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 3, 2012 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 u Ar unit 76.Nm 77.Ar file 78.Sh DESCRIPTION 79The 80.Nm 81utility configures and enables 82.Xr md 4 83devices. 84.Pp 85Options indicate an action to be performed: 86.Bl -tag -width indent 87.It Fl a 88Attach a memory disk. 89This will configure and attach a memory disk with the 90parameters specified and attach it to the system. 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 a 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.El 122.It Fl f Ar file 123Filename to use for the vnode type memory disk. 124The 125.Fl a 126and 127.Fl t Ar vnode 128options are implied if not specified. 129.It Fl l 130List configured devices. 131If given with 132.Fl u , 133display details about that particular device. 134If the 135.Fl v 136option is specified, show all details. 137.It Fl n 138When printing 139.Xr md 4 140device names, print only the unit number without the 141.Xr md 4 142prefix. 143.It Fl s Ar size 144Size of the memory disk. 145.Ar Size 146is the number of 512 byte sectors unless suffixed with a 147.Cm b , k , m , g , 148or 149.Cm t 150which 151denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively. 152The 153.Fl a 154and 155.Fl t Ar swap 156options are implied if not specified. 157.It Fl S Ar sectorsize 158Sectorsize to use for the memory disk, in bytes. 159.It Fl x Ar sectors/track 160See the description of the 161.Fl y 162option below. 163.It Fl y Ar heads/cylinder 164For 165.Cm malloc 166or 167.Cm vnode 168backed devices, the 169.Fl x 170and 171.Fl y 172options can be used to specify a synthetic geometry. 173This is useful for constructing bootable images for later download to 174other devices. 175.It Fl o Oo Cm no Oc Ns Ar option 176Set or reset options. 177.Bl -tag -width indent 178.It Oo Cm no Oc Ns Cm async 179For 180.Cm vnode 181backed devices: avoid 182.Dv IO_SYNC 183for increased performance but 184at the risk of deadlocking the entire kernel. 185.It Oo Cm no Oc Ns Cm reserve 186Allocate and reserve all needed storage from the start, rather than as needed. 187.It Oo Cm no Oc Ns Cm cluster 188Enable clustering on this disk. 189.It Oo Cm no Oc Ns Cm compress 190Enable/disable compression features to reduce memory usage. 191.It Oo Cm no Oc Ns Cm force 192Disable/enable extra sanity checks to prevent the user from doing something 193that might adversely affect the system. 194.It Oo Cm no Oc Ns Cm readonly 195Enable/disable readonly mode. 196.El 197.It Fl u Ar unit 198Request a specific unit number for the 199.Xr md 4 200device instead of automatic allocation. 201.El 202.Pp 203The last form, 204.Nm 205.Ar file , 206is provided for convenience as an abbreviation of 207.Nm 208.Fl a 209.Fl t Ar vnode 210.Fl f Ar file . 211.Sh EXAMPLES 212Create a 4 megabyte 213.Xr malloc 9 214backed memory disk. 215The name of the allocated unit will be printed on stdout, such as 216.Dq Li md3 : 217.Pp 218.Dl mdconfig -a -t malloc -s 4m 219.Pp 220Create a disk named 221.Pa /dev/md4 222with 223.Pa /tmp/boot.flp 224as backing storage: 225.Pp 226.Dl mdconfig -a -t vnode -f /tmp/boot.flp -u 4 227.Pp 228Detach and free all resources used by 229.Pa /dev/md4 : 230.Pp 231.Dl mdconfig -d -u 4 232.Pp 233Create a 128MByte swap backed disk, initialize an 234.Xr ffs 7 235file system on it, and mount it on 236.Pa /tmp : 237.Bd -literal -offset indent 238mdconfig -a -t swap -s 128M -u 10 239newfs -U /dev/md10 240mount /dev/md10 /tmp 241chmod 1777 /tmp 242.Ed 243.Pp 244Create a 5MB file-backed disk 245.Po Fl a 246and 247.Fl t Ar vnode 248are implied 249.Pc : 250.Bd -literal -offset indent 251dd if=/dev/zero of=somebackingfile bs=1k count=5k 252mdconfig -f somebackingfile -u 0 253bsdlabel -w md0 auto 254newfs md0c 255mount /dev/md0c /mnt 256.Ed 257.Pp 258Create an 259.Xr md 4 260device out of an ISO 9660 CD image file 261.Po Fl a 262and 263.Fl t Ar vnode 264are implied 265.Pc , using the first available 266.Xr md 4 267device, and then mount the new memory disk: 268.Bd -literal -offset indent 269mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt 270.Pp 271.Ed 272Create a file-backed device from a hard disk image that begins 273with 512K of raw header information. 274.Xr gnop 8 275is used to skip over the header information, positioning 276.Pa md1.nop 277to the start of the filesystem in the image. 278.Bd -literal -offset indent 279mdconfig -f diskimage.img -u 1 280gnop create -o 512K md1 281mount /dev/md1.nop /mnt 282.Ed 283.Sh SEE ALSO 284.Xr md 4 , 285.Xr ffs 7 , 286.Xr bsdlabel 8 , 287.Xr fdisk 8 , 288.Xr mdmfs 8 , 289.Xr malloc 9 290.Sh HISTORY 291The 292.Nm 293utility first appeared in 294.Fx 5.0 295as a cleaner replacement for the 296.Xr vn 4 297and 298.Xr vnconfig 8 299combo. 300.Sh AUTHORS 301The 302.Nm 303utility was written by 304.An Poul-Henning Kamp 305.Aq phk@FreeBSD.org . 306