1 .\" Copyright (c) 1993 University of Utah.
2 .\" Copyright (c) 1980, 1989, 1991, 1993
3 .\" The Regents of the University of California. All rights reserved.
5 .\" Poul-Henning Kamp All rights reserved.
7 .\" This code is derived from software contributed to Berkeley by
8 .\" the Systems Programming Group of the University of Utah Computer
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39 .\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93
40 .\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29
49 .Nd configure and enable memory disks
55 .Oo Fl o Oo Cm no Oc Ns Ar option Oc ...
58 .Op Fl S Ar sectorsize
60 .Op Fl x Ar sectors/track
61 .Op Fl y Ar heads/cylinder
65 .Op Fl o Oo Cm no Oc Ns Ar force
77 utility configures and enables
81 Options indicate an action to be performed:
82 .Bl -tag -width indent
85 This will configure and attach a memory disk with the
86 parameters specified and attach it to the system.
88 Detach a memory disk from the system and release all resources.
90 Select the type of the memory disk.
91 .Bl -tag -width "malloc"
93 Storage for this type of memory disk is allocated with
95 This limits the size to the malloc bucket limit in the kernel.
98 option is not set, creating and filling a large
99 malloc-backed memory disk is a very easy way to
102 A file specified with
104 becomes the backing store for this memory disk.
106 Storage for this type of memory disk is allocated from buffer
108 Pages get pushed out to swap when the system is under memory
109 pressure, otherwise they stay in the operating memory.
112 backing is generally preferred instead of using
117 Filename to use for the vnode type memory disk.
122 options are implied if not specified.
124 List configured devices.
127 display details about that particular device.
132 device names of which
134 is used as the backing store.
139 options are specified,
140 display devices which match the two conditions.
143 option is specified, show all details.
147 device names, print only the unit number without the
151 Size of the memory disk.
153 is the number of 512 byte sectors unless suffixed with a
158 denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
163 options are implied if not specified.
164 .It Fl S Ar sectorsize
165 Sectorsize to use for the memory disk, in bytes.
166 .It Fl x Ar sectors/track
167 See the description of the
170 .It Fl y Ar heads/cylinder
179 options can be used to specify a synthetic geometry.
180 This is useful for constructing bootable images for later download to
182 .It Fl o Oo Cm no Oc Ns Ar option
183 Set or reset options.
184 .Bl -tag -width indent
185 .It Oo Cm no Oc Ns Cm async
188 backed devices: avoid
190 for increased performance but
191 at the risk of deadlocking the entire kernel.
192 .It Oo Cm no Oc Ns Cm reserve
193 Allocate and reserve all needed storage from the start, rather than as needed.
194 .It Oo Cm no Oc Ns Cm cluster
195 Enable clustering on this disk.
196 .It Oo Cm no Oc Ns Cm compress
197 Enable/disable compression features to reduce memory usage.
198 .It Oo Cm no Oc Ns Cm force
199 Disable/enable extra sanity checks to prevent the user from doing something
200 that might adversely affect the system.
201 .It Oo Cm no Oc Ns Cm readonly
202 Enable/disable readonly mode.
205 Request a specific unit number for the
207 device instead of automatic allocation.
213 is provided for convenience as an abbreviation of
222 The name of the allocated unit will be printed on stdout, such as
225 .Dl mdconfig -a -t malloc -s 4m
233 .Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4
235 Detach and free all resources used by
240 Create a 128MByte swap backed disk, initialize an
242 file system on it, and mount it on
244 .Bd -literal -offset indent
245 mdconfig -a -t swap -s 128M -u 10
251 Create a 5MB file-backed disk
256 .Bd -literal -offset indent
257 dd if=/dev/zero of=somebackingfile bs=1k count=5k
258 mdconfig -f somebackingfile -u 0
266 device out of an ISO 9660 CD image file
270 are implied), using the first available
272 device, and then mount the new memory disk:
273 .Bd -literal -offset indent
274 mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
277 Create a file-backed device from a hard disk image that begins
278 with 512K of raw header information.
280 is used to skip over the header information, positioning
282 to the start of the filesystem in the image.
283 .Bd -literal -offset indent
284 mdconfig -f diskimage.img -u 1
285 gnop create -o 512K md1
286 mount /dev/md1.nop /mnt
298 utility first appeared in
300 as a cleaner replacement for the
308 utility was written by
309 .An Poul-Henning Kamp
310 .Aq phk@FreeBSD.org .