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
126 Bitsink; all writes do nothing, all reads return zeroes.
129 Filename to use for the vnode type memory disk.
134 options are implied if not specified.
136 List configured devices.
139 display details about that particular device.
144 device names of which
146 is used as the backing store.
151 options are specified,
152 display devices which match the two conditions.
155 option is specified, show all details.
159 device names, print only the unit number without the
163 Size of the memory disk.
165 is the number of 512 byte sectors unless suffixed with a
170 denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
175 options are implied if not specified.
176 .It Fl S Ar sectorsize
177 Sectorsize to use for the memory disk, in bytes.
178 .It Fl x Ar sectors/track
179 See the description of the
182 .It Fl y Ar heads/cylinder
191 options can be used to specify a synthetic geometry.
192 This is useful for constructing bootable images for later download to
194 .It Fl o Oo Cm no Oc Ns Ar option
195 Set or reset options.
196 .Bl -tag -width indent
197 .It Oo Cm no Oc Ns Cm async
200 backed devices: avoid
202 for increased performance but
203 at the risk of deadlocking the entire kernel.
204 .It Oo Cm no Oc Ns Cm reserve
205 Allocate and reserve all needed storage from the start, rather than as needed.
206 .It Oo Cm no Oc Ns Cm cluster
207 Enable clustering on this disk.
208 .It Oo Cm no Oc Ns Cm compress
209 Enable/disable compression features to reduce memory usage.
210 .It Oo Cm no Oc Ns Cm force
211 Disable/enable extra sanity checks to prevent the user from doing something
212 that might adversely affect the system.
213 .It Oo Cm no Oc Ns Cm readonly
214 Enable/disable readonly mode.
217 Request a specific unit number or device name for the
219 device instead of automatic allocation.
220 If a device name is specified, it must be start with
222 followed by the unit number.
228 is provided for convenience as an abbreviation of
237 The name of the allocated unit will be printed on stdout, such as
240 .Dl mdconfig -a -t malloc -s 4m
248 .Dl mdconfig -a -t vnode -f /tmp/boot.flp -u md4
250 Detach and free all resources used by
253 .Dl mdconfig -d -u md4
255 Create a 128MByte swap backed disk, initialize an
257 file system on it, and mount it on
259 .Bd -literal -offset indent
260 mdconfig -a -t swap -s 128M -u md10
266 Create a 5MB file-backed disk
272 .Bd -literal -offset indent
273 dd if=/dev/zero of=somebackingfile bs=1k count=5k
274 mdconfig -f somebackingfile -u md0
282 device out of an ISO 9660 CD image file
287 .Pc , using the first available
289 device, and then mount the new memory disk:
290 .Bd -literal -offset indent
291 mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
294 Create a file-backed device from a hard disk image that begins
295 with 512K of raw header information.
297 is used to skip over the header information, positioning
299 to the start of the filesystem in the image.
300 .Bd -literal -offset indent
301 mdconfig -f diskimage.img -u md1
302 gnop create -o 512K md1
303 mount /dev/md1.nop /mnt
315 utility first appeared in
317 as a cleaner replacement for the
325 utility was written by
326 .An Poul-Henning Kamp
327 .Aq phk@FreeBSD.org .