1.\" $FreeBSD: head/share/man/man4/hv_vmbus.4 276259 2014-12-26 22:30:18Z bapt $ 2.\" 3.\" Copyright (c) 2012 Microsoft Corp. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.Dd February 24, 2017 28.Dt VMBUS 4 29.Os 30.Sh NAME 31.Nm vmbus 32.Nd Hyper-V Virtual Machine Bus (VMBus) Driver 33.Sh SYNOPSIS 34.Cd "device vmbus" 35.Pp 36Alternatively, to load the driver as a 37module at boot time, place the following line in 38.Xr loader.conf 5 : 39.Bd -literal -offset indent 40vmbus_load="YES" 41.Ed 42.Sh DESCRIPTION 43The 44.Nm 45provides a high performance communication interface between 46guest and root partitions in Hyper-V. 47Hyper-V is a hypervisor-based virtualization technology from Microsoft. 48Hyper-V supports isolation in terms of a partition. 49A partition is a 50logical unit of isolation, supported by the hypervisor, in which 51operating systems execute. 52.Pp 53The Microsoft hypervisor must have at least one parent, or root, 54partition, running Windows Server operating system. 55The virtualization stack runs in the parent partition and has 56direct access to the hardware devices. 57The root partition then creates the child partitions which host 58the guest operating systems. 59.Pp 60Child partitions do not have direct access to other hardware resources 61and are presented 62a virtual view of the resources, as virtual devices (VDevs). 63Requests to the virtual devices are 64redirected either via the VMBus or the hypervisor to the devices in 65the parent partition, which handles the requests. 66.Pp 67The VMBus is a logical inter-partition communication channel. 68The parent partition hosts Virtualization Service Providers (VSPs) 69which communicate over the VMBus to handle device access requests from 70child partitions. 71Child partitions host Virtualization Service 72Consumers (VSCs) which redirect device requests to VSPs in the parent 73partition via the VMBus. 74The Hyper-V VMBus driver defines and implements 75the interface that facilitate high performance bi-directional communication 76between the VSCs and VSPs. 77All VSCs utilize the VMBus driver. 78.\".Sh SEE ALSO 79.\".Xr hv_ata_pci_disengage 4 , 80.\".Xr hv_netvsc 4 , 81.\".Xr hv_storvsc 4 , 82.\".Xr hv_utils 4 83.Sh HISTORY 84Support for 85.Nm 86first appeared in 87.Fx 10.0 88and was subsequently brought into 89.Dx 4.5 . 90The driver was developed through a joint effort between Citrix Incorporated, 91Microsoft Corporation, and Network Appliance Incorporated. 92.Sh AUTHORS 93.An -nosplit 94.Fx 95support for 96.Nm 97was first added by 98.An Microsoft BSD Integration Services Team Aq Mt bsdic@microsoft.com . 99