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.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.Sh DESCRIPTION 72The 73.Nm 74utility configures and enables 75.Xr md 4 76devices. 77.Pp 78Options indicate an action to be performed: 79.Bl -tag -width indent 80.It Fl a 81Attach a memory disk. 82This will configure and attach a memory disk with the 83parameters specified and attach it to the system. 84.It Fl d 85Detach a memory disk from the system and release all resources. 86.It Fl t Ar type 87Select the type of the memory disk. 88.Bl -tag -width "preload" 89.It Cm malloc 90Storage for this type of memory disk is allocated with 91.Xr malloc 9 . 92This limits the size to the malloc bucket limit in the kernel. 93If the 94.Fl o Cm reserve 95option is not set, creating and filling a large 96malloc-backed memory disk is a very easy way to 97panic a system. 98.It Cm vnode 99A file specified with 100.Fl f Ar file 101becomes the backing store for this memory disk. 102.It Cm swap 103Storage for this type of memory disk is allocated from buffer 104memory. 105Pages get pushed out to the swap when the system is under memory 106pressure, otherwise they stay in the operating memory. 107Using 108.Cm swap 109backing is generally preferable over 110.Cm malloc 111backing. 112.El 113.It Fl f Ar file 114Filename to use for the vnode type memory disk. Options 115.Fl a 116and 117.Fl t Ar vnode 118are implied if not specified. 119.It Fl l 120List configured devices. 121If given with 122.Fl u , 123display details about that particular device. 124If 125.Fl v 126option specified, show all details. 127.It Fl n 128When printing md device names, print only the unit number without the 129md prefix. 130.It Fl s Ar size 131Size of the memory disk. 132.Ar Size 133is the number of 512 byte sectors unless suffixed with a 134.Cm b , k , m , g , 135or 136.Cm t 137which 138denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. Options 139.Fl a 140and 141.Fl t Ar swap 142are implied if not specified. 143.It Fl S Ar sectorsize 144Sectorsize to use for malloc backed device. 145.It Fl x Ar sectors/track 146See the description of the 147.Fl y 148option below. 149.It Fl y Ar heads/cylinder 150For 151.Cm malloc 152or 153.Cm vnode 154backed devices, the 155.Fl x 156and 157.Fl y 158options can be used to specify a synthetic geometry. 159This is useful for constructing bootable images for later download to 160other devices. 161.It Fl o Oo Cm no Oc Ns Ar option 162Set or reset options. 163.Bl -tag -width indent 164.It Oo Cm no Oc Ns Cm async 165For 166.Cm vnode 167backed devices: avoid 168.Dv IO_SYNC 169for increased performance but 170at the risk of deadlocking the entire kernel. 171.It Oo Cm no Oc Ns Cm reserve 172Allocate and reserve all needed storage from the start, rather than as needed. 173.It Oo Cm no Oc Ns Cm cluster 174Enable clustering on this disk. 175.It Oo Cm no Oc Ns Cm compress 176Enable/Disable compression features to reduce memory usage. 177.It Oo Cm no Oc Ns Cm force 178Disable/Enable extra sanity checks to prevent the user from doing something 179that might adversely affect the system. 180.It Oo Cm no Oc Ns Cm readonly 181Enable/Disable readonly mode. 182.El 183.It Fl u Ar unit 184Request a specific unit number for the 185.Xr md 4 186device instead of automatic allocation. 187.El 188.Sh EXAMPLES 189To create a 4 megabyte 190.Xr malloc 9 191backed memory disk. 192The name of the allocated unit will be output on stdout like 193.Dq Li md3 : 194.Pp 195.Dl mdconfig -a -t malloc -s 4m 196.Pp 197To create a disk named 198.Pa /dev/md4 199with 200.Pa /tmp/boot.flp 201as backing storage: 202.Pp 203.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4 204.Pp 205To detach and free all resources used by 206.Pa /dev/md4 : 207.Pp 208.Dl mdconfig -d -u 4 209.Pp 210To create a 128MByte swap backed disk, initialize an 211.Xr ffs 7 212file system on it, and mount it on 213.Pa /tmp : 214.Bd -literal -offset indent 215mdconfig -a -t swap -s 128M -u 10 216newfs -U /dev/md10 217mount /dev/md10 /tmp 218chmod 1777 /tmp 219.Ed 220.Pp 221To create a 5MB file-backed disk 222.Ns ( Fl a 223and 224.Fl t Ar vnode 225are implied): 226.Bd -literal -offset indent 227dd if=/dev/zero of=somebackingfile bs=1k count=5k 228mdconfig -f somebackingfile -u 0 229bsdlabel -w md0 auto 230newfs md0c 231mount /dev/md0c /mnt 232.Ed 233.Pp 234To create an 235.Xr md 4 236device out of an ISO 9660 CD image file 237.Ns ( Fl a 238and 239.Fl t Ar vnode 240are implied), using the first available 241.Xr md 4 242device, and then mount the new memory disk: 243.Bd -literal -offset indent 244mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 245.Ed 246.Sh SEE ALSO 247.Xr md 4 , 248.Xr ffs 7 , 249.Xr bsdlabel 8 , 250.Xr fdisk 8 , 251.Xr mdmfs 8 , 252.Xr malloc 9 253.Sh HISTORY 254The 255.Nm 256utility first appeared in 257.Fx 5.0 258as a cleaner replacement for the 259.Xr vn 4 260and 261.Xr vnconfig 8 262combo. 263.Sh AUTHORS 264The 265.Nm 266utility was written by 267.An Poul-Henning Kamp 268.Aq phk@FreeBSD.org . 269