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
70 .Op Fl o Oo Cm no Oc Ns Ar force
82 utility configures and enables
86 Options indicate an action to be performed:
87 .Bl -tag -width indent
90 This will configure and attach a memory disk with the
91 parameters specified and attach it to the system.
94 option is not provided, the newly created device name will be printed on stdout.
96 Detach a memory disk from the system and release all resources.
100 Select the type of the memory disk.
101 .Bl -tag -width "malloc"
103 Storage for this type of memory disk is allocated with
105 This limits the size to the malloc bucket limit in the kernel.
108 option is not set, creating and filling a large
109 malloc-backed memory disk is a very easy way to
112 A file specified with
114 becomes the backing store for this memory disk.
116 Storage for this type of memory disk is allocated from buffer
118 Pages get pushed out to swap when the system is under memory
119 pressure, otherwise they stay in the operating memory.
122 backing is generally preferred instead of using
127 Filename to use for the vnode type memory disk.
132 options are implied if not specified.
134 List configured devices.
137 display details about that particular device.
142 device names of which
144 is used as the backing store.
149 options are specified,
150 display devices which match the two conditions.
153 option is specified, show all details.
157 device names, print only the unit number without the
161 Size of the memory disk.
163 is the number of 512 byte sectors unless suffixed with a
168 denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
173 options are implied if not specified.
174 .It Fl S Ar sectorsize
175 Sectorsize to use for the memory disk, in bytes.
176 .It Fl x Ar sectors/track
177 See the description of the
180 .It Fl y Ar heads/cylinder
189 options can be used to specify a synthetic geometry.
190 This is useful for constructing bootable images for later download to
192 .It Fl o Oo Cm no Oc Ns Ar option
193 Set or reset options.
194 .Bl -tag -width indent
195 .It Oo Cm no Oc Ns Cm async
198 backed devices: avoid
200 for increased performance but
201 at the risk of deadlocking the entire kernel.
202 .It Oo Cm no Oc Ns Cm reserve
203 Allocate and reserve all needed storage from the start, rather than as needed.
204 .It Oo Cm no Oc Ns Cm cluster
205 Enable clustering on this disk.
206 .It Oo Cm no Oc Ns Cm compress
207 Enable/disable compression features to reduce memory usage.
208 .It Oo Cm no Oc Ns Cm force
209 Disable/enable extra sanity checks to prevent the user from doing something
210 that might adversely affect the system.
211 .It Oo Cm no Oc Ns Cm readonly
212 Enable/disable readonly mode.
215 Request a specific unit number or device name for the
217 device instead of automatic allocation.
218 If a device name is specified, it must be start with
220 followed by the unit number.
226 is provided for convenience as an abbreviation of
235 The name of the allocated unit will be printed on stdout, such as
238 .Dl mdconfig -a -t malloc -s 4m
246 .Dl mdconfig -a -t vnode -f /tmp/boot.flp -u md4
248 Detach and free all resources used by
251 .Dl mdconfig -d -u md4
253 Create a 128MByte swap backed disk, initialize an
255 file system on it, and mount it on
257 .Bd -literal -offset indent
258 mdconfig -a -t swap -s 128M -u md10
264 Create a 5MB file-backed disk
270 .Bd -literal -offset indent
271 dd if=/dev/zero of=somebackingfile bs=1k count=5k
272 mdconfig -f somebackingfile -u md0
280 device out of an ISO 9660 CD image file
285 .Pc , using the first available
287 device, and then mount the new memory disk:
288 .Bd -literal -offset indent
289 mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
292 Create a file-backed device from a hard disk image that begins
293 with 512K of raw header information.
295 is used to skip over the header information, positioning
297 to the start of the filesystem in the image.
298 .Bd -literal -offset indent
299 mdconfig -f diskimage.img -u md1
300 gnop create -o 512K md1
301 mount /dev/md1.nop /mnt
313 utility first appeared in
315 as a cleaner replacement for the
323 utility was written by
324 .An Poul-Henning Kamp
325 .Aq phk@FreeBSD.org .