dmsquash-live-root: Extend rd.live.overlay.readonly support

[thirdparty/dracut.git] / dracut.cmdline.7.asc

DRACUT.CMDLINE(7)
=================
:doctype: manpage
:man source:   dracut
:man manual:   dracut

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 program to be started after the initramfs has
    finished

**root=**__<path to blockdevice>__::
    specify the block device to use as the root filesystem.
+
[listing]
.Example
--
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.
+
[listing]
.Example
--
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.

**rootfallback=**__<path to blockdevice>__::
    specify the block device to use as the root filesystem, if the normal root
    cannot be found. This can only be a simple block device with a simple file
    system, for which the filesystem driver is either compiled in, or added
    manually to the initramfs. This parameter can be specified multiple times.

**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.hostonly=0**::
    removes all compiled in configuration of the host system the initramfs image
    was built on. This helps booting, if any disk layout changed, especially in
    combination with rd.auto or other parameters specifying the layout.

**rd.cmdline=ask**::
    prompts the user for additional kernel command line parameters

**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
+
[listing]
.Example
--
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.

iso-scan/filename
~~~~~~~~~~~~~~~~~

Using iso-scan/filename with a Fedora/Red Hat/CentOS Live iso should just work
by copying the original kernel cmdline parameters.

[listing]
.Example
--
menuentry 'Live Fedora 20' --class fedora --class gnu-linux --class gnu --class os {
    set isolabel=Fedora-Live-LXDE-x86_64-20-1
    set isofile="/boot/iso/Fedora-Live-LXDE-x86_64-20-1.iso"
    loopback loop $isofile
    linux (loop)/isolinux/vmlinuz0 boot=isolinux iso-scan/filename=$isofile root=live:LABEL=$isolabel ro rd.live.image quiet rhgb
    initrd (loop)/isolinux/initrd0.img
}
--

Misc
~~~~
**rd.emergency=**__[reboot|poweroff|halt]__::
    specify, what action to execute in case of a critical failure. rd.shell=0 also
    be specified.

**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 retry the initqueue to configure devices.
    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.timeout=**__<seconds>__::
    specify how long dracut should wait for devices to appear. The
    default is '0', which means 'forever'. Note that this timeout
    should be longer than rd.retry to allow for proper configuration.

**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.

[[dracutkerneldebug]]
Debug
~~~~~
If you are dropped to an emergency shell, the file 
_/run/initramfs/rdsosreport.txt_ is created, which can be saved 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/rdsosreport.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=[0-4]**::
    Print memory usage info at various points, set the verbose level from 0 to 4.
+    
    Higher level means more debugging output:
+
----
    0 - no output
    1 - partial /proc/meminfo
    2 - /proc/meminfo
    3 - /proc/meminfo + /proc/slabinfo
    4 - /proc/meminfo + /proc/slabinfo + tracekomem
        NOTE: tracekomem is a shell script utilizing kernel trace to track
              the rough total memory consumption of kernel modules during
              loading. It may override other trace configurations.
----

**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
~~~~
**rd.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.
+
[listing]
.Example
--
rd.vconsole.keymap=de-latin1-nodeadkeys
--

**rd.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

**rd.vconsole.unicode**::
    boolean, indicating UTF-8 mode; will be written as UNICODE to
    _/etc/vconsole.conf_ in the initramfs

**rd.vconsole.font=**__<font base file name>__::
    console font; taken from consolefonts directory; will be written as FONT to
    _/etc/vconsole.conf_ in the initramfs.
+
[listing]
.Example
--
rd.vconsole.font=LatArCyrHeb-16
--

**rd.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

**rd.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

**rd.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.
+
[listing]
.Example
--
rd.locale.LANG=pl_PL.utf8
--

**rd.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:
+
[listing]
.Example
--
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:

[listing]
--
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:

[listing]
--
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.

MULTIPATH
~~~~~~~~~
**rd.multipath=0**::
   disable multipath detection

FIPS
~~~~
**rd.fips**::
    enable FIPS

**boot=**__<boot device>__::
    specify the device, where /boot is located.
+
[listing]
.Example
--
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
~~~~~~~

[IMPORTANT]
=====================
It is recommended to either bind an interface to a MAC with the **ifname**
argument, or to use the systemd-udevd predictable network interface names.

Predictable network interface device names based on:

- firmware/bios-provided index numbers for on-board devices
- firmware-provided pci-express hotplug slot index number
- physical/geographical location of the hardware
- the interface's MAC address

See:
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames

Two character prefixes based on the type of interface:

en:: ethernet
wl:: wlan
ww:: wwan

Type of names:

o<index>:: on-board device index number
s<slot>[f<function>][d<dev_id>]:: hotplug slot index number
x<MAC>:: MAC address
[P<domain>]p<bus>s<slot>[f<function>][d<dev_id>]:: PCI geographical location
[P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]:: USB port number chain

All multi-function PCI devices will carry the [f<function>] number in the
device name, including the function 0 device.

When using PCI geography, The PCI domain is only prepended when it is not 0.

For USB devices the full chain of port numbers of hubs is composed. If the
name gets longer than the maximum number of 15 characters, the name is not
exported.
The usual USB configuration == 1 and interface == 0 values are suppressed.

PCI ethernet card with firmware index "1"::
* eno1

PCI ethernet card in hotplug slot with firmware index number::
* ens1

PCI ethernet multi-function card with 2 ports::
* enp2s0f0
* enp2s0f1

PCI wlan card::
* wlp3s0

USB built-in 3G modem::
* wwp0s29u1u4i6

USB Android phone::
* enp0s29u1u2
=====================

**ip=**__{dhcp|on|any|dhcp6|auto6}__::
    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

**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>.
=====================

**ip=**__<client-IP>__:[__<peer>__]:__<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. __<peer>__ is optional and is the address of the remote endpoint
    for pointopoint interfaces and it may be followed by a slash and a decimal
    number, encoding the network prefix length.
+
=====================
<macaddr>::: optionally **set** <macaddr> on the <interface>. This
cannot be used in conjunction with the **ifname** argument for the
same <interface>.
=====================

**ip=**__<client-IP>__:[__<peer>__]:__<gateway-IP>__:__<netmask>__:__<client_hostname>__:__<interface>__:__{none|off|dhcp|on|any|dhcp6|auto6|ibft}__[:[__<dns1>__][:__<dns2>__]]::
    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. __<peer>__ is optional and is the address of the remote endpoint
    for pointopoint interfaces and it may be followed by a slash and a decimal
    number, encoding the network prefix length.

**ifname=**__<interface>__:__<MAC>__::
    Assign network device name <interface> (ie "bootnet") to the NIC with
    MAC <MAC>.
+
WARNING: 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".

**rd.route=**__<net>__/__<netmask>__:__<gateway>__[:__<interface>__]::
    Add a static route with route options, which are separated by a colon.
    IPv6 addresses have to be put in brackets.
+
[listing]
.Example
--
    rd.route=192.168.200.0/24:192.168.100.222:ens10
    rd.route=192.168.200.0/24:192.168.100.222
    rd.route=192.168.200.0/24::ens10
    rd.route=[2001:DB8:3::/8]:[2001:DB8:2::1]:ens10
--

**bootdev=**__<interface>__::
    specify network interface to use routing and netroot information from.
    Required if multiple ip= lines are used.

**BOOTIF=**__<MAC>__::
    specify network interface to use routing and netroot information from.

**rd.bootif=0**::
    Disable BOOTIF parsing, which is provided by PXE

**nameserver=**__<IP>__ [**nameserver=**__<IP>__ ...]::
    specify nameserver(s) to use

**rd.peerdns=0**::
    Disable DNS setting of DHCP parameters.

**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=**\[_<server-ip>_:]__<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.
+
[listing]
.Example
--
    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=\[_<server-ip>_:]__<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 override the settings in _/etc/idmap.conf_.

**rd.net.dhcp.retry=**__<cnt>__::
    If this option is set, dracut will try to connect via dhcp <cnt> times before failing.
    Default is 1.

**rd.net.timeout.dhcp=**__<arg>__::
    If this option is set, dhclient is called with "-timeout <arg>".

**rd.net.timeout.iflink=**__<seconds>__::
    Wait <seconds> until link shows up. Default is 60 seconds.

**rd.net.timeout.ifup=**__<seconds>__::
    Wait <seconds> until link has state "UP". Default is 20 seconds.

**rd.net.timeout.route=**__<seconds>__::
    Wait <seconds> until route shows up. Default is 20 seconds.

**rd.net.timeout.ipv6dad=**__<seconds>__::
    Wait <seconds> until IPv6 DAD is finished. Default is 50 seconds.

**rd.net.timeout.ipv6auto=**__<seconds>__::
    Wait <seconds> until IPv6 automatic addresses are assigned. Default is 40 seconds.

**rd.net.timeout.carrier=**__<seconds>__::
    Wait <seconds> until carrier is recognized. Default is 5 seconds.

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
    link:$$http://tools.ietf.org/html/rfc4173#section-5$$[rfc4173].
+
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.
+
[listing]
.Example
--
root=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
--
+
If servername is an IPv6 address, it has to be put in brackets:
+
[listing]
.Example
--
root=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
--

**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:
+
[listing]
.Example
--
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:
+
[listing]
.Example
--
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.
+
[listing]
.Example
--
"netroot=iscsi rd.iscsi.firmware=1 rd.iscsi.param=node.session.timeo.replacement_timeout=30"
--
+
will result in
+
[listing]
--
iscsistart -b --param node.session.timeo.replacement_timeout=30
--

**rd.iscsi.ibft** **rd.iscsi.ibft=1**:
    Turn on iBFT autoconfiguration for the interfaces

**rd.iscsi.waitnet=0**:
    Turn off waiting for all interfaces to be up before trying to login to the iSCSI targets.

**rd.iscsi.testroute=0**:
    Turn off checking, if the route to the iSCSI target IP is possible before trying to login.

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/exportname>__[:__<fstype>__[:__<mountopts>__[:__<nbdopts>__]]]::
    mount nbd share from <server>.
+
NOTE:
    If "exportname" instead of "port" is given the standard port is used.
    Newer versions of nbd are only supported with "exportname".

**root=dhcp** with **dhcp** **root-path=**nbd:__<server>__:__<port/exportname>__[:__<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.
+
NOTE:
    If "exportname" instead of "port" is given the standard port is used.
    Newer versions of nbd are only supported with "exportname".

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.
+
[listing]
.Example
--
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.
+
[listing]
.Example
--
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
--

Booting live images
~~~~~~~~~~~~~~~~~~~
Dracut offers multiple options for live booted images:

=====================
SquashFS with read-only filesystem image::: The system will boot with a read
only filesystem from the SquashFS and apply a writable device-mapper snapshot
over the read only filesystem.  Using this method ensures a relatively fast
boot and lower RAM usage. Users **must be careful** to avoid writing too many
blocks to the snapshot volume.  Once the blocks of the snapshot overlay are
exhausted, the root filesystem becomes read only and may cause application
failures.  The overlay file is marked 'Overflow', and a difficult recovery is
required to repair and enlarge the overlay offline.  Non-persistent overlays
are sparse files in RAM that only consume content space as required blocks are
allocated.  They default to an apparent size of 32 GiB in RAM.  The size can be
adjusted with the **rd.live.overlay.size=** kernel command line option.
+
The filesystem structure is expected to be:
+
[listing]
--
squashfs.img          |  Squashfs from LiveCD .iso downloaded via network
   !(mount)
   /LiveOS
       |- rootfs.img  |  Filesystem image to mount read-only
            !(mount)
            /bin      |  Live filesystem
            /boot     |
            /dev      |
            ...       |
--
+
Dracut uses this method of live booting by default.  No additional command line
options are required other than **root=live:<URL>** to specify the location
of your squashed filesystem.
+
- The compressed SquashFS image can be copied during boot to RAM at
`/run/initramfs/squashed.img` by using the **rd.live.ram=1** option.
- A device with a persistent overlay can be booted read only by using the
**rd.live.overlay.readonly** option on the kernel command line.  This will
cause a temporary, writable overlay to be stacked over a read-only snapshot
of the root filesystem.
+
Uncompressed live filesystem image:::
When the live system was installed with the '--skipcompress' option of the
__livecd-iso-to-disk__ installation script for Live USB devices, the root
filesystem image, `rootfs.img`, is expanded on installation and no SquashFS
is involved during boot.
+
- If **rd.live.ram=1** is used in this situation, the full, uncompressed
root filesystem is copied during boot to `/run/initramfs/rootfs.img` in the
`/run` tmpfs.
+
- If **rd.live.overlay=none** is provided as a kernel command line option,
a writable, linear device-mapper target is created on boot with no overlay.

writable filesystem image:::
The system will retrieve a compressed filesystem image, extract it to
`/run/initramfs/fsimg/rootfs.img`, connect it to a loop device, create a
writable, linear device-mapper target at `/dev/mapper/live-rw`, and mount that
as a writable volume at `/`.  More RAM is required during boot but the live
filesystem is easier to manage if it becomes full.  Users can make a filesystem
image of any size and that size will be maintained when the system boots. There
is no persistence of root filesystem changes between boots with this option.
+
The filesystem structure is expected to be:
+
[listing]
--
rootfs.tgz            |  Compressed tarball containing fileystem image
   !(unpack)
   /rootfs.img        |  Filesystem image at /run/initramfs/fsimg/
      !(mount)
      /bin            |  Live filesystem
      /boot           |
      /dev            |
      ...             |
--
+
To use this boot option, ensure that **rd.writable.fsimg=1** is in your kernel
command line and add the **root=live:<URL>** to specify the location
of your compressed filesystem image tarball or SquashFS image.
=====================

**rd.writable.fsimg=**1::
Enables writable filesystem support.  The system will boot with a fully
writable (but non-persistent) filesystem without snapshots __(see notes above
about available live boot options)__.  You can use the **rootflags** option to
set mount options for the live filesystem as well __(see documentation about
rootflags in the **Standard** section above)__.
This implies that the whole image is copied to RAM before the boot continues.
+
NOTE: There must be enough free RAM available to hold the complete image.
+
This method is very suitable for diskless boots.

**root=**live:__<url>__::
Boots a live image retrieved from __<url>__.  Valid handlers: __http, https, ftp, torrent, tftp__.
+
[listing]
.Example
--
root=live:http://example.com/liveboot.img
root=live:ftp://ftp.example.com/liveboot.img
root=live:torrent://example.com/liveboot.img.torrent
--

**rd.live.debug=**1::
Enables debug output from the live boot process.

**rd.live.dir=**__<path>__::
Specifies the directory within the boot device where the squashfs.img or
rootfs.img can be found.  By default, this is __LiveOS__.

**rd.live.squashimg=**__<filename of SquashFS image>__::
Specifies the filename for a SquashFS image of the root filesystem.
By default, this is __squashfs.img__.

**rd.live.ram=**1::
Copy the complete image to RAM and use this for booting. This is useful
when the image resides on, i.e., a DVD which needs to be ejected later on.

**rd.live.overlay=**__<devspec>__:__(<pathspec>|auto)__|__none__::
Allow the usage of a permanent overlay.
- _<devspec>_ specifies the path to a device with a mountable filesystem.
- _<pathspec>_ is the path to a file within that filesystem, which shall be
used to persist the changes made to the device specified by the
**root=live:__<url>__** option.
- _none_ specifies no overlay when an uncompressed live root filesystem is
available.
If a persistent overlay is detected at the standard LiveOS path, the overlay &
overlay type detected (whether Device-mapper or OverlayFS) will be used.
+
[listing]
.Example
--
rd.live.overlay=/dev/sdb1:persistent-overlay.img
--

**rd.live.overlay.size=**__<size_MiB>__::
Specifies a non-persistent overlay size in MiB.  The default is _32768_.

**rd.live.overlay.readonly=**1::
Specifies a non-persistent, writable snapshot overlay to be stacked over a
read-only snapshot of the root filesystem, `/dev/mapper/live-ro`, or a read-
only loop device of a writable `rootfs.img`.

**rd.live.overlay.reset=**1::
Specifies that a persistent overlay should be reset on boot.  All root
filesystem changes are vacated by this action.

**rd.live.overlay.thin=**1::
Enables the usage of thin snapshots instead of classic dm snapshots.
The advantage of thin snapshots is that they support discards, and will free
blocks that are not claimed by the filesystem. In this use case, this means
that memory is given back to the kernel when the filesystem does not claim it
anymore.

**rd.live.overlay.overlayfs=**1::
Enables the use of the **OverlayFS** kernel module, if available, to provide a
copy-on-write union directory for the root filesystem.  OverlayFS overlays are
directories of the files that have changed on the read-only base (lower)
filesystem.  The root filesystem is provided through a special overlay type
mount that merges the lower and upper directories.  If an OverlayFS upper
directory is not present on the boot device, a tmpfs directory will be created
at /run/overlayfs to provide temporary storage.  Persistent storage can be
provided on vfat or msdos formatted devices by supplying the OverlayFS upper
directory within an embedded filesystem that supports the creation of trusted.*
extended attributes and provides a valid d_type in readdir responses, such as
with ext4 and xfs.  On non-vfat-formatted devices, a persistent OverlayFS
overlay can extend the available root filesystem storage up to the capacity of
the LiveOS device.

If a persistent overlay is detected at the standard LiveOS path, the overlay &
overlay type detected (whether OverlayFS or Device-mapper) will be used.

The **rd.live.overlay.readonly** option, which allows a persistent overlayfs to
be mounted read only through a higher level transient overlay directory, has
been implemented through the multiple lower layers feature of OverlayFS.


Plymouth Boot Splash
~~~~~~~~~~~~~~~~~~~~
**plymouth.enable=0**::
    disable the plymouth bootsplash completely.

**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.
+
[listing]
.Example
--
masterkey=/etc/keys/kmk-trusted.blob
--

**masterkeytype=**__<kernel master key type>__::
    Set the type of the kernel master key.
+
[listing]
.Example
--
masterkeytype=trusted
--

**evmkey=**__<EVM key path name>__::
    Set the path name of the EVM key.
+
[listing]
.Example
--
evmkey=/etc/keys/evm-trusted.blob
--

**ecryptfskey=**__<eCryptfs key path name>__::
    Set the path name of the eCryptfs key.
+
[listing]
.Example
--
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_NO_MULTIPATH: rd.multipath=0

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)