1.\" $NetBSD: xbdback.4,v 1.2 2011/01/11 10:48:05 wiz Exp $ 2.\" 3.\" Copyright (c) 2011 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jean-Yves Migeon <jym@NetBSD.org>. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd January 8, 2011 31.Dt XBDBACK 4 xen 32.Os 33.Sh NAME 34.Nm xbdback 35.Nd Xen backend paravirtualized block device interface 36.Sh SYNOPSIS 37.Cd "pseudo-device xbdback" 38.Sh DESCRIPTION 39The 40.Nm 41interface forms the backend part of the paravirtualized drivers 42used by 43.Tn Xen 44domains to offer a block device interface, similar to a hard disk. 45.Pp 46For 47.Nx , 48the guest device name specified in the guest configuration file 49does not matter, and can be chosen arbitrarily. 50.Nm 51interfaces are backed either by a physical device directly, 52or an image file mounted through 53.Xr vnd 4 . 54.Pp 55A 56.Nm 57interface will appear as a 58.Xr xbd 4 59block device inside a 60.Nx 61guest domain. 62In the XenStore, 63.Nm xbd 64and 65.Nm xbdback 66are identified by 67.Dq vbd 68(virtual block device) 69entries. 70.Sh DIAGNOSTICS 71.Bl -diag 72.It "xbd backend: attach device %s (size %d) for domain %d" 73Gives the device used as 74.Nm 75interface for the given guest domain, and its size, in bytes. 76.It "xbd backend 0x%x for domain %d using event channel %d, protocol %s" 77Gives the backend identifier, guest domain ID, event channel ID, and 78protocol used for block level communication. 79.It "xbdback %s: can't VOP_OPEN device 0x%x: %d" 80When this message appears in the system message buffer with error 16 81.Po Er EBUSY Pc , 82the device is likely to be already mounted. 83It must be unmounted first, as the system will refuse to open 84it a second time. 85.El 86.Sh SEE ALSO 87.Xr vnd 4 , 88.Xr xbd 4 , 89.Xr xenbus 4 90.Sh HISTORY 91The 92.Nm 93driver first appeared in 94.Nx 4.0 . 95.Sh AUTHORS 96.An -nosplit 97The 98.Nm 99driver was written by 100.An Manuel Bouyer Aq bouyer@NetBSD.org . 101