dracut/dracut.8

.TH DRACUT 8 "June 2009" "Linux"
.SH NAME
switch_root \- switch to another filesystem as the root of the mount tree.
.SH SYNOPSIS
\fBdracut\fR [\fIOPTION\fR]... \fI<image>\fR  \fI<kernel-version>\fR

.SH DESCRIPTION
.B switch_root
\fBdracut\fR creates an initial image used by the kernel for
preloading the block device modules (such as IDE, SCSI or RAID)
which are needed to access the root filesystem.

.SH OPTIONS
.TP
.BR \-f ", " \-\-force
overwrite existing initramfs file.
.TP
.BR \-m ", " \-\-modules " \fILIST\fR"
specify a space-separated list of dracut modules to call 
when building the initramfs. 
Modules are located in 
.IR /usr/lib/dracut/modules.d .
.TP
.BR \-o ", " \-\-omit " \fILIST\fR"
omit a space-separated list of dracut modules.
.TP
.BR \-d ", " \-\-drivers " \fILIST\fR"
specify a space-separated list of kernel modules to include in the initramfs.
.TP
.BR \-h ", " \-\-help
display help text and exit. 
.TP
.B \-\-debug
output debug information of the build process
.TP
.BR \-v ", " \-\-verbose
verbose output during the build process
.TP
.BR \-c ", " \-\-conf " \fIFILE\fR"
specify configuration file to use.
Default: 
.IR /etc/dracut.conf
.TP
.BR \-l ", " \-\-local
local mode. Use modules from the current working
directory instead of the system-wide installed in
.IR /usr/lib/dracut/modules.d .
Useful when running dracut from a git checkout.
.TP
.BR \-H ", " \-\-hostonly
Host-Only mode: Install only what is needed for
booting the local host instead of a generic host.
.TP
.BR \-i ", " \-\-include " \fISOURCE\fR" "" " \fITARGET\fR"
include the files in the SOURCE directory into the
target directory in the final initramfs.
.TP
.BR \-I ", " \-\-install " \fILIST\fR"
install the space separated list of files into the initramfs.

.SH KERNEL COMMAND LINE
The root filesystem used by the kernel is specified in the boot configuration
file, as always. The traditional \fBroot=/dev/hda1\fR style device 
specification is allowed. If a label is used, as in \fBroot=LABEL=rootPart\fR
the initrd will search all available devices for an ext2 or ext3 filesystem
with the appropriate label, and mount that device as the root filesystem.
\fBroot=UUID=uuidnumber\fR will mount the partition with that UUID as the 
root filesystem.

.SH Standard
.TP
.B init=<path to real init>
.TP
.B root=<path to blockdevice>
specify e.g. \fI/dev/sda1\fR or
\fI/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1\fR

.SH DHCP
.TP
.B root=dhcp
get IP from dhcp server, root-path option from dhcp specifies root location

.SH NFS
.TP
.B root=[<server-ip>:]<root-dir>[:<nfs-options>]
mount nfs share from <server-ip>:/<root-dir>, if no server-ip is given,
use dhcp next_server. 
NFS options can be appended with the prefix "." or ","
.TP
.B root=dhcp root-path=<server-ip>:<root-dir>[:<nfs-options>]
root=dhcp alone directs initrd to look at the DHCP root-path where NFS 
options can be specified.
.TP
.B root=/dev/nfs nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
\fBDeprecated!\fR kernel Documentation/filesystems/nfsroot.txt defines 
this method.  
This is supported by dracut but not recommended.

.SH iSCSI
.TP
.B root=iscsi:[<servername>]:[<protocol>]:[<port>]:[<LUN>]:<targetname>
protocol defaults to "6", LUN defaults to "0".

If the "servername" field is provided by BOOTP or DHCP, then that
field is used in conjunction with other associated fields to contact
the boot server in the Boot stage (Section 7).  However, if the
"servername" field is not provided, then the "targetname" field is
then used in the Discovery Service stage in conjunction with other
associated fields.

http://tools.ietf.org/html/rfc4173

.TP
.B root=??? iscsiroot=...
.TP
.B root=??? iscsi_initiator= iscsi_target_name= iscsi_target_ip= iscsi_target_port= iscsi_target_group= iscsi_username=  iscsi_password= iscsi_in_username= iscsi_in_password=
.TP
.B root=??? iscsi_firmware

.SH NBD
.TP
.B root=nbd:<server>:<port>[:<fstype>][:<mountopts>]
mount nbd share from <server>
.TP
.B root=dhcp root-path=nbd:<server>:<port>[:<fstype>][:<mountopts>]
root=dhcp alone directs initrd to look at the DHCP root-path where NBD options can be specified.
This syntax is only usable in cases where you are directly mounting the volume as the rootfs.

.SH Network
.TP bootdev=<interface>
.B specify the network interface to boot from
.TP
.B ip=[dhcp|on|any]
get ip from dhcp server from all interfaces. If root=dhcp, loop sequentially through all interfaces (eth0, eth1, ...) and use the first with a valid DHCP root-path.
.TP
.B ip=<interface>:[dhcp|on|any]
get ip from dhcp server on a specific interface
.TP
.B ip=<client-IP-number>:<gateway-IP-number>:<netmask>:<client-hostname>:<interface>:[dhcp|on|any|]
explicit network configuration

.SH Misc
.TP
.B rdblacklist=<modulename>
TBD: do not load modulename

.SH Debug
.TP
.B rdinitdebug
set -x for the dracut shell
.TP
.B rdbreak=[pre-udev|pre-mount|mount|pre-pivot|]
drop the shell on defined breakpoint
.TP
.B rdudevinfo
set udev to loglevel info
.TP
.B rdudevdebug
set udev to loglevel debug
.TP
.B rdnetdebug
debug network scripts in dracut. Output is written to /tmp/


.SH CONFIGURATION IN INITRAMFS
.TP 
.B /conf/conf.d/
Any files found in /conf/conf.d/ will be sourced in the initramfs to 
specify special variables. 
Command line options can override values set here.

.SH AUTHORS
.nf
Andreas Thienemann <andreas@bawue.net>
Bill Nottingham <notting@redhat.com>
Dave Jones <davej@redhat.com>
David Dillow <dave@thedillows.org>
Harald Hoyer <harald@redhat.com>
Jeremy Katz <katzj@redhat.com>
Peter Jones <pjones@redhat.com>
Seewer Philippe <philippe.seewer@bfh.ch>
Victor Lowther <victor.lowther@gmail.com>
Warren Togami <wtogami@redhat.com>
.fi
.SH AVAILABILITY
The dracut command is part of the dracut package and is available from
https://sourceforge.net/apps/trac/dracut/wiki