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26 .Dd September 17, 2021
31 .Nd "bhyve configuration variables"
34 uses a hierarchical tree of configuration variables to describe global and
36 Internal nodes in this tree do not have a value,
37 only leaf nodes have values.
38 This manual describes the configuration variables understood by
40 If additional variables are defined,
42 will ignore them and will not emit errors for unknown variables.
43 However, these additional variables can be referenced by other
44 variables as described below.
46 Configuration variable values are stored as strings.
47 A configuration variable value may refer to one or more other
48 configuration values by name.
49 Instances of the pattern
51 are replaced by the value of the configuration variable
53 To avoid unwanted expansion,
55 characters can be escaped by a leading
58 if a configuration variable
61 .Pa /dev/zvol/bhyve/%(name) ,
62 then the final value of the
64 variable will be set to the path of a ZFS volume whose name matches
65 the name of the virtual machine on the pool
68 Some configuration variables may be interpreted as a boolean value.
69 For those variables the following case-insensitive values may be used to
72 .Bl -bullet -offset indent -compact
83 The following values may be used to indicate false:
85 .Bl -bullet -offset indent -compact
96 Some configuration variables may be interperted as an integer.
98 any syntax supported by
102 .Ss Architecture Neutral Settings
103 .Bl -column "memory.guest_in_core" "integer" "Default"
104 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
105 .It Va name Ta string Ta Ta
107 .It Va cpus Ta integer Ta 1 Ta
108 The total number of virtual CPUs.
109 .It Va cores Ta integer Ta 1 Ta
110 The number of virtual cores in each virtual socket.
111 .It Va threads Ta integer Ta 1 Ta
112 The number of virtual CPUs in each virtual core.
113 .It Va sockets Ta integer Ta 1 Ta
114 The number of virtual sockets.
115 .It Va memory.guest_in_core Ta bool Ta false Ta
116 Include guest memory in core file.
117 .It Va memory.size Ta string Ta 256M Ta
118 Guest physical memory size in bytes.
119 The value must be formatted as described in
120 .Xr expand_number 3 .
121 .It Va memory.wired Ta bool Ta false Ta
123 .It Va acpi_tables Ta bool Ta false Ta
124 Generate ACPI tables.
125 .It Va destroy_on_poweroff Ta bool Ta false Ta
126 Destroy the VM on guest-initiated power-off.
127 .It Va gdb.port Ta integer Ta 0 Ta
128 TCP port number for the debug server.
129 If this is set to a non-zero value, a debug server
130 will listen for connections on this port.
131 .It Va gdb.wait Ta bool Ta false Ta
132 If the debug server is enabled, wait for a debugger to connect
133 before starting the guest.
134 .It Va rtc.use_localtime Ta bool Ta true Ta
135 The real time clock uses the local time of the host.
136 If this is set to false, the real time clock uses UTC.
137 .It Va uuid Ta string Ta Ta
138 The universally unique identifier (UUID) to use in the guest's
139 System Management BIOS System Information structure.
140 If an explicit value is not set, a valid UUID is generated from
141 the host's hostname and the VM name.
142 .It Va virtio_msix Ta bool Ta true Ta
143 Use MSI-X interrupts for PCI VirtIO devices.
144 If set to false, MSI interrupts are used instead.
145 .It Va config.dump Ta bool Ta false Ta
146 If this value is set to true after
148 has finished parsing command line options,
151 will write all of its configuration variables to stdout and exit.
152 No VM will be started.
154 .Ss x86-Specific Settings
155 .Bl -column "x86.vmexit_on_pause" "integer" "Default"
156 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
157 .It Va x86.mptable Ta bool Ta true Ta
159 .It Va x86.x2apic Ta bool Ta false Ta
160 Configure guest's local APICs in x2APIC mode.
161 .It Va x86.strictio Ta bool Ta false Ta
162 Exit if a guest accesses an I/O port that is not emulated.
163 By default, writes are ignored and reads return all bits set.
164 .It Va x86.strictmsr Ta bool Ta true Ta
165 Inject a general protection fault if a guest accesses a Model Specific
166 Register (MSR) that is not emulated.
167 If this is false, writes are ignored and reads return zero.
168 .It Va x86.vmexit_on_hlt Ta bool Ta false Ta
169 Force a VM exit when a guest CPU executes the
172 This allows idle guest CPUs to yield the host CPU.
173 .It Va x86.vmexit_on_pause Ta bool Ta false Ta
174 Force a VM exit when a guest CPU executes the
179 Device settings are stored under a device node.
180 The device node's name is set by the parent bus of the device.
181 .Ss PCI Device Settings
182 PCI devices are described by a device node named
183 .Dq pci Ns Ar bus . Ns Ar slot . Ns Ar function
189 are formatted as decimal values with no padding.
190 All PCI device nodes must contain a configuration variable named
192 which specifies the device model to use.
193 The following PCI device models are supported:
196 Provide a simple PCI-Host bridge device.
197 This is usually configured at pci0:0:0 and is required by most guest
200 AHCI storage controller.
202 Intel e82545 network interface.
204 VGA framebuffer device attached to VNC server.
206 LPC PCI-ISA bridge with COM1-COM4 16550 serial ports,
208 and an optional debug/test device.
209 This device must be configured on bus 0.
211 High Definition audio controller.
213 NVM Express (NVMe) controller.
215 PCI pass-through device.
217 PCI 16550 serial device.
219 VirtIO 9p (VirtFS) interface.
221 VirtIO block storage interface.
222 .It Li virtio-console
223 VirtIO console interface.
225 VirtIO network interface.
227 VirtIO RNG interface.
229 VirtIO SCSI interface.
231 Extensible Host Controller Interface (XHCI) USB controller.
233 .Ss USB Device Settings
234 USB controller devices contain zero or more child USB devices
236 Each USB device stores its settings in a node named
238 under the controller's device node.
240 is the number of the slot to which the USB device is attached.
241 Note that USB slot numbers begin at 1.
242 All USB device nodes must contain a configuration variable named
244 which specifies the device model to use.
245 The following USB device models are supported:
248 A USB tablet device which provides precise cursor synchronization
251 .Ss Block Device Settings
252 Block devices use the following settings to configure their backing store.
253 These settings are stored in the configuration node of the respective device.
254 .Bl -column "sectorsize" "logical[/physical]" "Default"
255 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
256 .It path Ta string Ta Ta
257 The path of the file or disk device to use as the backing store.
258 .It nocache Ta bool Ta false Ta
259 Disable caching on the backing file by opening the backing file with
261 .It nodelete Ta bool Ta false Ta
262 Disable emulation of guest trim requests via
265 .It sync Ta bool Ta false Ta
266 Write changes to the backing file with synchronous writes.
267 .It direct Ta bool Ta false Ta
270 .It ro Ta bool Ta false Ta
271 Disable writes to the backing file.
272 .It sectorsize Ta Va logical Ns Op / Ns Va physical Ta Ta
273 Specify the logical and physical sector size of the emulated disk.
274 If the physical size is not specified,
275 it is equal to the logical size.
277 .Ss Network Backend Settings
278 Network devices use the following settings to configure their backend.
279 The backend is responsible for passing packets between the device model
280 and a desired destination.
281 Configuring a backend requires setting the
283 variable to one of the following values:
288 interface as the backend.
292 interface as the backend.
296 socket hook as the backend.
297 This backend uses the following additional variables:
298 .Bl -column "peerhook" "Format" "Default"
299 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
300 .It Va path Ta string Ta Ta
304 .It Va peerhook Ta string Ta Ta
305 The name of the destination hook.
306 .It Va socket Ta string Ta Ta
307 The name of the created
310 .It Va hook Ta string Ta vmlink Ta
311 The name of the source hook on the created
315 .It netmap: Ns Va interface
318 on a network interface as the backend.
319 .It vale Ns Va bridge : Ns Va port
322 bridge as the backend.
324 .Ss UART Device Settings
325 .Bl -column "Name" "Format" "Default"
326 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
327 .It Va path Ta path Ta Ta
328 Backend device for the serial port.
329 Either the pathname of a character device or
331 to use standard input and output of the
335 .Ss Host Bridge Settings
336 .Bl -column "vendor" "integer" "Default"
337 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
338 .It Va vendor Ta integer Ta 0x1275 Ta
340 .It Va devid Ta integer Ta 0x1275 Ta
343 .Ss AHCI Controller Settings
344 AHCI controller devices contain zero or more ports each of which
345 provides a storage device.
346 Each port stores its settings in a node named
348 under the controller's device node.
351 values are formatted as successive decimal values starting with 0.
352 In addition to the block device settings described above, each
353 port supports the following settings:
354 .Bl -column "model" "integer" "generated"
355 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
356 .It Va type Ta string Ta Ta
357 The type of storage device to emulate.
358 Must be set to either
362 .It Va nmrr Ta integer Ta 0 Ta
363 Nominal Media Rotation Rate, also known as RPM.
364 A value 1 of indicates a device with no rate such as a Solid State Disk.
365 .It Va ser Ta string Ta generated Ta
366 Serial number of up to twenty characters.
367 A default serial number is generated using a hash of the backing
369 .It Va rev Ta string Ta 001 Ta
370 Revision number of up to eight characters.
371 .It Va model Ta string Ta Ta
372 Model number of up to forty characters.
373 Separate default model strings are used for
380 In addition to the network backend settings,
381 Intel e82545 network interfaces support the following variables:
382 .Bl -column "Name" "MAC address" "generated"
383 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
384 .It Va mac Ta MAC address Ta generated Ta
386 If an explicit address is not provided,
387 a MAC address is generated from a hash of the device's PCI address.
389 .Ss Frame Buffer Settings
390 .Bl -column "password" "[IP:]port" "127.0.0.1:5900"
391 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
392 .It Va wait Ta bool Ta false Ta
393 Wait for a remote connection before starting the VM.
394 .It Va rfb Ta Oo Ar IP Ns : Oc Ns Ar port Ta 127.0.0.1:5900 Ta
395 TCP address to listen on for remote connections.
396 The IP address must be given as a numeric address.
397 IPv6 addresses must be enclosed in square brackets and
398 support scoped identifiers as described in
400 A bare port number may be given in which case the IPv4
401 localhost address is used.
402 .It Va vga Ta string Ta io Ta
404 More details are provided in
406 .It Va w Ta integer Ta 1024 Ta
407 Frame buffer width in pixels.
408 .It Va h Ta integer Ta 768 Ta
409 Frame buffer height in pixels.
410 .It Va password Ta string Ta Ta
411 Password to use for VNC authentication.
412 This type of authentication is known to be cryptographically weak and is not
413 intended for use on untrusted networks.
415 .Ss High Definition Audio Settings
416 .Bl -column "Name" "Format" "Default"
417 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
418 .It Va play Ta path Ta Ta
419 Host playback device,
422 .It Va rec Ta path Ta Ta
423 Host recording device,
427 .Ss LPC Device Settings
428 The LPC bridge stores its configuration under a top-level
430 node rather than under the PCI LPC device's node.
431 The following nodes are available under
433 .Bl -column "pc-testdev" "Format" "Default"
434 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
435 .It Va bootrom Ta path Ta Ta
437 The contents of this file are copied into the guest's
438 memory ending just before the 4GB physical address.
439 If a boot ROM is present, a firmware interface device is
440 also enabled for use by the boot ROM.
441 .It Va com1 Ta node Ta Ta
442 Settings for the COM1 serial port device.
443 .It Va com2 Ta node Ta Ta
444 Settings for the COM2 serial port device.
445 .It Va com3 Ta node Ta Ta
446 Settings for the COM3 serial port device.
447 .It Va com4 Ta node Ta Ta
448 Settings for the COM4 serial port device.
449 .It Va pc-testdev Ta bool Ta false Ta
450 Enable the PC debug/test device.
452 .Ss NVMe Controller Settings
453 Each NVMe controller supports a single storage device.
454 The device can be backed either by a memory disk described by the
456 variable, or a block device using the the block device settings described above.
457 In addition, each controller supports the following settings:
458 .Bl -column "ioslots" "Format" "Default"
459 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
460 .It Va maxq Ta integer Ta 16 Ta
461 Maximum number of I/O submission and completion queue pairs.
462 .It Va qsz Ta integer Ta 2058 Ta
463 Number of elements in each I/O queue.
464 .It Va ioslots Ta integer Ta 8 Ta
465 Maximum number of concurrent I/O requests.
466 .It Va sectsz Ta integer Ta Ta
468 Can be one of 512, 4096, or 8192.
469 Devices backed by a memory disk use 4096 as the default.
470 Devices backed by a block device use the block device's sector size
472 .It Va ser Ta string Ta Ta
473 Serial number of up to twenty characters.
474 A default serial number is generated using a hash of the device's PCI address.
475 .It Va eui64 Ta integer Ta Ta
476 IEEE Extended Unique Identifier.
477 If an EUI is not provided, a default is generated using a checksum of the
478 device's PCI address.
479 .It Va dsm Ta string Ta auto Ta
480 Whether or not to advertise DataSet Management support.
488 setting only advertises support if the backing store supports
489 resource freeing, for example via TRIM.
490 .It Va ram Ta integer Ta Ta
491 If set, allocate a memory disk as the backing store.
492 The value of this variable is the size of the memory disk in megabytes.
494 .Ss PCI Passthrough Settings
495 .Bl -column "Name" "integer" "Default"
496 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
497 .It Va bus Ta integer Ta Ta
498 Host PCI bus address of device to pass through.
499 .It Va slot Ta integer Ta Ta
500 Host PCI slot address of device to pass through.
501 .It Va func Ta integer Ta Ta
502 Host PCI function address of device to pass through.
504 .Ss VirtIO 9p Settings
505 Each VirtIO 9p device exposes a single filesystem from a host path.
506 .Bl -column "sharename" "Format" "Default"
507 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
508 .It Va sharename Ta string Ta Ta
509 The share name exposed to the guest.
510 .It Va path Ta path Ta Ta
511 The path of a directory on the host to export to the guest.
512 .It Va ro Ta bool Ta false Ta
513 If true, the guest filesystem is read-only.
515 .Ss VirtIO Block Device Settings
516 In addition to the block device settings described above, each
517 VirtIO block device supports the following settings:
518 .Bl -column "model" "integer" "generated"
519 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
520 .It Va ser Ta string Ta generated Ta
521 Serial number of up to twenty characters.
522 A default serial number is generated using a hash of the backing
525 .Ss VirtIO Console Device Settings
526 Each VirtIO Console device contains one or more console ports.
527 Each port stores its settings in a node named
529 under the controller's device node.
532 values are formatted as successive decimal values starting with 0.
533 Each port supports the following settings:
534 .Bl -column "Name" "Format" "Default"
535 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
536 .It Va name Ta string Ta Ta
537 The name of the port exposed to the guest.
538 .It Va path Ta path Ta Ta
539 The path of a UNIX domain socket providing the host connection for the port.
541 .Ss VirtIO Network Interface Settings
542 In addition to the network backend settings,
543 VirtIO network interfaces support the following variables:
544 .Bl -column "Name" "MAC address" "generated"
545 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
546 .It Va mac Ta MAC address Ta generated Ta
548 If an explicit address is not provided,
549 a MAC address is generated from a hash of the device's PCI address.
550 .It Va mtu Ta integer Ta 1500 Ta
551 The largest supported MTU advertised to the guest.
553 .Ss VirtIO SCSI Settings
554 .Bl -column "Name" "integer" "Default"
555 .It Sy Name Ta Sy Format Ta Sy Default Ta Sy Description
556 .It Va dev Ta path Ta Ta
557 The path of a CAM target layer (CTL) device to export:
558 .Pa /dev/cam/ctl Ns Oo Ar pp . Ns Ar vp Oc .
559 .It Va iid Ta integer Ta 0 Ta
560 Initiator ID to use when sending requests to the CTL port.
563 .Xr expand_number 3 ,