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 October 26, 2013 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 r 68.Fl u Ar unit 69.Fl s Ar size 70.Op Fl o Oo Cm no Oc Ns Ar force 71.Nm 72.Fl l 73.Op Fl n 74.Op Fl v 75.Op Fl f Ar file 76.Op Fl u Ar unit 77.Nm 78.Ar file 79.Sh DESCRIPTION 80The 81.Nm 82utility configures and enables 83.Xr md 4 84devices. 85.Pp 86Options indicate an action to be performed: 87.Bl -tag -width indent 88.It Fl a 89Attach a memory disk. 90This will configure and attach a memory disk with the 91parameters specified and attach it to the system. 92If the 93.Fl u Ar unit 94option is not provided, the newly created device name will be printed on stdout. 95.It Fl d 96Detach a memory disk from the system and release all resources. 97.It Fl r 98Resize a memory disk. 99.It Fl t Ar type 100Select the type of the memory disk. 101.Bl -tag -width "malloc" 102.It Cm malloc 103Storage for this type of memory disk is allocated with 104.Xr malloc 9 . 105This limits the size to the malloc bucket limit in the kernel. 106If the 107.Fl o Cm reserve 108option is not set, creating and filling a large 109malloc-backed memory disk is a very easy way to 110panic a system. 111.It Cm vnode 112A file specified with 113.Fl f Ar file 114becomes the backing store for this memory disk. 115.It Cm swap 116Storage for this type of memory disk is allocated from buffer 117memory. 118Pages get pushed out to swap when the system is under memory 119pressure, otherwise they stay in the operating memory. 120Using 121.Cm swap 122backing is generally preferred instead of using 123.Cm malloc 124backing. 125.El 126.It Fl f Ar file 127Filename to use for the vnode type memory disk. 128The 129.Fl a 130and 131.Fl t Ar vnode 132options are implied if not specified. 133.It Fl l 134List configured devices. 135If given with 136.Fl u , 137display details about that particular device. 138If given with 139.Fl f Ar file , 140display 141.Xr md 4 142device names of which 143.Ar file 144is used as the backing store. 145If both of 146.Fl u 147and 148.Fl f 149options are specified, 150display devices which match the two conditions. 151If the 152.Fl v 153option is specified, show all details. 154.It Fl n 155When printing 156.Xr md 4 157device names, print only the unit number without the 158.Xr md 4 159prefix. 160.It Fl s Ar size 161Size of the memory disk. 162.Ar Size 163is the number of 512 byte sectors unless suffixed with a 164.Cm b , k , m , g , 165or 166.Cm t 167which 168denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. 169The 170.Fl a 171and 172.Fl t Ar swap 173options are implied if not specified. 174.It Fl S Ar sectorsize 175Sectorsize to use for the memory disk, in bytes. 176.It Fl x Ar sectors/track 177See the description of the 178.Fl y 179option below. 180.It Fl y Ar heads/cylinder 181For 182.Cm malloc 183or 184.Cm vnode 185backed devices, the 186.Fl x 187and 188.Fl y 189options can be used to specify a synthetic geometry. 190This is useful for constructing bootable images for later download to 191other devices. 192.It Fl o Oo Cm no Oc Ns Ar option 193Set or reset options. 194.Bl -tag -width indent 195.It Oo Cm no Oc Ns Cm async 196For 197.Cm vnode 198backed devices: avoid 199.Dv IO_SYNC 200for increased performance but 201at the risk of deadlocking the entire kernel. 202.It Oo Cm no Oc Ns Cm reserve 203Allocate and reserve all needed storage from the start, rather than as needed. 204.It Oo Cm no Oc Ns Cm cluster 205Enable clustering on this disk. 206.It Oo Cm no Oc Ns Cm compress 207Enable/disable compression features to reduce memory usage. 208.It Oo Cm no Oc Ns Cm force 209Disable/enable extra sanity checks to prevent the user from doing something 210that might adversely affect the system. 211.It Oo Cm no Oc Ns Cm readonly 212Enable/disable readonly mode. 213.El 214.It Fl u Ar unit 215Request a specific unit number or device name for the 216.Xr md 4 217device instead of automatic allocation. 218If a device name is specified, it must be start with 219.Dq md 220followed by the unit number. 221.El 222.Pp 223The last form, 224.Nm 225.Ar file , 226is provided for convenience as an abbreviation of 227.Nm 228.Fl a 229.Fl t Ar vnode 230.Fl f Ar file . 231.Sh EXAMPLES 232Create a 4 megabyte 233.Xr malloc 9 234backed memory disk. 235The name of the allocated unit will be printed on stdout, such as 236.Dq Li md3 : 237.Pp 238.Dl mdconfig -a -t malloc -s 4m 239.Pp 240Create a disk named 241.Pa /dev/md4 242with 243.Pa /tmp/boot.flp 244as backing storage: 245.Pp 246.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u md4 247.Pp 248Detach and free all resources used by 249.Pa /dev/md4 : 250.Pp 251.Dl mdconfig -d -u md4 252.Pp 253Create a 128MByte swap backed disk, initialize an 254.Xr ffs 7 255file system on it, and mount it on 256.Pa /tmp : 257.Bd -literal -offset indent 258mdconfig -a -t swap -s 128M -u md10 259newfs -U /dev/md10 260mount /dev/md10 /tmp 261chmod 1777 /tmp 262.Ed 263.Pp 264Create a 5MB file-backed disk 265.Po Fl a 266and 267.Fl t Ar vnode 268are implied 269.Pc : 270.Bd -literal -offset indent 271dd if=/dev/zero of=somebackingfile bs=1k count=5k 272mdconfig -f somebackingfile -u md0 273bsdlabel -w md0 auto 274newfs md0c 275mount /dev/md0c /mnt 276.Ed 277.Pp 278Create an 279.Xr md 4 280device out of an ISO 9660 CD image file 281.Po Fl a 282and 283.Fl t Ar vnode 284are implied 285.Pc , using the first available 286.Xr md 4 287device, and then mount the new memory disk: 288.Bd -literal -offset indent 289mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 290.Pp 291.Ed 292Create a file-backed device from a hard disk image that begins 293with 512K of raw header information. 294.Xr gnop 8 295is used to skip over the header information, positioning 296.Pa md1.nop 297to the start of the filesystem in the image. 298.Bd -literal -offset indent 299mdconfig -f diskimage.img -u md1 300gnop create -o 512K md1 301mount /dev/md1.nop /mnt 302.Ed 303.Sh SEE ALSO 304.Xr md 4 , 305.Xr ffs 7 , 306.Xr bsdlabel 8 , 307.Xr fdisk 8 , 308.Xr mdmfs 8 , 309.Xr malloc 9 310.Sh HISTORY 311The 312.Nm 313utility first appeared in 314.Fx 5.0 315as a cleaner replacement for the 316.Xr vn 4 317and 318.Xr vnconfig 8 319combo. 320.Sh AUTHORS 321The 322.Nm 323utility was written by 324.An Poul-Henning Kamp 325.Aq phk@FreeBSD.org . 326