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 6, 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 , 163or 164.Cm t 165which 166denotes byte, kilobyte, megabyte, gigabyte and terabyte 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.El 219.It Fl u Ar unit 220Request a specific unit number or device name for the 221.Xr md 4 222device instead of automatic allocation. 223If a device name is specified, it must be start with 224.Dq md 225followed by the unit number. 226.El 227.Pp 228The last form, 229.Nm 230.Ar file , 231is provided for convenience as an abbreviation of 232.Nm 233.Fl a 234.Fl t Ar vnode 235.Fl f Ar file . 236.Sh EXAMPLES 237Create a disk with 238.Pa /tmp/boot.flp 239as backing storage. 240The name of the allocated unit will be printed on stdout, such as 241.Dq Li md0 : 242.Bd -literal -offset indent 243mdconfig /tmp/boot.flp 244.Ed 245.Pp 246Create a 1 gigabyte swap backed memory disk named 247.Dq Li md3 : 248.Bd -literal -offset indent 249mdconfig -s 1g -u md3 250.Ed 251.Pp 252Detach and free all resources used by 253.Pa /dev/md3 : 254.Bd -literal -offset indent 255mdconfig -du md3 256.Ed 257.Pp 258Show detailed information on current memory disks: 259.Bd -literal -offset indent 260mdconfig -lv 261.Ed 262.Pp 263Resize the 264.Dq Li md3 265memory disk to 2 gigabytes: 266.Bd -literal -offset indent 267mdconfig -rs 2g -u md3 268.Ed 269.Pp 270Create a 1 gigabyte swap backed disk, initialize an 271.Xr ffs 7 272file system on it, and mount it on 273.Pa /tmp : 274.Bd -literal -offset indent 275mdconfig -s 1g -u md10 276newfs -U /dev/md10 277mount /dev/md10 /tmp 278chmod 1777 /tmp 279.Ed 280.Pp 281Create a memory disk out of an ISO 9660 CD image file, 282using the first available 283.Xr md 4 284device, and then mount it: 285.Bd -literal -offset indent 286mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 287.Ed 288.Pp 289Create a file-backed device from a hard disk image that begins 290with 512K of raw header information. 291.Xr gnop 8 292is used to skip over the header information, positioning 293.Pa md1.nop 294to the start of the filesystem in the image. 295.Bd -literal -offset indent 296mdconfig -u md1 -f diskimage.img 297gnop create -o 512K md1 298mount /dev/md1.nop /mnt 299.Ed 300.Sh SEE ALSO 301.Xr md 4 , 302.Xr ffs 7 , 303.Xr gpart 8 , 304.Xr mdmfs 8 , 305.Xr malloc 9 306.Sh HISTORY 307The 308.Nm 309utility first appeared in 310.Fx 5.0 311as a cleaner replacement for the 312.Xr vn 4 313and 314.Xr vnconfig 8 315combo. 316.Sh AUTHORS 317The 318.Nm 319utility was written by 320.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org . 321