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. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93 36.\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29 37.\" 38.\" $FreeBSD$ 39.\" 40.Dd August 28, 2017 41.Dt MDCONFIG 8 42.Os 43.Sh NAME 44.Nm mdconfig 45.Nd create and control memory disks 46.Sh SYNOPSIS 47.Nm 48.Fl a 49.Fl t Ar type 50.Op Fl n 51.Oo Fl o Oo Cm no Oc Ns Ar option Oc ... 52.Op Fl f Ar file 53.Op Fl s Ar size 54.Op Fl S Ar sectorsize 55.Op Fl u Ar unit 56.Op Fl x Ar sectors/track 57.Op Fl y Ar heads/cylinder 58.Op Fl L Ar label 59.Nm 60.Fl d 61.Fl u Ar unit 62.Op Fl o Oo Cm no Oc Ns Ar force 63.Nm 64.Fl r 65.Fl u Ar unit 66.Fl s Ar size 67.Op Fl o Oo Cm no Oc Ns Ar force 68.Nm 69.Fl l 70.Op Fl n 71.Op Fl v 72.Op Fl f Ar file 73.Op Fl u Ar unit 74.Nm 75.Ar file 76.Sh DESCRIPTION 77The 78.Nm 79utility creates and controls 80.Xr md 4 81devices. 82.Pp 83Options indicate an action to be performed: 84.Bl -tag -width indent 85.It Fl a 86Attach a memory disk. 87This will configure and attach a memory disk with the 88parameters specified and attach it to the system. 89If the 90.Fl u Ar unit 91option is not provided, the newly created device name will be printed on stdout. 92.It Fl d 93Detach a memory disk from the system and release all resources. 94.It Fl r 95Resize a memory disk. 96.It Fl t Ar type 97Select the type of the memory disk. 98.Bl -tag -width "malloc" 99.It Cm malloc 100Storage for this type of memory disk is allocated with 101.Xr malloc 9 . 102This limits the size to the malloc bucket limit in the kernel. 103If the 104.Fl o Cm reserve 105option is not set, creating and filling a large 106malloc-backed memory disk is a very easy way to 107panic the system. 108.It Cm vnode 109A file specified with 110.Fl f Ar file 111becomes the backing store for this memory disk. 112.It Cm swap 113Storage for this type of memory disk is allocated from buffer 114memory. 115Pages get pushed out to swap when the system is under memory 116pressure, otherwise they stay in the operating memory. 117Using 118.Cm swap 119backing is generally preferred instead of using 120.Cm malloc 121backing. 122.It Cm null 123Bitsink; all writes do nothing, all reads return zeroes. 124.El 125.It Fl f Ar file 126Filename to use for the vnode type memory disk. 127The 128.Fl a 129and 130.Fl t Ar vnode 131options are implied if not specified. 132.It Fl l 133List configured devices. 134If given with 135.Fl u , 136display details about that particular device. 137If given with 138.Fl f Ar file , 139display 140.Xr md 4 141device names of which 142.Ar file 143is used as the backing store. 144If both of 145.Fl u 146and 147.Fl f 148options are specified, 149display devices which match the two conditions. 150If the 151.Fl v 152option is specified, show all details. 153.It Fl n 154When printing 155.Xr md 4 156device names, print only the unit number without the 157.Xr md 4 158prefix. 159.It Fl s Ar size 160Size of the memory disk. 161.Ar Size 162is the number of 512 byte sectors unless suffixed with a 163.Cm b , k , m , g , t , 164or 165.Cm p 166which 167denotes byte, kilobyte, megabyte, gigabyte, terabyte and petabyte respectively. 168When used without the 169.Fl r 170option, the 171.Fl a 172and 173.Fl t Ar swap 174options are implied if not specified. 175.It Fl S Ar sectorsize 176Sectorsize to use for the memory disk, in bytes. 177.It Fl x Ar sectors/track 178See the description of the 179.Fl y 180option below. 181.It Fl y Ar heads/cylinder 182For 183.Cm malloc 184or 185.Cm vnode 186backed devices, the 187.Fl x 188and 189.Fl y 190options can be used to specify a synthetic geometry. 191This is useful for constructing bootable images for later download to 192other devices. 193.It Fl L Ar label 194Associate a label (arbitrary string) with the new memory disk. 195The label can then be inspected with 196.Bd -literal -offset indent 197.Nm Fl l v 198.Ed 199.It Fl o Oo Cm no Oc Ns Ar option 200Set or reset options. 201.Bl -tag -width indent 202.It Oo Cm no Oc Ns Cm async 203For 204.Cm vnode 205backed devices: avoid 206.Dv IO_SYNC 207for increased performance but 208at the risk of deadlocking the entire kernel. 209.It Oo Cm no Oc Ns Cm reserve 210Allocate and reserve all needed storage from the start, rather than as needed. 211.It Oo Cm no Oc Ns Cm cluster 212Enable clustering on this disk. 213.It Oo Cm no Oc Ns Cm compress 214Enable/disable compression features to reduce memory usage. 215.It Oo Cm no Oc Ns Cm force 216Disable/enable extra sanity checks to prevent the user from doing something 217that might adversely affect the system. 218This can be used with the 219.Fl d 220flag to forcibly destroy an 221.Xr md 4 222disk that is still in use. 223.It Oo Cm no Oc Ns Cm readonly 224Enable/disable readonly mode. 225.It Oo Cm no Oc Ns Cm verify 226For 227.Cm vnode 228backed devices: enable/disable requesting verification of the 229file used for backing store. 230The type of verification depends on which security features are available. 231One example of verification is testing file integrity with 232checksums or cryptographic signatures. 233.El 234.It Fl u Ar unit 235Request a specific unit number or device name for the 236.Xr md 4 237device instead of automatic allocation. 238If a device name is specified, it must be start with 239.Dq md 240followed by the unit number. 241.El 242.Pp 243The last form, 244.Nm 245.Ar file , 246is provided for convenience as an abbreviation of 247.Nm 248.Fl a 249.Fl t Ar vnode 250.Fl f Ar file . 251.Sh EXAMPLES 252Create a disk with 253.Pa /tmp/boot.flp 254as backing storage. 255The name of the allocated unit will be printed on stdout, such as 256.Dq Li md0 : 257.Bd -literal -offset indent 258mdconfig /tmp/boot.flp 259.Ed 260.Pp 261Create a 1 gigabyte swap backed memory disk named 262.Dq Li md3 : 263.Bd -literal -offset indent 264mdconfig -s 1g -u md3 265.Ed 266.Pp 267Detach and free all resources used by 268.Pa /dev/md3 : 269.Bd -literal -offset indent 270mdconfig -du md3 271.Ed 272.Pp 273Show detailed information on current memory disks: 274.Bd -literal -offset indent 275mdconfig -lv 276.Ed 277.Pp 278Resize the 279.Dq Li md3 280memory disk to 2 gigabytes: 281.Bd -literal -offset indent 282mdconfig -rs 2g -u md3 283.Ed 284.Pp 285Create a 1 gigabyte swap backed disk, initialize an 286.Xr ffs 7 287file system on it, and mount it on 288.Pa /tmp : 289.Bd -literal -offset indent 290mdconfig -s 1g -u md10 291newfs -U /dev/md10 292mount /dev/md10 /tmp 293chmod 1777 /tmp 294.Ed 295.Pp 296Create a memory disk out of an ISO 9660 CD image file, 297using the first available 298.Xr md 4 299device, and then mount it: 300.Bd -literal -offset indent 301mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 302.Ed 303.Pp 304Create a file-backed device from a hard disk image that begins 305with 512K of raw header information. 306.Xr gnop 8 307is used to skip over the header information, positioning 308.Pa md1.nop 309to the start of the filesystem in the image. 310.Bd -literal -offset indent 311mdconfig -u md1 -f diskimage.img 312gnop create -o 512K md1 313mount /dev/md1.nop /mnt 314.Ed 315.Sh SEE ALSO 316.Xr open 2 , 317.Xr md 4 , 318.Xr ffs 7 , 319.Xr gpart 8 , 320.Xr mdmfs 8 , 321.Xr malloc 9 322.Sh HISTORY 323The 324.Nm 325utility first appeared in 326.Fx 5.0 327as a cleaner replacement for the 328.Xr vn 4 329and 330.Xr vnconfig 8 331combo. 332.Sh AUTHORS 333The 334.Nm 335utility was written by 336.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org . 337