Provided by: dracut_027-1_all 
NAME
dracut.cmdline - dracut kernel command line options
DESCRIPTION
The root device used by the kernel is specified in the boot configuration file on the
kernel command line, as always.
The traditional root=/dev/sda1 style device specification is allowed, but not encouraged.
The root device should better be identified by LABEL or UUID. If a label is used, as in
root=LABEL=<label_of_root> the initramfs will search all available devices for a
filesystem with the appropriate label, and mount that device as the root filesystem.
root=UUID=<uuidnumber> will mount the partition with that UUID as the root filesystem.
In the following all kernel command line parameters, which are processed by dracut, are
described.
"rd.*" parameters mentioned without "=" are boolean parameters. They can be turned on/off
by setting them to {0|1}. If the assignment with "=" is missing "=1" is implied. For
example rd.info can be turned off with rd.info=0 or turned on with rd.info=1 or rd.info.
The last value in the kernel command line is the value, which is honored.
Standard
init=<path to real init>
specify the path to the init programm to be started after the initramfs has finished
root=<path to blockdevice>
specify the block device to use as the root filesystem.
E.g.:
root=/dev/sda1
root=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
root=/dev/disk/by-label/Root
root=LABEL=Root
root=/dev/disk/by-uuid/3f5ad593-4546-4a94-a374-bcfb68aa11f7
root=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
root=PARTUUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
rootfstype=<filesystem type>
"auto" if not specified, e.g.:
rootfstype=ext3
rootflags=<mount options>
specify additional mount options for the root filesystem. If not set, /etc/fstab of
the real root will be parsed for special mount options and mounted accordingly.
ro
force mounting / and /usr (if it is a separate device) read-only. If none of ro and rw
is present, both are mounted according to /etc/fstab.
rw
force mounting / and /usr (if it is a separate device) read-write. See also ro option.
rd.auto rd.auto=1
enable autoassembly of special devices like cryptoLUKS, dmraid, mdraid or lvm. Default
is off as of dracut version >= 024.
rd.fstab=0
do not honor special mount options for the root filesystem found in /etc/fstab of the
real root.
resume=<path to resume partition>
resume from a swap partition
E.g.:
resume=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
resume=/dev/disk/by-uuid/3f5ad593-4546-4a94-a374-bcfb68aa11f7
resume=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
rd.skipfsck
skip fsck for rootfs and /usr. If you’re mounting /usr read-only and the init system
performs fsck before remount, you might want to use this option to avoid duplication.
Misc
rd.driver.blacklist=<drivername>[,<drivername>,...]
do not load kernel module <drivername>. This parameter can be specified multiple
times.
rd.driver.pre=<drivername>[,<drivername>,...]
force loading kernel module <drivername>. This parameter can be specified multiple
times.
rd.driver.post=<drivername>[,<drivername>,...]
force loading kernel module <drivername> after all automatic loading modules have been
loaded. This parameter can be specified multiple times.
rd.retry=<seconds>
specify how long dracut should wait for devices to appear. The default is 30 seconds.
After 2/3 of the time, degraded raids are force started. If you have hardware, which
takes a very long time to announce its drives, you might want to extend this value.
rd.noverifyssl
accept self-signed certificates for ssl downloads.
rd.ctty=<terminal device>**
specify the controlling terminal for the console. This is useful, if you have multiple
"console=" arguments.
Debug
If you are dropped to an emergency shell, the file /run/initramfs/sosreport.txt is
created, which can be safed to a (to be mounted by hand) partition (usually /boot) or a
USB stick. Additional debugging info can be produced by adding rd.debug to the kernel
command line. /run/initramfs/sosreport.txt contains all logs and the output of some tools.
It should be attached to any report about dracut problems.
rd.info
print informational output though "quiet" is set
rd.shell
allow dropping to a shell, if root mounting fails
rd.debug
set -x for the dracut shell. If systemd is active in the initramfs, all output is
logged to the systemd journal, which you can inspect with "journalctl -ab". If systemd
is not active, the logs are written to dmesg and /run/initramfs/init.log. If "quiet"
is set, it also logs to the console.
rd.memdebug=[0-3]
Print memory usage info at various points, set the verbose level from 0 to 3 Higher
level means more debugging output: 0 - no output 1 - partial /proc/meminfo 2 -
/proc/meminfo 3 - /proc/meminfo + /proc/slabinfo
rd.break
drop to a shell at the end
rd.break={cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup}
drop to a shell on defined breakpoint
rd.udev.info
set udev to loglevel info
rd.udev.debug
set udev to loglevel debug
I18N
vconsole.keymap=<keymap base file name>
keyboard translation table loaded by loadkeys; taken from keymaps directory; will be
written as KEYMAP to /etc/vconsole.conf in the initramfs, e.g.:
vconsole.keymap=de-latin1-nodeadkeys
vconsole.keymap.ext=<list of keymap base file names>
list of extra keymaps to bo loaded (sep. by space); will be written as EXT_KEYMAP to
/etc/vconsole.conf in the initramfs
vconsole.unicode[={0|1}]
boolean, indicating UTF-8 mode; will be written as UNICODE to /etc/vconsole.conf in
the initramfs
vconsole.font=<font base file name>
console font; taken from consolefonts directory; will be written as FONT to
/etc/vconsole.conf in the initramfs; e.g.:
vconsole.font=LatArCyrHeb-16
vconsole.font.map=<console map base file name>
see description of -m parameter in setfont manual; taken from consoletrans directory;
will be written as FONT_MAP to /etc/vconsole.conf in the initramfs
vconsole.font.unimap=<unicode table base file name>
see description of -u parameter in setfont manual; taken from unimaps directory; will
be written as FONT_UNIMAP to /etc/vconsole.conf in the initramfs
locale.LANG=<locale>
taken from the environment; if no UNICODE is defined we set its value in basis of LANG
value (whether it ends with ".utf8" (or similar) or not); will be written as LANG to
/etc/locale.conf in the initramfs; e.g.:
locale.LANG=pl_PL.utf8
locale.LC_ALL=<locale>
taken from the environment; will be written as LC_ALL to /etc/locale.conf in the
initramfs
LVM
rd.lvm=0
disable LVM detection
rd.lvm.vg=<volume group name>
only activate the volume groups with the given name. rd.lvm.vg can be specified
multiple times on the kernel command line.
rd.lvm.lv=<logical volume name>
only activate the logical volumes with the given name. rd.lvm.lv can be specified
multiple times on the kernel command line.
rd.lvm.conf=0
remove any /etc/lvm/lvm.conf, which may exist in the initramfs
crypto LUKS
rd.luks=0
disable crypto LUKS detection
rd.luks.uuid=<luks uuid>
only activate the LUKS partitions with the given UUID. Any "luks-" of the LUKS UUID is
removed before comparing to <luks uuid>. The comparisons also matches, if <luks uuid>
is only the beginning of the LUKS UUID, so you don’t have to specify the full UUID.
This parameter can be specified multiple times.
rd.luks.allow-discards=<luks uuid>
Allow using of discards (TRIM) requests for LUKS partitions with the given UUID. Any
"luks-" of the LUKS UUID is removed before comparing to <luks uuid>. The comparisons
also matches, if <luks uuid> is only the beginning of the LUKS UUID, so you don’t have
to specify the full UUID. This parameter can be specified multiple times.
rd.luks.allow-discards
Allow using of discards (TRIM) requests on all LUKS partitions.
rd.luks.crypttab=0
do not check, if LUKS partition is in /etc/crypttab
crypto LUKS - key on removable device support
rd.luks.key=<keypath>:<keydev>:<luksdev>
keypath is a path to key file to look for. It’s REQUIRED. When keypath ends with .gpg
it’s considered to be key encrypted symmetrically with GPG. You will be prompted for
password on boot. GPG support comes with crypt-gpg module which needs to be added
explicitly.
keydev is a device on which key file resides. It might be kernel name of devices
(should start with "/dev/"), UUID (prefixed with "UUID=") or label (prefix with
"LABEL="). You don’t have to specify full UUID. Just its beginning will suffice, even
if its ambiguous. All matching devices will be probed. This parameter is recommended,
but not required. If not present, all block devices will be probed, which may
significantly increase boot time.
If luksdev is given, the specified key will only be applied for that LUKS device.
Possible values are the same as for keydev. Unless you have several LUKS devices, you
don’t have to specify this parameter. The simplest usage is:
rd.luks.key=/foo/bar.key
As you see, you can skip colons in such a case.
Note
dracut pipes key to cryptsetup with -d - argument, therefore you need to pipe to
crypsetup luksFormat with -d -, too!
Here follows example for key encrypted with GPG:
gpg --quiet --decrypt rootkey.gpg \
| cryptsetup -d - -v \
--cipher serpent-cbc-essiv:sha256 \
--key-size 256 luksFormat /dev/sda3
If you use plain keys, just add path to -d option:
cryptsetup -d rootkey.key -v \
--cipher serpent-cbc-essiv:sha256 \
--key-size 256 luksFormat /dev/sda3
MD RAID
rd.md=0
disable MD RAID detection
rd.md.imsm=0
disable MD RAID for imsm/isw raids, use DM RAID instead
rd.md.ddf=0
disable MD RAID for SNIA ddf raids, use DM RAID instead
rd.md.conf=0
ignore mdadm.conf included in initramfs
rd.md.waitclean=1
wait for any resync, recovery, or reshape activity to finish before continuing
rd.md.uuid=<md raid uuid>
only activate the raid sets with the given UUID. This parameter can be specified
multiple times.
DM RAID
rd.dm=0
disable DM RAID detection
rd.dm.uuid=<dm raid uuid>
only activate the raid sets with the given UUID. This parameter can be specified
multiple times.
FIPS
rd.fips
enable FIPS
boot=<boot device>
specify the device, where /boot is located. e.g.
boot=/dev/sda1
boot=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
boot=UUID=<uuid>
boot=LABEL=<label>
rd.fips.skipkernel
skip checksum check of the kernel image. Useful, if the kernel image is not in a
separate boot partition.
Network
ip={dhcp|on|any|dhcp6|auto6|ibft}
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.
auto6
IPv6 autoconfiguration
dhcp6
IPv6 DHCP
ibft
iBFT autoconfiguration
ip=<interface>:_{dhcp|on|any|dhcp6|auto6}_[:[<mtu>][:_<macaddr>_]]
This parameter can be specified multiple times.
dhcp|on|any|dhcp6
get ip from dhcp server on a specific interface
auto6
do IPv6 autoconfiguration
<macaddr>
optionally set <macaddr> on the <interface>. This cannot be used in conjunction
with the ifname argument for the same <interface>.
Important
It is recommended to either bind <interface> to a MAC with the ifname argument. Or use
biosdevname to name your interfaces, which will then have names according to their
hardware location.
em<port>
for embedded NICs
p<slot>#<port>_<virtual instance>
for cards in PCI slots
ip=<client-IP>:_<server-IP>_:_<gateway-IP>_:_<netmask>_:_<client_hostname>_:_<interface>_:_{none|off|dhcp|on|any|dhcp6|auto6|ibft}_[:[<mtu>][:_<macaddr>_]]
explicit network configuration. If you want do define a IPv6 address, put it in
brackets (e.g. [2001:DB8::1]). This parameter can be specified multiple times.
<macaddr>
optionally set <macaddr> on the <interface>. This cannot be used in conjunction
with the ifname argument for the same <interface>.
Important
It is recommended to either bind <interface> to a MAC with the ifname argument. Or use
biosdevname to name your interfaces, which will then have names according to their
hardware location.
em<port>
for embedded NICs
p<slot>#<port>_<virtual instance>
for cards in PCI slots
ifname=<interface>:_<MAC>_
Assign network device name <interface> (ie "bootnet") to the NIC with MAC <MAC>.
Important
Do not use the default kernel naming scheme for the interface name, as it can
conflict with the kernel names. So, don’t use "eth[0-9]+" for the interface name.
Better name it "bootnet" or "bluesocket".
bootdev=<interface>
specify network interface to use routing and netroot information from. Required if
multiple ip= lines are used.
nameserver=<IP> [nameserver=<IP> ...]
specify nameserver(s) to use
biosdevname=0
boolean, turn off biosdevname network interface renaming
rd.neednet=1
boolean, bring up network even without netroot set
vlan=<vlanname>:_<phydevice>_
Setup vlan device named <vlanname> on <phydeivce>. We support the four styles of vlan
names: VLAN_PLUS_VID (vlan0005), VLAN_PLUS_VID_NO_PAD (vlan5), DEV_PLUS_VID
(eth0.0005), DEV_PLUS_VID_NO_PAD (eth0.5)
bond=<bondname>[:_<bondslaves>_:[:_<options>_]]
Setup bonding device <bondname> on top of <bondslaves>. <bondslaves> is a
comma-separated list of physical (ethernet) interfaces. <options> is a comma-separated
list on bonding options (modinfo bonding for details) in format compatible with
initscripts. If <options> includes multi-valued arp_ip_target option, then its values
should be separated by semicolon. Bond without parameters assumes
bond=bond0:eth0,eth1:mode=balance-rr
team =<teammaster>:_<teamslaves>_
Setup team device <teammaster> on top of <teamslaves>. <teamslaves> is a
comma-separated list of physical (ethernet) interfaces.
bridge=<bridgename>:_<ethnames>_
Setup bridge <bridgename> with <ethnames>. <ethnames> is a comma-separated list of
physical (ethernet) interfaces. Bridge without parameters assumes bridge=br0:eth0
NFS
root=<root-dir>[:_<nfs-options>_]
mount nfs share from <server-ip>:/<root-dir>, if no server-ip is given, use dhcp
next_server. if server-ip is an IPv6 address it has to be put in brackets, e.g.
[2001:DB8::1]. NFS options can be appended with the prefix ":" or "," and are
seperated by ",".
root=nfs:[<server-ip>:]<root-dir>[:_<nfs-options>_],
root=nfs4:[<server-ip>:]<root-dir>[:_<nfs-options>_], root={dhcp|dhcp6}
root=dhcp alone directs initrd to look at the DHCP root-path where NFS options can be
specified.
root-path=<server-ip>:<root-dir>[,<nfs-options>]
root-path=nfs:<server-ip>:<root-dir>[,<nfs-options>]
root-path=nfs4:<server-ip>:<root-dir>[,<nfs-options>]
root=/dev/nfs nfsroot=<root-dir>[:_<nfs-options>_]
Deprecated! kernel Documentation_/filesystems/nfsroot.txt_ defines this method. This
is supported by dracut, but not recommended.
rd.nfs.domain=<NFSv4 domain name>
Set the NFSv4 domain name. Will overwrite the settings in /etc/idmap.conf.
CIFS
root=cifs://[<username>[:_<password>_]@]<server-ip>:_<root-dir>_
mount cifs share from <server-ip>:/<root-dir>, if no server-ip is given, use dhcp
next_server. if server-ip is an IPv6 address it has to be put in brackets, e.g.
[2001:DB8::1]. If a username or password are not specified as part of the root, then
they must be passed on the command line through cifsuser/cifspass.
Warning
Passwords specified on the kernel command line are visible for all users via the
file /proc/cmdline and via dmesg or can be sniffed on the network, when using DHCP
with DHCP root-path.
**cifsuser=<username>
Set the cifs username, if not specified as part of the root.
**cifspass=<password>
Set the cifs password, if not specified as part of the root.
Warning
Passwords specified on the kernel command line are visible for all users via the
file /proc/cmdline and via dmesg or can be sniffed on the network, when using DHCP
with DHCP root-path.
iSCSI
root=iscsi:[<username>:_<password>_[:_<reverse>_:_<password>_]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<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. 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. See rfc4173[1]. e.g.:
root=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
If servername is an IPv6 address, it has to be put in brackets. e.g.:
root=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
Warning
Passwords specified on the kernel command line are visible for all users via the
file /proc/cmdline and via dmesg or can be sniffed on the network, when using DHCP
with DHCP root-path.
root=???
netroot=iscsi:[<username>:_<password>_[:_<reverse>_:_<password>_]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<LUN>]:_<targetname>_
...
multiple netroot options allow setting up multiple iscsi disks. e.g.:
root=UUID=12424547
netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target1
If servername is an IPv6 address, it has to be put in brackets. e.g.:
netroot=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
Warning
Passwords specified on the kernel command line are visible for all users via the
file /proc/cmdline and via dmesg or can be sniffed on the network, when using DHCP
with DHCP root-path. You may want to use rd.iscsi.firmware.
root=??? rd.iscsi.initiator=<initiator> rd.iscsi.target.name=<target name>
rd.iscsi.target.ip=<target ip> rd.iscsi.target.port=<target port>
rd.iscsi.target.group=<target group> rd.iscsi.username=<username>
rd.iscsi.password=<password> rd.iscsi.in.username=<in username> rd.iscsi.in.password=<in
password>
manually specify all iscsistart parameter (see iscsistart --help)
Warning
Passwords specified on the kernel command line are visible for all users via the
file /proc/cmdline and via dmesg or can be sniffed on the network, when using DHCP
with DHCP root-path. You may want to use rd.iscsi.firmware.
root=??? netroot=iscsi rd.iscsi.firmware=1
will read the iscsi parameter from the BIOS firmware
rd.iscsi.param=<param>
<param> will be passed as "--param <param>" to iscsistart. This parameter can be
specified multiple times. e.g.:
"netroot=iscsi rd.iscsi.firmware=1 rd.iscsi.param=node.session.timeo.replacement_timeout=30"
will result in
iscsistart -b --param node.session.timeo.replacement_timeout=30
FCoE
fcoe=<edd|interface|MAC>:_{dcb|nodcb}_
Try to connect to a FCoE SAN through the NIC specified by <interface> or <MAC> or EDD
settings. For the second argument, currently only nodcb is supported. This parameter
can be specified multiple times.
Note
letters in the MAC-address must be lowercase!
NBD
root=??? netroot=nbd:_<server>_:_<port>_[:_<fstype>_[:_<mountopts>_[:_<nbdopts>_]]]
mount nbd share from <server>
root=dhcp with dhcp
root-path=nbd:_<server>_:_<port>_[:_<fstype>_[:_<mountopts>_[:_<nbdopts>_]]]
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.
DASD
rd.dasd=....
same syntax as the kernel module parameter (s390 only)
ZFCP
rd.zfcp=<zfcp adaptor device bus ID>,<WWPN>,<FCPLUN>
rd.zfcp can be specified multiple times on the kernel command line. e.g.:
rd.zfcp=0.0.4000,0x5005076300C213e9,0x5022000000000000
rd.zfcp.conf=0
ignore zfcp.conf included in the initramfs
ZNET
rd.znet=<nettype>,<subchannels>,<options>
rd.znet can be specified multiple times on the kernel command line. e.g.:
rd.znet=qeth,0.0.0600,0.0.0601,0.0.0602,layer2=1,portname=foo
rd.znet=ctc,0.0.0600,0.0.0601,protocol=bar
Plymouth Boot Splash
plymouth.enable=0
disable the plymouth bootsplash completly.
rd.plymouth=0
disable the plymouth bootsplash only for the initramfs.
Kernel keys
masterkey=<kernel master key path name>
Set the path name of the kernel master key. e.g.:
masterkey=/etc/keys/kmk-trusted.blob
masterkeytype=<kernel master key type>
Set the type of the kernel master key. e.g.:
masterkeytype=trusted
evmkey=<EVM key path name>
Set the path name of the EVM key. e.g.:
evmkey=/etc/keys/evm-trusted.blob
ecryptfskey=<eCryptfs key path name>
Set the path name of the eCryptfs key. e.g.:
ecryptfskey=/etc/keys/ecryptfs-trusted.blob
Deprecated, renamed Options
Here is a list of options, which were used in dracut prior to version 008, and their new
replacement.
rdbreak
rd.break
rd_CCW
rd.ccw
rd_DASD_MOD
rd.dasd
rd_DASD
rd.dasd
rdinitdebug rdnetdebug
rd.debug
rd_NO_DM
rd.dm=0
rd_DM_UUID
rd.dm.uuid
rdblacklist
rd.driver.blacklist
rdinsmodpost
rd.driver.post
rdloaddriver
rd.driver.pre
rd_NO_FSTAB
rd.fstab=0
rdinfo
rd.info
check
rd.live.check
rdlivedebug
rd.live.debug
live_dir
rd.live.dir
liveimg
rd.live.image
overlay
rd.live.overlay
readonly_overlay
rd.live.overlay.readonly
reset_overlay
rd.live.overlay.reset
live_ram
rd.live.ram
rd_NO_CRYPTTAB
rd.luks.crypttab=0
rd_LUKS_KEYDEV_UUID
rd.luks.keydev.uuid
rd_LUKS_KEYPATH
rd.luks.keypath
rd_NO_LUKS
rd.luks=0
rd_LUKS_UUID
rd.luks.uuid
rd_NO_LVMCONF
rd.lvm.conf
rd_LVM_LV
rd.lvm.lv
rd_NO_LVM
rd.lvm=0
rd_LVM_SNAPSHOT
rd.lvm.snapshot
rd_LVM_SNAPSIZE
rd.lvm.snapsize
rd_LVM_VG
rd.lvm.vg
rd_NO_MDADMCONF
rd.md.conf=0
rd_NO_MDIMSM
rd.md.imsm=0
rd_NO_MD
rd.md=0
rd_MD_UUID
rd.md.uuid
rd_NFS_DOMAIN
rd.nfs.domain
iscsi_initiator
rd.iscsi.initiator
iscsi_target_name
rd.iscsi.target.name
iscsi_target_ip
rd.iscsi.target.ip
iscsi_target_port
rd.iscsi.target.port
iscsi_target_group
rd.iscsi.target.group
iscsi_username
rd.iscsi.username
iscsi_password
rd.iscsi.password
iscsi_in_username
rd.iscsi.in.username
iscsi_in_password
rd.iscsi.in.password
iscsi_firmware
rd.iscsi.firmware=0
rd_NO_PLYMOUTH
rd.plymouth=0
rd_retry
rd.retry
rdshell
rd.shell
rd_NO_SPLASH
rd.splash
rdudevdebug
rd.udev.debug
rdudevinfo
rd.udev.info
rd_NO_ZFCPCONF
rd.zfcp.conf=0
rd_ZFCP
rd.zfcp
rd_ZNET
rd.znet
KEYMAP
vconsole.keymap
KEYTABLE
vconsole.keymap
SYSFONT
vconsole.font
CONTRANS
vconsole.font.map
UNIMAP
vconsole.font.unimap
UNICODE
vconsole.unicode
EXT_KEYMAP
vconsole.keymap.ext
Configuration in the Initramfs
/etc/conf.d/
Any files found in /etc/conf.d/ will be sourced in the initramfs to set initial
values. Command line options will override these values set in the configuration
files.
/etc/cmdline
Can contain additional command line options. Deprecated, better use
/etc/cmdline.d/*.conf.
/etc/cmdline.d/*.conf
Can contain additional command line options.
AUTHOR
Harald Hoyer
SEE ALSO
dracut(8) dracut.conf(5)
NOTES
1. rfc4173
http://tools.ietf.org/html/rfc4173#section-5