1.\" Copyright (c) 2013 Marcel Moolenaar 2.\" Copyright (c) 2013 Craig Rodrigues 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.\" 29.Dd October 17, 2013 30.Dt MOUNT.CONF 5 31.Os 32.Sh NAME 33.Nm mount.conf 34.Nd root file system mount configuration file 35.Sh SYNOPSIS 36.Pa /.mount.conf 37.Sh DESCRIPTION 38During the bootup process, the 39.Fx 40kernel will try to mount the root file system 41using the logic in the 42.Fn vfs_mountroot 43function in 44.Pa src/sys/kern/vfs_mountroot.c . 45The root mount logic can be described as follows: 46.Bl -enum 47.It 48The kernel will synthesize in memory a config file 49with default directives for mounting 50the root file system. 51The logic for this is in 52.Fn vfs_mountroot_conf0 . 53.It 54The kernel will first mount 55.Xr devfs 5 56as the root file system. 57.It 58Next, the kernel will parse the in-memory config file created in step 1 59and try to mount the actual root file system. 60See 61.Sx FILE FORMAT 62for the format of the config file. 63.It 64When the actual root file system is mounted, 65.Xr devfs 5 66will be re-mounted on the 67.Pa /dev 68directory. 69.It 70If a 71.Pa /.mount.conf 72file does not exist in the root file system which was 73just mounted, the root mount logic stops here. 74.It 75If a 76.Pa /.mount.conf 77file exists in the root file system which was just mounted, 78this file will be parsed, and the kernel will use this new config 79file to try to re-mount the root file system. 80See 81.Sx FILE FORMAT 82for the format of the config file. 83.It 84If the new root file system has a 85.Pa /.mount 86directory, the old root file system will be re-mounted 87on 88.Pa /.mount . 89.It 90The root mount logic will go back to step 4. 91.El 92.Pp 93The root mount logic is recursive, and step 8 will 94be repeated as long as each new root file system 95which is mounted has a 96.Pa /.mount.conf 97file. 98.Sh FILE FORMAT 99The kernel parses each line in 100.Pa .mount.conf 101and then tries to perform the action specified on that line as soon as it is parsed. 102.Bl -tag -width "XXXXXXXXXX" 103.It Ic # 104A line beginning with a # is a comment and is ignored. 105.It Ic {FS}:{MOUNTPOINT} {OPTIONS} 106The kernel will try to mount this in an 107operation equivalent to: 108.Bd -literal -offset indent 109mount -t {FS} -o {OPTIONS} {MOUNTPOINT} / 110.Ed 111.Pp 112If this is successfully mounted, 113further lines in 114.Pa .mount.conf 115are ignored. 116If all lines in 117.Pa .mount.conf 118have been processed and no root file system has been successfully 119mounted, then the action specified by 120.Ic .onfail 121is performed. 122.It Ic .ask 123When the kernel processes this line, a 124.Li mountroot> 125command-line prompt is displayed. 126At this prompt, the operator can enter the root mount. 127.It Ic .md Ar file 128Create a memory backed 129.Xr md 4 130virtual disk, using 131.Ar file 132as the backing store. 133.It Ic .onfail Ar [panic|reboot|retry|continue] 134If after parsing all the lines in 135.Pa .mount.conf 136the kernel is unable to mount a root file system, 137the 138.Ic .onfail 139directive tells the kernel what action to perform. 140.It Ic .timeout Ar N 141Before trying to mount a root file system, 142if the root mount device does not exist, wait at most 143.Ar N 144seconds for the device to appear before trying to mount it. 145If 146.Ic .timeout 147is not specified, the default timeout is 3 seconds. 148.El 149.Sh EXAMPLES 150The following example 151.Pa .mount.conf 152will direct the kernel to try mounting the root file system 153first as an ISO CD9660 file system on 154.Pa /dev/cd0 , 155then if that does not work, as an ISO CD9660 file system on 156.Pa /dev/cd1 , 157and then if that does not work, as a UFS file system on 158.Pa /dev/ada0s1a . 159If that does not work, a 160.Li mountroot> 161command-line prompt will be displayed where the operator 162can manually enter the root file system to mount. 163Finally if that does not work, the kernel will panic. 164.Bd -literal -offset indent 165.Li .onfail panic 166.Li .timeout 3 167cd9660:/dev/cd0 ro 168.Li .timeout 0 169cd9660:/dev/cd1 ro 170.Li .timeout 3 171ufs:/dev/ada0s1a 172.Li .ask 173.Ed 174.Pp 175The following example 176.Pa .mount.conf 177will direct the kernel to create a 178.Xr md 4 179memory disk attached to the file 180.Pa /data/OS-1.0.iso 181and then mount the ISO CD9660 file system 182on the md device which was just created. 183The last line is a comment which is ignored. 184.Bd -literal -offset indent 185.Li .timeout 3 186.Li .md /data/OS-1.0.iso 187.Li cd9600:/dev/md# ro 188.Li # Can also use cd9660:/dev/md0 ro 189.Ed 190.Pp 191The following example 192.Pa .mount.conf 193will direct the kernel to create a 194.Xr md 4 195memory disk attached to the file 196.Pa /data/base.ufs.uzip 197and then mount the UFS file system 198on the md uzip device which was just created 199by the 200.Xr geom_uzip 4 201driver. 202.Bd -literal -offset indent 203.Li .md /data/base.ufs.uzip 204.Li ufs:/dev/md#.uzip ro 205.Li # Can also use ufs:/dev/md0.uzip ro 206.Ed 207.Pp 208The following example 209.Pa .mount.conf 210will direct the kernel to do a unionfs 211mount on a directory 212.Pa /jail/freebsd-8-stable 213which has a 214.Xr chroot 2 215environment. 216.Bd -literal -offset indent 217.Li .timeout 3 218.Li unionfs:/jail/freebsd-8-stable 219.Ed 220.Sh NOTES 221For each root file system which is mounted, a 222.Pa /dev 223directory 224.Em must 225exist so that the root mount logic can properly re-mount 226.Xr devfs 5 . 227If this directory does not exist, the system 228may hang during the bootup process. 229.Sh SEE ALSO 230.Xr nmount 2 , 231.Xr md 4 , 232.Xr boot.config 5 , 233.Xr fstab 5 , 234.Xr boot 8 , 235.Xr loader 8 , 236.Xr mount 8 237.Sh HISTORY 238The 239.Nm 240file first appeared in 241.Fx 9.0 . 242.Sh AUTHORS 243.An -nosplit 244The root mount logic in the 245.Fx 246kernel which parses 247.Pa /.mount.conf 248was written by 249.An Marcel Moolenaar Aq Mt marcel@FreeBSD.org . 250This man page was written by 251.An Craig Rodrigues Aq Mt rodrigc@FreeBSD.org . 252