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 November 30, 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.It Cm null 126Bitsink; all writes do nothing, all reads return zeroes. 127.El 128.It Fl f Ar file 129Filename to use for the vnode type memory disk. 130The 131.Fl a 132and 133.Fl t Ar vnode 134options are implied if not specified. 135.It Fl l 136List configured devices. 137If given with 138.Fl u , 139display details about that particular device. 140If given with 141.Fl f Ar file , 142display 143.Xr md 4 144device names of which 145.Ar file 146is used as the backing store. 147If both of 148.Fl u 149and 150.Fl f 151options are specified, 152display devices which match the two conditions. 153If the 154.Fl v 155option is specified, show all details. 156.It Fl n 157When printing 158.Xr md 4 159device names, print only the unit number without the 160.Xr md 4 161prefix. 162.It Fl s Ar size 163Size of the memory disk. 164.Ar Size 165is the number of 512 byte sectors unless suffixed with a 166.Cm b , k , m , g , 167or 168.Cm t 169which 170denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. 171The 172.Fl a 173and 174.Fl t Ar swap 175options are implied if not specified. 176.It Fl S Ar sectorsize 177Sectorsize to use for the memory disk, in bytes. 178.It Fl x Ar sectors/track 179See the description of the 180.Fl y 181option below. 182.It Fl y Ar heads/cylinder 183For 184.Cm malloc 185or 186.Cm vnode 187backed devices, the 188.Fl x 189and 190.Fl y 191options can be used to specify a synthetic geometry. 192This is useful for constructing bootable images for later download to 193other devices. 194.It Fl o Oo Cm no Oc Ns Ar option 195Set or reset options. 196.Bl -tag -width indent 197.It Oo Cm no Oc Ns Cm async 198For 199.Cm vnode 200backed devices: avoid 201.Dv IO_SYNC 202for increased performance but 203at the risk of deadlocking the entire kernel. 204.It Oo Cm no Oc Ns Cm reserve 205Allocate and reserve all needed storage from the start, rather than as needed. 206.It Oo Cm no Oc Ns Cm cluster 207Enable clustering on this disk. 208.It Oo Cm no Oc Ns Cm compress 209Enable/disable compression features to reduce memory usage. 210.It Oo Cm no Oc Ns Cm force 211Disable/enable extra sanity checks to prevent the user from doing something 212that might adversely affect the system. 213.It Oo Cm no Oc Ns Cm readonly 214Enable/disable readonly mode. 215.El 216.It Fl u Ar unit 217Request a specific unit number or device name for the 218.Xr md 4 219device instead of automatic allocation. 220If a device name is specified, it must be start with 221.Dq md 222followed by the unit number. 223.El 224.Pp 225The last form, 226.Nm 227.Ar file , 228is provided for convenience as an abbreviation of 229.Nm 230.Fl a 231.Fl t Ar vnode 232.Fl f Ar file . 233.Sh EXAMPLES 234Create a 4 megabyte 235.Xr malloc 9 236backed memory disk. 237The name of the allocated unit will be printed on stdout, such as 238.Dq Li md3 : 239.Pp 240.Dl mdconfig -a -t malloc -s 4m 241.Pp 242Create a disk named 243.Pa /dev/md4 244with 245.Pa /tmp/boot.flp 246as backing storage: 247.Pp 248.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u md4 249.Pp 250Detach and free all resources used by 251.Pa /dev/md4 : 252.Pp 253.Dl mdconfig -d -u md4 254.Pp 255Create a 128MByte swap backed disk, initialize an 256.Xr ffs 7 257file system on it, and mount it on 258.Pa /tmp : 259.Bd -literal -offset indent 260mdconfig -a -t swap -s 128M -u md10 261newfs -U /dev/md10 262mount /dev/md10 /tmp 263chmod 1777 /tmp 264.Ed 265.Pp 266Create a 5MB file-backed disk 267.Po Fl a 268and 269.Fl t Ar vnode 270are implied 271.Pc : 272.Bd -literal -offset indent 273dd if=/dev/zero of=somebackingfile bs=1k count=5k 274mdconfig -f somebackingfile -u md0 275bsdlabel -w md0 auto 276newfs md0c 277mount /dev/md0c /mnt 278.Ed 279.Pp 280Create an 281.Xr md 4 282device out of an ISO 9660 CD image file 283.Po Fl a 284and 285.Fl t Ar vnode 286are implied 287.Pc , using the first available 288.Xr md 4 289device, and then mount the new memory disk: 290.Bd -literal -offset indent 291mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 292.Pp 293.Ed 294Create a file-backed device from a hard disk image that begins 295with 512K of raw header information. 296.Xr gnop 8 297is used to skip over the header information, positioning 298.Pa md1.nop 299to the start of the filesystem in the image. 300.Bd -literal -offset indent 301mdconfig -f diskimage.img -u md1 302gnop create -o 512K md1 303mount /dev/md1.nop /mnt 304.Ed 305.Sh SEE ALSO 306.Xr md 4 , 307.Xr ffs 7 , 308.Xr bsdlabel 8 , 309.Xr fdisk 8 , 310.Xr mdmfs 8 , 311.Xr malloc 9 312.Sh HISTORY 313The 314.Nm 315utility first appeared in 316.Fx 5.0 317as a cleaner replacement for the 318.Xr vn 4 319and 320.Xr vnconfig 8 321combo. 322.Sh AUTHORS 323The 324.Nm 325utility was written by 326.An Poul-Henning Kamp 327.Aq phk@FreeBSD.org . 328