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.
93 Detach a memory disk from the system and release all resources.
97 Select the type of the memory disk.
98 .Bl -tag -width "malloc"
100 Storage for this type of memory disk is allocated with
102 This limits the size to the malloc bucket limit in the kernel.
105 option is not set, creating and filling a large
106 malloc-backed memory disk is a very easy way to
109 A file specified with
111 becomes the backing store for this memory disk.
113 Storage for this type of memory disk is allocated from buffer
115 Pages get pushed out to swap when the system is under memory
116 pressure, otherwise they stay in the operating memory.
119 backing is generally preferred instead of using
124 Filename to use for the vnode type memory disk.
129 options are implied if not specified.
131 List configured devices.
134 display details about that particular device.
139 device names of which
141 is used as the backing store.
146 options are specified,
147 display devices which match the two conditions.
150 option is specified, show all details.
154 device names, print only the unit number without the
158 Size of the memory disk.
160 is the number of 512 byte sectors unless suffixed with a
165 denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
170 options are implied if not specified.
171 .It Fl S Ar sectorsize
172 Sectorsize to use for the memory disk, in bytes.
173 .It Fl x Ar sectors/track
174 See the description of the
177 .It Fl y Ar heads/cylinder
186 options can be used to specify a synthetic geometry.
187 This is useful for constructing bootable images for later download to
189 .It Fl o Oo Cm no Oc Ns Ar option
190 Set or reset options.
191 .Bl -tag -width indent
192 .It Oo Cm no Oc Ns Cm async
195 backed devices: avoid
197 for increased performance but
198 at the risk of deadlocking the entire kernel.
199 .It Oo Cm no Oc Ns Cm reserve
200 Allocate and reserve all needed storage from the start, rather than as needed.
201 .It Oo Cm no Oc Ns Cm cluster
202 Enable clustering on this disk.
203 .It Oo Cm no Oc Ns Cm compress
204 Enable/disable compression features to reduce memory usage.
205 .It Oo Cm no Oc Ns Cm force
206 Disable/enable extra sanity checks to prevent the user from doing something
207 that might adversely affect the system.
208 .It Oo Cm no Oc Ns Cm readonly
209 Enable/disable readonly mode.
212 Request a specific unit number for the
214 device instead of automatic allocation.
220 is provided for convenience as an abbreviation of
229 The name of the allocated unit will be printed on stdout, such as
232 .Dl mdconfig -a -t malloc -s 4m
240 .Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4
242 Detach and free all resources used by
247 Create a 128MByte swap backed disk, initialize an
249 file system on it, and mount it on
251 .Bd -literal -offset indent
252 mdconfig -a -t swap -s 128M -u 10
258 Create a 5MB file-backed disk
264 .Bd -literal -offset indent
265 dd if=/dev/zero of=somebackingfile bs=1k count=5k
266 mdconfig -f somebackingfile -u 0
274 device out of an ISO 9660 CD image file
279 .Pc , using the first available
281 device, and then mount the new memory disk:
282 .Bd -literal -offset indent
283 mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
286 Create a file-backed device from a hard disk image that begins
287 with 512K of raw header information.
289 is used to skip over the header information, positioning
291 to the start of the filesystem in the image.
292 .Bd -literal -offset indent
293 mdconfig -f diskimage.img -u 1
294 gnop create -o 512K md1
295 mount /dev/md1.nop /mnt
307 utility first appeared in
309 as a cleaner replacement for the
317 utility was written by
318 .An Poul-Henning Kamp
319 .Aq phk@FreeBSD.org .