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/cyl 62.Nm 63.Fl d 64.Fl u Ar unit 65.Nm 66.Fl l 67.Op Fl n 68.Op Fl v 69.Op Fl u Ar unit 70.Sh DESCRIPTION 71The 72.Nm 73utility configures and enables 74.Xr md 4 75devices. 76.Pp 77Options indicate an action to be performed: 78.Bl -tag -width indent 79.It Fl a 80Attach a memory disk. 81This will configure and attach a memory disk with the 82parameters specified and attach it to the system. 83.It Fl d 84Detach a memory disk from the system and release all resources. 85.It Fl t Ar type 86Select the type of the memory disk. 87.Bl -tag -width "preload" 88.It Cm malloc 89Storage for this type of memory disk is allocated with 90.Xr malloc 9 . 91This limits the size to the malloc bucket limit in the kernel. 92If the 93.Fl o Cm reserve 94option is not set, creating and filling a large 95malloc-backed memory disk is a very easy way to 96panic a system. 97.It Cm vnode 98A file specified with 99.Fl f Ar file 100becomes the backing store for this memory disk. 101.It Cm swap 102Storage for this type of memory disk is allocated from buffer 103memory. 104Pages get pushed out to the swap when the system is under memory 105pressure, otherwise they stay in the operating memory. 106Using 107.Cm swap 108backing is generally preferable over 109.Cm malloc 110backing. 111.El 112.It Fl f Ar file 113Filename to use for the vnode type memory disk. Options 114.Fl a 115and 116.Fl t Ar vnode 117are implied if not specified. 118.It Fl l 119List configured devices. 120If given with 121.Fl u , 122display details about that particular device. 123If 124.Fl v 125option specified, show all details. 126.It Fl n 127When printing md device names, print only the unit number without the 128md prefix. 129.It Fl s Ar size 130Size of the memory disk. 131.Ar Size 132is the number of 512 byte sectors unless suffixed with a 133.Cm b , k , m , g , 134or 135.Cm t 136which 137denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. Options 138.Fl a 139and 140.Fl t Ar swap 141are implied if not specified. 142.It Fl S Ar sectorsize 143Sectorsize to use for malloc backed device. 144.It Fl x Ar sectors/track 145See the description of the 146.Fl y 147option below. 148.It Fl y Ar heads/cylinder 149For 150.Cm malloc 151or 152.Cm vnode 153backed devices, the 154.Fl x 155and 156.Fl y 157options can be used to specify a synthetic geometry. 158This is useful for constructing bootable images for later download to 159other devices. 160.It Fl o Oo Cm no Oc Ns Ar option 161Set or reset options. 162.Bl -tag -width indent 163.It Oo Cm no Oc Ns Cm async 164For 165.Cm vnode 166backed devices: avoid 167.Dv IO_SYNC 168for increased performance but 169at the risk of deadlocking the entire kernel. 170.It Oo Cm no Oc Ns Cm reserve 171Allocate and reserve all needed storage from the start, rather than as needed. 172.It Oo Cm no Oc Ns Cm cluster 173Enable clustering on this disk. 174.It Oo Cm no Oc Ns Cm compress 175Enable/Disable compression features to reduce memory usage. 176.It Oo Cm no Oc Ns Cm force 177Disable/Enable extra sanity checks to prevent the user from doing something 178that might adversely affect the system. 179.It Oo Cm no Oc Ns Cm readonly 180Enable/Disable readonly mode. 181.El 182.It Fl u Ar unit 183Request a specific unit number for the 184.Xr md 4 185device instead of automatic allocation. 186.El 187.Sh EXAMPLES 188To create a 4 megabyte 189.Xr malloc 9 190backed memory disk. 191The name of the allocated unit will be output on stdout like 192.Dq Li md3 : 193.Pp 194.Dl mdconfig -a -t malloc -s 4m 195.Pp 196To create a disk named 197.Pa /dev/md4 198with 199.Pa /tmp/boot.flp 200as backing storage: 201.Pp 202.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4 203.Pp 204To detach and free all resources used by 205.Pa /dev/md4 : 206.Pp 207.Dl mdconfig -d -u 4 208.Pp 209To create a 128MByte swap backed disk, initialize an 210.Xr ffs 7 211file system on it, and mount it on 212.Pa /tmp : 213.Bd -literal -offset indent 214mdconfig -a -t swap -s 128M -u 10 215newfs -U /dev/md10 216mount /dev/md10 /tmp 217chmod 1777 /tmp 218.Ed 219.Pp 220To create a 5MB file-backed disk 221.Ns ( Fl a 222and 223.Fl t Ar vnode 224are implied): 225.Bd -literal -offset indent 226dd if=/dev/zero of=somebackingfile bs=1k count=5k 227mdconfig -f somebackingfile -u 0 228bsdlabel -w md0 auto 229newfs md0c 230mount /dev/md0c /mnt 231.Ed 232.Pp 233To create an 234.Xr md 4 235device out of an ISO 9660 CD image file 236.Ns ( Fl a 237and 238.Fl t Ar vnode 239are implied), using the first available 240.Xr md 4 241device, and then mount the new memory disk: 242.Bd -literal -offset indent 243mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 244.Ed 245.Sh SEE ALSO 246.Xr md 4 , 247.Xr ffs 7 , 248.Xr bsdlabel 8 , 249.Xr fdisk 8 , 250.Xr mdmfs 8 , 251.Xr malloc 9 252.Sh HISTORY 253The 254.Nm 255utility first appeared in 256.Fx 5.0 257as a cleaner replacement for the 258.Xr vn 4 259and 260.Xr vnconfig 8 261combo. 262.Sh AUTHORS 263The 264.Nm 265utility was written by 266.An Poul-Henning Kamp 267.Aq phk@FreeBSD.org . 268