1.\" $NetBSD: xbd.4,v 1.4 2014/03/18 18:20:39 riastradh 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 XBD 4 xen 32.Os 33.Sh NAME 34.Nm xbd 35.Nd Xen frontend paravirtualized block device interface 36.Sh SYNOPSIS 37.Cd "xbd* at xenbus?" 38.Sh DESCRIPTION 39The 40.Nm 41interface forms the frontend part of the paravirtualized drivers 42used by 43.Tn Xen 44guest domains to have a block device interface. 45.Pp 46From a guest point of view, 47.Nm 48is similar to a hard disk, and can be treated in the very same way 49regarding partitioning, file systems creation and usage, and mounting. 50By default, a 51.Nx 52guest domain will assume that 53.Dq xbd0a 54serves as the root file system. 55.Pp 56When the host is 57.Nx , 58the 59.Nm 60interface is backed by a 61.Xr xbdback 4 62interface. 63In the XenStore, 64.Nm xbd 65and 66.Nm xbdback 67are identified by 68.Dq vbd 69(virtual block device) 70entries. 71.Sh DIAGNOSTICS 72.Bl -diag 73.It "xbd%d: using event channel %d" 74Specifies the event channel used by this 75.Nm 76interface. 77.It "xbd%d: %s MB, %d bytes/sect x %u sectors" 78Gives the total size of the 79.Nm 80block device, its sector size and total number of sectors. 81.It "xbd%d: WARNING: cache flush not supported by backend" 82The backend driver associated with this 83.Nm 84device does not support cache flushing operation. 85This can be problematic for file system operations that require 86cache sync to avoid data loss or corruption. 87.El 88.Sh SEE ALSO 89.Xr xbdback 4 , 90.Xr xenbus 4 , 91.Xr dkctl 8 92.Sh HISTORY 93The 94.Nm 95driver first appeared in 96.Nx 3.0 . 97.Sh AUTHORS 98.An -nosplit 99The 100.Nm 101driver was written by 102.An Manuel Bouyer Aq Mt bouyer@NetBSD.org . 103