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. 4.\" Copyright (c) 2000 5.\" Poul-Henning Kamp All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" the Systems Programming Group of the University of Utah Computer 9.\" Science Department. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. All advertising materials mentioning features or use of this software 20.\" must display the following acknowledgement: 21.\" This product includes software developed by the University of 22.\" California, Berkeley and its contributors. 23.\" 4. Neither the name of the University nor the names of its contributors 24.\" may be used to endorse or promote products derived from this software 25.\" without specific prior written permission. 26.\" 27.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37.\" SUCH DAMAGE. 38.\" 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 41.\" 42.\" $FreeBSD$ 43.\" 44.Dd June 21, 2008 45.Dt MDCONFIG 8 46.Os 47.Sh NAME 48.Nm mdconfig 49.Nd configure and enable memory disks 50.Sh SYNOPSIS 51.Nm 52.Fl a 53.Fl t Ar type 54.Op Fl n 55.Oo Fl o Oo Cm no Oc Ns Ar option Oc ... 56.Op Fl f Ar file 57.Op Fl s Ar size 58.Op Fl S Ar sectorsize 59.Op Fl u Ar unit 60.Op Fl x Ar sectors/track 61.Op Fl y Ar heads/cylinder 62.Nm 63.Fl d 64.Fl u Ar unit 65.Op Fl o Oo Cm no Oc Ns Ar force 66.Nm 67.Fl l 68.Op Fl n 69.Op Fl v 70.Op Fl u Ar unit 71.Nm 72.Ar file 73.Sh DESCRIPTION 74The 75.Nm 76utility configures and enables 77.Xr md 4 78devices. 79.Pp 80Options indicate an action to be performed: 81.Bl -tag -width indent 82.It Fl a 83Attach a memory disk. 84This will configure and attach a memory disk with the 85parameters specified and attach it to the system. 86.It Fl d 87Detach a memory disk from the system and release all resources. 88.It Fl t Ar type 89Select the type of the memory disk. 90.Bl -tag -width "preload" 91.It Cm malloc 92Storage for this type of memory disk is allocated with 93.Xr malloc 9 . 94This limits the size to the malloc bucket limit in the kernel. 95If the 96.Fl o Cm reserve 97option is not set, creating and filling a large 98malloc-backed memory disk is a very easy way to 99panic a system. 100.It Cm vnode 101A file specified with 102.Fl f Ar file 103becomes the backing store for this memory disk. 104.It Cm swap 105Storage for this type of memory disk is allocated from buffer 106memory. 107Pages get pushed out to the swap when the system is under memory 108pressure, otherwise they stay in the operating memory. 109Using 110.Cm swap 111backing is generally preferable over 112.Cm malloc 113backing. 114.El 115.It Fl f Ar file 116Filename to use for the vnode type memory disk. Options 117.Fl a 118and 119.Fl t Ar vnode 120are implied if not specified. 121.It Fl l 122List configured devices. 123If given with 124.Fl u , 125display details about that particular device. 126If 127.Fl v 128option specified, show all details. 129.It Fl n 130When printing md device names, print only the unit number without the 131md prefix. 132.It Fl s Ar size 133Size of the memory disk. 134.Ar Size 135is the number of 512 byte sectors unless suffixed with a 136.Cm b , k , m , g , 137or 138.Cm t 139which 140denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. Options 141.Fl a 142and 143.Fl t Ar swap 144are implied if not specified. 145.It Fl S Ar sectorsize 146Sectorsize to use for malloc backed device. 147.It Fl x Ar sectors/track 148See the description of the 149.Fl y 150option below. 151.It Fl y Ar heads/cylinder 152For 153.Cm malloc 154or 155.Cm vnode 156backed devices, the 157.Fl x 158and 159.Fl y 160options can be used to specify a synthetic geometry. 161This is useful for constructing bootable images for later download to 162other devices. 163.It Fl o Oo Cm no Oc Ns Ar option 164Set or reset options. 165.Bl -tag -width indent 166.It Oo Cm no Oc Ns Cm async 167For 168.Cm vnode 169backed devices: avoid 170.Dv IO_SYNC 171for increased performance but 172at the risk of deadlocking the entire kernel. 173.It Oo Cm no Oc Ns Cm reserve 174Allocate and reserve all needed storage from the start, rather than as needed. 175.It Oo Cm no Oc Ns Cm cluster 176Enable clustering on this disk. 177.It Oo Cm no Oc Ns Cm compress 178Enable/Disable compression features to reduce memory usage. 179.It Oo Cm no Oc Ns Cm force 180Disable/Enable extra sanity checks to prevent the user from doing something 181that might adversely affect the system. 182.It Oo Cm no Oc Ns Cm readonly 183Enable/Disable readonly mode. 184.El 185.It Fl u Ar unit 186Request a specific unit number for the 187.Xr md 4 188device instead of automatic allocation. 189.El 190.Pp 191The last form, 192.Nm 193.Ar file , 194is provided for convenience as an abbreviation of 195.Nm 196.Fl a 197.Fl t Ar vnode 198.Fl f Ar file . 199.Sh EXAMPLES 200To create a 4 megabyte 201.Xr malloc 9 202backed memory disk. 203The name of the allocated unit will be output on stdout like 204.Dq Li md3 : 205.Pp 206.Dl mdconfig -a -t malloc -s 4m 207.Pp 208To create a disk named 209.Pa /dev/md4 210with 211.Pa /tmp/boot.flp 212as backing storage: 213.Pp 214.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4 215.Pp 216To detach and free all resources used by 217.Pa /dev/md4 : 218.Pp 219.Dl mdconfig -d -u 4 220.Pp 221To create a 128MByte swap backed disk, initialize an 222.Xr ffs 7 223file system on it, and mount it on 224.Pa /tmp : 225.Bd -literal -offset indent 226mdconfig -a -t swap -s 128M -u 10 227newfs -U /dev/md10 228mount /dev/md10 /tmp 229chmod 1777 /tmp 230.Ed 231.Pp 232To create a 5MB file-backed disk 233.Ns ( Fl a 234and 235.Fl t Ar vnode 236are implied): 237.Bd -literal -offset indent 238dd if=/dev/zero of=somebackingfile bs=1k count=5k 239mdconfig -f somebackingfile -u 0 240bsdlabel -w md0 auto 241newfs md0c 242mount /dev/md0c /mnt 243.Ed 244.Pp 245To create an 246.Xr md 4 247device out of an ISO 9660 CD image file 248.Ns ( Fl a 249and 250.Fl t Ar vnode 251are implied), using the first available 252.Xr md 4 253device, and then mount the new memory disk: 254.Bd -literal -offset indent 255mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 256.Ed 257.Sh SEE ALSO 258.Xr md 4 , 259.Xr ffs 7 , 260.Xr bsdlabel 8 , 261.Xr fdisk 8 , 262.Xr mdmfs 8 , 263.Xr malloc 9 264.Sh HISTORY 265The 266.Nm 267utility first appeared in 268.Fx 5.0 269as a cleaner replacement for the 270.Xr vn 4 271and 272.Xr vnconfig 8 273combo. 274.Sh AUTHORS 275The 276.Nm 277utility was written by 278.An Poul-Henning Kamp 279.Aq phk@FreeBSD.org . 280