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Diffstat (limited to 'share/man')
| -rw-r--r-- | share/man/man4/vnd.4 | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/share/man/man4/vnd.4 b/share/man/man4/vnd.4 index 346dde5bc41..8bb26c43bbf 100644 --- a/share/man/man4/vnd.4 +++ b/share/man/man4/vnd.4 @@ -1,3 +1,4 @@ +.\" $OpenBSD: vnd.4,v 1.5 1997/05/14 15:34:05 niklas Exp $ .\" $NetBSD: vnd.4,v 1.1 1995/12/30 18:10:48 thorpej Exp $ .\" .\" Copyright (c) 1995 Jason R. Thorpe. @@ -44,13 +45,25 @@ The .Nm driver provides a disk-like interface to a file. This is useful for a variety of applications, including swap files and building miniroot -or floppy disk images. +or floppy disk images. There are two variants, the traditional +.Nm +that bypasses the buffercache and thus is suitable for swap on files, but +not for building disk-images, and the +.Nm svnd +("safe" +.Nm +) variant that goes +through the buffercache, thereby maintaining cache-coherency after the +block-device is closed which makes it suitable for creating disk images. +The latter is not good for swapping on, though. .Pp This document assumes that you're familiar with how to generate kernels, how to properly configure disks and pseudo-devices in a kernel configuration file. .Pp -In order to compile in support for the vnd, you must add a line similar +In order to compile in support for the +.Nm +, you must add a line similar to the following to your kernel configuration file: .Bd -unfilled -offset indent pseudo-device vnd 4 # vnode disk driver @@ -71,12 +84,15 @@ for more information. The .Nm driver does not work if the file does not reside in a local filesystem. +However the +.Nm svnd +variant does. .Sh FILES -/dev/{,r}vnd* - vnd device special files. +/dev/{,r}{,s}vnd* - vnd device special files. .Pp .Sh HISTORY The vnode disk driver was originally written at the University of -Utah. +Utah. The svnd variant was first seen in OpenBSD 2.1 .Sh SEE ALSO .Xr MAKEDEV 8 , .Xr config 8 , |