.\"	$NetBSD: viomb.4,v 1.2 2011/11/26 22:36:14 wiz Exp $
.\"	$OpenBSD: viomb.4,v 1.2 2013/01/16 00:30:48 brad Exp $
.\" Copyright (c) 2012 Dinar Talypov <dinar@i-nk.ru>
.\" Copyright (C) 2011 Minoura Makoto.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer in the
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.Dd $Mdocdate: January 16 2013 $
.Dt VIOMB 4
.Os
.Sh NAME
.Nm viomb
.Nd VirtIO memory ballooning driver
.Sh SYNOPSIS
.Cd "viomb*  at virtio?"
.Sh DESCRIPTION
The
.Nm
driver supports the virtio-compliant memory ballooning device.
.Pp
Memory ballooning works as follows:
.Pp
.Bl -enum -compact
.It
The host operator requests a guest to return some amount of memory to the host
(via, for example, the QEMU monitor balloon command).
.It
The hypervisor sends the request via the VirtIO memory ballooning device.
.It
The guest
.Nm
driver requests allocation of that amount of physical memory from the
.Ox
memory management system.
.It
The
.Nm
device tells the hypervisor the guest physical memory address of the
allocated memory via the VirtIO memory ballooning device.
.El
.Sh SEE ALSO
.Xr intro 4 ,
.Xr virtio 4
.Rs
.%A Rusty Russell, IBM Corporation
.%T Virtio PCI Card Specification
.%U http://ozlabs.org/~rusty/virtio-spec/
.Re
.Sh HISTORY
The
.Nm
device driver first appeared in
.Ox 5.3 .