FreeBSD manual
download PDF document: vmm.4.pdf
VMM(4) FreeBSD Kernel Interfaces Manual VMM(4)
NAME
vmm.ko - bhyve virtual machine monitor
SYNOPSIS
To load the driver as a module at boot, add this line to loader.conf(5):
vmm_load="YES"
The module can also be loaded manually with kldload(8):
kldload vmm
DESCRIPTION
vmm.ko provides the kernel portion of the bhyve(4) hypervisor.
An Intel CPU with VT-x/EPT or AMD CPU with SVM support is required.
PCI device passthrough to a virtual machine requires hardware with VT-d
support.
PCI PASSTHROUGH
When the hardware supports VT-d, and vmm.ko has been loaded at boot time,
PCI devices can be reserved for use by the hypervisor. Entries
consisting of the PCI bus/slot/function are added to the pptdevs
loader.conf(5) variable. Additional entries are separated by spaces.
Host PCI devices that match an entry will be assigned to the hypervisor
and will not be probed by FreeBSD device drivers. See the EXAMPLES
section below for sample usage.
Note that vmm must be given first the right of refusal to all pci(4)
devices it may need to claim. As a result, the vmm kernel module almost
certainly needs to be loaded from loader.conf(5) rather than by adding it
to kld_list in rc.conf(5).
A large number of PCI device entries may require a string longer than the
128-character limit of loader.conf(5) variables. The pptdevs2 and
pptdevs3 variables can be used for additional entries.
LOADER TUNABLES
Tunables can be set at the loader(8) prompt before booting the kernel or
stored in loader.conf(5).
hw.vmm.maxcpu
Maximum number of virtual CPUs. The default is the number of
physical CPUs in the system.
EXAMPLES
Reserve three PCI devices for use by the hypervisor: bus 10 slot 0
function 0, bus 6 slot 5 function 0, and bus 6 slot 5 function 1.
pptdevs="10/0/0 6/5/0 6/5/1"
It is possible to detach ppt from a PCI device without rebooting the host
machine and then attach a host driver, using the devctl(8) utility.
Suppose ppt is currently attached to pci0:0:1:0 and we want the host's
xhci(4) driver to be attached instead:
bhyve(4), loader.conf(5), bhyve(8), bhyveload(8), devctl(8), kldload(8)
HISTORY
vmm.ko first appeared in FreeBSD 10.0.
AUTHORS
Neel Natu <neel@freebsd.org>
Peter Grehan <grehan@freebsd.org>
FreeBSD 14.2-RELEASE September 27, 2024 FreeBSD 14.2-RELEASE