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 October 10, 2015 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.Nm 59.Fl d 60.Fl u Ar unit 61.Op Fl o Oo Cm no Oc Ns Ar force 62.Nm 63.Fl r 64.Fl u Ar unit 65.Fl s Ar size 66.Op Fl o Oo Cm no Oc Ns Ar force 67.Nm 68.Fl l 69.Op Fl n 70.Op Fl v 71.Op Fl f Ar file 72.Op Fl u Ar unit 73.Nm 74.Ar file 75.Sh DESCRIPTION 76The 77.Nm 78utility creates and controls 79.Xr md 4 80devices. 81.Pp 82Options indicate an action to be performed: 83.Bl -tag -width indent 84.It Fl a 85Attach a memory disk. 86This will configure and attach a memory disk with the 87parameters specified and attach it to the system. 88If the 89.Fl u Ar unit 90option is not provided, the newly created device name will be printed on stdout. 91.It Fl d 92Detach a memory disk from the system and release all resources. 93.It Fl r 94Resize a memory disk. 95.It Fl t Ar type 96Select the type of the memory disk. 97.Bl -tag -width "malloc" 98.It Cm malloc 99Storage for this type of memory disk is allocated with 100.Xr malloc 9 . 101This limits the size to the malloc bucket limit in the kernel. 102If the 103.Fl o Cm reserve 104option is not set, creating and filling a large 105malloc-backed memory disk is a very easy way to 106panic the system. 107.It Cm vnode 108A file specified with 109.Fl f Ar file 110becomes the backing store for this memory disk. 111.It Cm swap 112Storage for this type of memory disk is allocated from buffer 113memory. 114Pages get pushed out to swap when the system is under memory 115pressure, otherwise they stay in the operating memory. 116Using 117.Cm swap 118backing is generally preferred instead of using 119.Cm malloc 120backing. 121.It Cm null 122Bitsink; all writes do nothing, all reads return zeroes. 123.El 124.It Fl f Ar file 125Filename to use for the vnode type memory disk. 126The 127.Fl a 128and 129.Fl t Ar vnode 130options are implied if not specified. 131.It Fl l 132List configured devices. 133If given with 134.Fl u , 135display details about that particular device. 136If given with 137.Fl f Ar file , 138display 139.Xr md 4 140device names of which 141.Ar file 142is used as the backing store. 143If both of 144.Fl u 145and 146.Fl f 147options are specified, 148display devices which match the two conditions. 149If the 150.Fl v 151option is specified, show all details. 152.It Fl n 153When printing 154.Xr md 4 155device names, print only the unit number without the 156.Xr md 4 157prefix. 158.It Fl s Ar size 159Size of the memory disk. 160.Ar Size 161is the number of 512 byte sectors unless suffixed with a 162.Cm b , k , m , g , t , 163or 164.Cm p 165which 166denotes byte, kilobyte, megabyte, gigabyte, terabyte and petabyte respectively. 167When used without the 168.Fl r 169option, the 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. 211This can be used with the 212.Fl d 213flag to forcibly destroy an 214.Xr md 4 215disk that is still in use. 216.It Oo Cm no Oc Ns Cm readonly 217Enable/disable readonly mode. 218.It Oo Cm no Oc Ns Cm verify 219For 220.Cm vnode 221backed devices: enable/disable requesting verification of the 222file used for backing store. 223The type of verification depends on which security features are available. 224One example of verification is testing file integrity with 225checksums or cryptographic signatures. 226.El 227.It Fl u Ar unit 228Request a specific unit number or device name for the 229.Xr md 4 230device instead of automatic allocation. 231If a device name is specified, it must be start with 232.Dq md 233followed by the unit number. 234.El 235.Pp 236The last form, 237.Nm 238.Ar file , 239is provided for convenience as an abbreviation of 240.Nm 241.Fl a 242.Fl t Ar vnode 243.Fl f Ar file . 244.Sh EXAMPLES 245Create a disk with 246.Pa /tmp/boot.flp 247as backing storage. 248The name of the allocated unit will be printed on stdout, such as 249.Dq Li md0 : 250.Bd -literal -offset indent 251mdconfig /tmp/boot.flp 252.Ed 253.Pp 254Create a 1 gigabyte swap backed memory disk named 255.Dq Li md3 : 256.Bd -literal -offset indent 257mdconfig -s 1g -u md3 258.Ed 259.Pp 260Detach and free all resources used by 261.Pa /dev/md3 : 262.Bd -literal -offset indent 263mdconfig -du md3 264.Ed 265.Pp 266Show detailed information on current memory disks: 267.Bd -literal -offset indent 268mdconfig -lv 269.Ed 270.Pp 271Resize the 272.Dq Li md3 273memory disk to 2 gigabytes: 274.Bd -literal -offset indent 275mdconfig -rs 2g -u md3 276.Ed 277.Pp 278Create a 1 gigabyte swap backed disk, initialize an 279.Xr ffs 7 280file system on it, and mount it on 281.Pa /tmp : 282.Bd -literal -offset indent 283mdconfig -s 1g -u md10 284newfs -U /dev/md10 285mount /dev/md10 /tmp 286chmod 1777 /tmp 287.Ed 288.Pp 289Create a memory disk out of an ISO 9660 CD image file, 290using the first available 291.Xr md 4 292device, and then mount it: 293.Bd -literal -offset indent 294mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 295.Ed 296.Pp 297Create a file-backed device from a hard disk image that begins 298with 512K of raw header information. 299.Xr gnop 8 300is used to skip over the header information, positioning 301.Pa md1.nop 302to the start of the filesystem in the image. 303.Bd -literal -offset indent 304mdconfig -u md1 -f diskimage.img 305gnop create -o 512K md1 306mount /dev/md1.nop /mnt 307.Ed 308.Sh SEE ALSO 309.Xr open 2 , 310.Xr md 4 , 311.Xr ffs 7 , 312.Xr gpart 8 , 313.Xr mdmfs 8 , 314.Xr malloc 9 315.Sh HISTORY 316The 317.Nm 318utility first appeared in 319.Fx 5.0 320as a cleaner replacement for the 321.Xr vn 4 322and 323.Xr vnconfig 8 324combo. 325.Sh AUTHORS 326The 327.Nm 328utility was written by 329.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org . 330