1 .\" $NetBSD: vnd.4,v 1.1 1995/12/30 18:10:48 thorpej Exp $
3 .\" Copyright (c) 1995 Jason R. Thorpe.
4 .\" All rights reserved.
6 .\" Redistribution and use in source and binary forms, with or without
7 .\" modification, are permitted provided that the following conditions
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
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13 .\" documentation and/or other materials provided with the distribution.
14 .\" 3. All advertising materials mentioning features or use of this software
15 .\" must display the following acknowledgement:
16 .\" This product includes software developed for the NetBSD Project
17 .\" by Jason R. Thorpe.
18 .\" 4. Neither the name of the author nor the names of its contributors
19 .\" may be used to endorse or promote products derived from this software
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34 .\" $FreeBSD: src/share/man/man4/vn.4,v 1.6.2.4 2002/04/15 05:48:55 asmodai Exp $
35 .\" $DragonFly: src/share/man/man4/vn.4,v 1.6 2007/06/14 21:16:13 swildner Exp $
44 .Cd "pseudo-device vn"
48 driver uses swap or a file as backing store to abstract-out a character and
49 block device which may then be used like a disk. The
51 driver supports both labeled and unlabeled pseudo-disks and is useful for
52 a variety of applications, including swap files and building mini-root,
53 floppy, or CD-ROM disk images.
55 may also be used to create temporary swap-backed filesystems, such as /tmp,
56 in a somewhat less memory-hungry manner than MFS.
58 This document assumes that you're familiar with how to generate kernels,
59 how to properly configure disks and pseudo-devices in a kernel
62 In order to compile in support for the
64 you must add a line similar
65 to the following to your kernel configuration file:
66 .Bd -unfilled -offset indent
67 pseudo-device vn #Vnode driver
71 may also exist as a kernel module to be automatically loaded into the
72 system when you run the
74 command for the first time.
76 There is a run-time utility that is used for configuring
82 /dev/{,r}vn* - vn device special files.
91 The vnode disk driver was originally written at the University of
92 Utah and was substantially modified by
99 driver does not work if the file does not reside in a local filesystem.