under the controller's device node. N is the number of the slot to which
the USB device is attached. Note that USB slot numbers begin at 1. All
USB device nodes must contain a configuration variable named "device"
which specifies the device model to use. The following USB device models
are supported:
tablet A USB tablet device which provides precise cursor synchronization
when using VNC.
Block Device Settings
Block devices use the following settings to configure their backing
store. These settings are stored in the configuration node of the
respective device.
Name Format Default Description
path string The path of the file or
disk device to use as the
backing store.
nocache bool false Disable caching on the
backing file by opening
the backing file with
O_DIRECT.
nodelete bool false Disable emulation of guest
trim requests via
DIOCGDELETE requests.
sync bool false Write changes to the
backing file with
synchronous writes.
direct bool false An alias for sync.
ro bool false Disable writes to the
backing file.
sectorsize logical[/physical] Specify the logical and
physical sector size of
the emulated disk. If the
physical size is not
specified, it is equal to
the logical size.
Network Backend Settings
Network devices use the following settings to configure their backend.
The backend is responsible for passing packets between the device model
and a desired destination. Configuring a backend requires setting the
backend variable to one of the following values:
tapN Use the named tap(4) interface as the backend.
vmnetN Use the named vmnet(4) interface as the backend.
netgraph
Use a netgraph(4) socket hook as the backend. This backend uses
the following additional variables:
Name Format Default Description
path string The name of the netgraph(4)
destination node.
peerhook string The name of the destination
hook.
socket string The name of the created
ng_socket(4) node.
hook string vmlink The name of the source hook on
the created ng_socket(4) node.
netmap:interface
Use netmap(4) on a network interface as the backend.
valebridge:port
Use a port on a vale(4) bridge as the backend.
UART Device Settings
Name Format Default Description
path path Backend device for the serial port. Either
the pathname of a character device or
"stdio" to use standard input and output of
the bhyve(8) process.
Host Bridge Settings
Name Format Default Description
vendor integer 0x1275 PCI vendor ID.
devid integer 0x1275 PCI device ID.
AHCI Controller Settings
AHCI controller devices contain zero or more ports each of which provides
a storage device. Each port stores its settings in a node named "port.N"
under the controller's device node. The N values are formatted as
successive decimal values starting with 0. In addition to the block
device settings described above, each port supports the following
settings:
Name Format Default Description
type string The type of storage device to emulate.
Must be set to either "cd" or "hd".
nmrr integer 0 Nominal Media Rotation Rate, also known
as RPM. A value 1 of indicates a device
with no rate such as a Solid State Disk.
ser string generated Serial number of up to twenty
characters. A default serial number is
generated using a hash of the backing
store's pathname.
rev string 001 Revision number of up to eight
characters.
model string Model number of up to forty characters.
Separate default model strings are used
for "cd" and "hd" device types.
e1000 Settings
In addition to the network backend settings, Intel e82545 network
interfaces support the following variables:
Name Format Default Description
mac MAC address generated MAC address. If an explicit address
is not provided, a MAC address is
generated from a hash of the device's
PCI address.
Frame Buffer Settings
Name Format Default Description
wait bool false Wait for a remote connection
before starting the VM.
rfb [IP:]port 127.0.0.1:5900 TCP address to listen on for
remote connections. The IP
address must be given as a
numeric address. IPv6
addresses must be enclosed in
square brackets and support
scoped identifiers as
described in getaddrinfo(3).
A bare port number may be
given in which case the IPv4
localhost address is used.
vga string io VGA configuration. More
details are provided in
bhyve(8).
w integer 1024 Frame buffer width in pixels.
h integer 768 Frame buffer height in pixels.
password string Password to use for VNC
authentication. This type of
authentication is known to be
cryptographically weak and is
not intended for use on
untrusted networks.
High Definition Audio Settings
Name Format Default Description
play path Host playback device, typically /dev/dsp0.
rec path Host recording device, typically /dev/dsp0.
LPC Device Settings
The LPC bridge stores its configuration under a top-level lpc node rather
than under the PCI LPC device's node. The following nodes are available
under lpc:
Name Format Default Description
bootrom path Path to a boot ROM. The contents of
this file are copied into the guest's
memory ending just before the 4GB
physical address. If a boot ROM is
present, a firmware interface device
is also enabled for use by the boot
ROM.
com1 node Settings for the COM1 serial port
device.
com2 node Settings for the COM2 serial port
device.
com3 node Settings for the COM3 serial port
device.
com4 node Settings for the COM4 serial port
device.
pc-testdev bool false Enable the PC debug/test device.
NVMe Controller Settings
Each NVMe controller supports a single storage device. The device can be
backed either by a memory disk described by the ram variable, or a block
device using the the block device settings described above. In addition,
each controller supports the following settings:
Name Format Default Description
maxq integer 16 Maximum number of I/O submission and
completion queue pairs.
qsz integer 2058 Number of elements in each I/O queue.
ioslots integer 8 Maximum number of concurrent I/O
requests.
sectsz integer Sector size. Can be one of 512, 4096, or
8192. Devices backed by a memory disk
use 4096 as the default. Devices backed
by a block device use the block device's
sector size as the default.
ser string Serial number of up to twenty characters.
A default serial number is generated
using a hash of the device's PCI address.
eui64 integer IEEE Extended Unique Identifier. If an
EUI is not provided, a default is
generated using a checksum of the
device's PCI address.
dsm string auto Whether or not to advertise DataSet
Management support. One of "auto",
"enable", or "disable". The "auto"
setting only advertises support if the
backing store supports resource freeing,
for example via TRIM.
ram integer If set, allocate a memory disk as the
backing store. The value of this
variable is the size of the memory disk
in megabytes.
PCI Passthrough Settings
Name Format Default Description
bus integer Host PCI bus address of device to pass
through.
slot integer Host PCI slot address of device to pass
through.
func integer Host PCI function address of device to pass
through.
VirtIO 9p Settings
Each VirtIO 9p device exposes a single filesystem from a host path.
Name Format Default Description
sharename string The share name exposed to the guest.
path path The path of a directory on the host to
export to the guest.
ro bool false If true, the guest filesystem is read-
only.
VirtIO Block Device Settings
In addition to the block device settings described above, each VirtIO
block device supports the following settings:
Name Format Default Description
ser string generated Serial number of up to twenty
characters. A default serial number is
generated using a hash of the backing
store's pathname.
VirtIO Console Device Settings
Each VirtIO Console device contains one or more console ports. Each port
stores its settings in a node named "port.N" under the controller's
device node. The N values are formatted as successive decimal values
starting with 0. Each port supports the following settings:
Name Format Default Description
name string The name of the port exposed to the guest.
path path The path of a UNIX domain socket providing
the host connection for the port.
VirtIO Network Interface Settings
In addition to the network backend settings, VirtIO network interfaces
support the following variables:
Name Format Default Description
mac MAC address generated MAC address. If an explicit address
is not provided, a MAC address is
generated from a hash of the device's
PCI address.
mtu integer 1500 The largest supported MTU advertised
to the guest.
VirtIO SCSI Settings
Name Format Default Description
dev path The path of a CAM target layer (CTL) device
to export: /dev/cam/ctl[pp.vp].
iid integer 0 Initiator ID to use when sending requests
to the CTL port.
SEE ALSO
expand_number(3), getaddrinfo(3), strtol(3), netgraph(4), netmap(4),
ng_socket(4), tap(4), vale(4), vmnet(4), bhyve(8)
FreeBSD 13.1-RELEASE-p6 September 17, 2021 FreeBSD 13.1-RELEASE-p6
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