.\"	$NetBSD: xenbus.4,v 1.3 2014/03/18 18:20:39 riastradh Exp $
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.Dd January 8, 2011
.Dt XENBUS 4 xen
.Os
.Sh NAME
.Nm xenbus
.Nd Xen bus abstraction for paravirtualized drivers
.Sh SYNOPSIS
.Cd "xenbus* at hypervisor?"
.Sh DESCRIPTION
The
.Nm
interface offers an abstraction layer used for communications
between domains.
.Nm
is mainly used by split paravirtualized drivers, so backend and frontend
devices can exchange configuration information, properties, and
statistics.
.Pp
.Nm
is not used for data transfer (network frames, blocks,
PCI commands, ...). This functionality is implemented by each paravirtualized
driver independently, typically via shared memory pages and an event
channel that serves as a virtual interrupt, for signaling.
.Pp
The
.Nm
abstraction offers guests the possibility to read and write information
directly from and to XenStore, a centralized database accessible to
all domains.
For this reason, it also has an event channel associated to it, so that
domains can post messages to the XenStore facility.
.Sh DIAGNOSTICS
.Bl -diag
.It "xenbus0: using event channel %d"
The event channel associated to the
.Nm
interface, for communication with the XenStore database.
.El
.Sh SEE ALSO
.Xr pciback 4 ,
.Xr xbd 4 ,
.Xr xbdback 4 ,
.Xr xennet 4 ,
.Xr xpci 4 ,
.Xr xvif 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Nx 3.0 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An Manuel Bouyer Aq Mt bouyer@NetBSD.org .