xref: /dflybsd-src/share/man/man4/vmbus.4 (revision f696b24fe2fb54047df0bb9503ec0469b7068047)

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.Dd February 24, 2017
.Dt VMBUS 4
.Os
.Sh NAME
.Nm vmbus
.Nd Hyper-V Virtual Machine Bus (VMBus) Driver
.Sh SYNOPSIS
.Cd "device vmbus"
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
vmbus_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
provides a high performance communication interface between
guest and root partitions in Hyper-V.
Hyper-V is a hypervisor-based virtualization technology from Microsoft.
Hyper-V supports isolation in terms of a partition.
A partition is a
logical unit of isolation, supported by the hypervisor, in which
operating systems execute.
.Pp
The Microsoft hypervisor must have at least one parent, or root,
partition, running Windows Server operating system.
The virtualization stack runs in the parent partition and has
direct access to the hardware devices.
The root partition then creates the child partitions which host
the guest operating systems.
.Pp
Child partitions do not have direct access to other hardware resources
and are presented
a virtual view of the resources, as virtual devices (VDevs).
Requests to the virtual devices are
redirected either via the VMBus or the hypervisor to the devices in
the parent partition, which handles the requests.
.Pp
The VMBus is a logical inter-partition communication channel.
The parent partition hosts Virtualization Service Providers (VSPs)
which communicate over the VMBus to handle device access requests from
child partitions.
Child partitions host Virtualization Service
Consumers (VSCs) which redirect device requests to VSPs in the parent
partition via the VMBus.
The Hyper-V VMBus driver defines and implements
the interface that facilitate high performance bi-directional communication
between the VSCs and VSPs.
All VSCs utilize the VMBus driver.
.\".Sh SEE ALSO
.\".Xr hv_ata_pci_disengage 4 ,
.\".Xr hv_netvsc 4 ,
.\".Xr hv_storvsc 4 ,
.\".Xr hv_utils 4
.Sh HISTORY
Support for
.Nm
first appeared in
.Fx 10.0
and was subsequently brought into
.Dx 4.5 .
The driver was developed through a joint effort between Citrix Incorporated,
Microsoft Corporation, and Network Appliance Incorporated.
.Sh AUTHORS
.An -nosplit
.Fx
support for
.Nm
was first added by
.An Microsoft BSD Integration Services Team Aq Mt bsdic@microsoft.com .