noble (7) dracut.cmdline.7.gz

Provided by: dracut-core_060+5-1ubuntu3.2_amd64 bug

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.

           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.

           Example.

               rootfstype=ext4

       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

           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
       Mount all mountable devices and search for ISO pointed by the argument. When the ISO is found set it up
       as a loop device. Device containing this ISO image will stay mounted at /run/initramfs/isoscandev. Using
       iso-scan/filename with a Fedora/Red Hat/CentOS Live iso should just work by copying the original kernel
       cmdline parameters.

       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 must 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 180 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.

       rd.shutdown.timeout.umount=<seconds>
           specify how long dracut should wait for an individual umount to finish during shutdown. This avoids
           the system from blocking when unmounting a file system cannot complete and waits indefinitely. Value
           0 means to wait forever. The default is 90 seconds.

   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=[0-5]
           Print memory usage info at various points, set the verbose level from 0 to 5.

               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 + memstrack summary
                       NOTE: memstrack is a memory tracing tool that tracks the total memory
                             consumption, and peak memory consumption of each kernel modules
                             and userspace progress during the whole initramfs runtime, report
                             is generated and the end of initramsfs run.
                   5 - /proc/meminfo + /proc/slabinfo + memstrack (with top memory stacktrace)
                       NOTE: memstrack (with top memory stacktrace) will print top memory
                             allocation stack traces during the whole initramfs runtime.

       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 before the defined breakpoint starts

       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.

           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.

           Example.

               rd.vconsole.font=eurlatgr

       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.

           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 all logical volumes in the the volume groups with the given name. rd.lvm.vg can be
           specified multiple times on the kernel command line.

       rd.lvm.lv=<volume group name>/<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.  <luks uuid> may be prefixed by the keyword keysource:, see rd.luks.key below.

       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

       rd.luks.timeout=<seconds>
           specify how long dracut should wait when waiting for the user to enter the password. This avoid
           blocking the boot if no password is entered. It does not apply to luks key. The default is 0, which
           means forever.

   crypto LUKS - key on removable device support
       NB: If systemd is included in the dracut initrd, dracut’s built in removable device keying support won’t
       work. systemd will prompt for a password from the console even if you’ve supplied rd.luks.key. You may be
       able to use standard systemd fstab(5) syntax to get the same effect. If you do need rd.luks.key to work,
       you will have to exclude the "systemd" dracut module and any modules that depend on it. See
       dracut.conf(5) and https://bugzilla.redhat.com/show_bug.cgi?id=905683 for more information.

       rd.luks.key=<keypath>[:<keydev>[:<luksdev>]]
           <keypath> is the pathname of a key file, relative to the root of the filesystem on some device. It’s
           REQUIRED. When <keypath> ends with .gpg it’s considered to be key encrypted symmetrically with GPG.
           You will be prompted for the GPG password on boot. GPG support comes with the crypt-gpg module, which
           needs to be added explicitly.

           <keydev> identifies the device on which the key file resides. It may be the kernel name of the device
           (should start with "/dev/"), a UUID (prefixed with "UUID=") or a label (prefix with "LABEL="). You
           don’t have to specify a 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 it’s not
           present, all block devices will be probed, which may significantly increase boot time.

           If <luksdev> is given, the specified key will only be used for the specified 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:

           Example.

               rd.luks.key=/foo/bar.key

           As you see, you can skip colons in such a case.

           Note
           Your LUKS partition must match your key file.

           dracut provides keys to cryptsetup with -d (an older alias for --key-file). This uses the entire
           binary content of the key file as part of the secret. If you pipe a password into cryptsetup without
           -d or --key-file, it will be treated as text user input, and only characters before the first newline
           will be used. Therefore, when you’re creating an encrypted partition for dracut to mount, and you
           pipe a key into cryptsetup luksFormat,you must use -d -.

           Here is an example for a key encrypted with GPG (warning: --batch-mode will overwrite the device
           without asking for confirmation):

               gpg --quiet --decrypt rootkey.gpg | \
               cryptsetup --batch-mode --key-file - \
                          luksFormat /dev/sda47

           If you use unencrypted key files, just use the key file pathname instead of the standard input. For a
           random key with 256 bits of entropy, you might use:

               head -32c /dev/urandom > rootkey.key
               cryptsetup --batch-mode --key-file rootkey.key \
                          luksFormat /dev/sda47

           You can also use regular key files on an encrypted keydev.

           Compared to using GPG encrypted keyfiles on an unencrypted device this provides the following
           advantages:

           •   you can unlock your disk(s) using multiple passphrases

           •   better security by not losing the key stretching mechanism

           To use an encrypted keydev you must ensure that it becomes available by using the keyword keysource,
           e.g. rd.luks.uuid=keysource:aaaa aaaa being the uuid of the encrypted keydev.

           Example:

           Lets assume you have three disks A, B and C with the uuids aaaa, bbbb and cccc. You want to unlock A
           and B using keyfile keyfile. The unlocked volumes be A', B' and C' with the uuids AAAA, BBBB and
           CCCC. keyfile is saved on C' as /keyfile.

           One luks keyslot of each A, B and C is setup with a passphrase. Another luks keyslot of each A and B
           is setup with keyfile.

           To boot this configuration you could use:

               rd.luks.uuid=aaaa
               rd.luks.uuid=bbbb
               rd.luks.uuid=keysource:cccc
               rd.luks.key=/keyfile:UUID=CCCC

           Dracut asks for the passphrase for C and uses the keyfile to unlock A and B. If getting the
           passphrase for C fails it falls back to asking for the passphrases for A and B.

           If you want C' to stay unlocked, specify a luks name for it, e.g. rd.luks.name=cccc=mykeys, otherwise
           it gets closed when not needed anymore.

       rd.luks.key.tout=0
           specify how many times dracut will try to read the keys specified in in rd.luk.key. This gives a
           chance to the removable device containing the key to initialise.

   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

       rd.multipath=default
           use default multipath settings

   FIPS
       rd.fips
           enable FIPS

       boot=<boot device>
           specify the device, where /boot is located.

           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

       The following options are supported by the network-legacy dracut module. Other network modules might
       support a slightly different set of options; refer to the documentation of the specific network module in
       use. For NetworkManager, see nm-initrd-generator(8).

       ip={dhcp|on|any|dhcp6|auto6|either6|link6|single-dhcp}

           dhcp|on|any
               get ip from dhcp server from all interfaces. If netroot=dhcp, loop sequentially through all
               interfaces (eth0, eth1, ...) and use the first with a valid DHCP root-path.

           single-dhcp
               Send DHCP on all available interfaces in parallel, as opposed to one after another. After the
               first DHCP response is received, stop DHCP on all other interfaces. This gives the fastest boot
               time by using the IP on interface for which DHCP succeeded first during early boot. Caveat: Does
               not apply to Network Manager.

           auto6
               IPv6 autoconfiguration

           dhcp6
               IPv6 DHCP

           either6
               if auto6 fails, then dhcp6

           link6
               bring up interface for IPv6 link-local addressing

       ip=<interface>:{dhcp|on|any|dhcp6|auto6|link6}[:[<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

           link6
               bring up interface for IPv6 link local address

           <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> (i.e. "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.

           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 <phydevice>. 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>[:<mtu>]]]
           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. if the mtu is specified, it
           will be set on the bond master. Bond without parameters assumes bond=bond0:eth0,eth1:mode=balance-rr

       team=<teammaster>:<teamslaves>[:<teamrunner>]
           Setup team device <teammaster> on top of <teamslaves>. <teamslaves> is a comma-separated list of
           physical (ethernet) interfaces. <teamrunner> is the runner type to be used (see teamd.conf(5));
           defaults to activebackup. Team without parameters assumes team=team0:eth0,eth1:activebackup

       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 separated by ",".

       root=nfs:[<server-ip>:]<root-dir>[:<nfs-options>], root=nfs4:[<server-ip>:]<root-dir>[:<nfs-options>],
       root={dhcp|dhcp6}
           netroot=dhcp alone directs initrd to look at the DHCP root-path where NFS options can be specified.

           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 10 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 rfc4173[1].

               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.

           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:

           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:

           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:

           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.login_retry_max=<num>
           maximum number of login retries

       rd.iscsi.param=<param>
           <param> will be passed as "--param <param>" to iscsistart. This parameter can be specified multiple
           times.

           Example.

               "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

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

       rd.iscsi.mp rd.iscsi.mp=1: Configure all iBFT interfaces, not only used for booting (multipath)

       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
       rd.fcoe=0
           disable FCoE and lldpad

       fcoe=<edd|interface|MAC>:{dcb|nodcb}:{fabric|vn2vn}
           Try to connect to a FCoE SAN through the NIC specified by <interface> or <MAC> or EDD settings. The
           second argument specifies if DCB should be used. The optional third argument specifies whether fabric
           or VN2VN mode should be used. This parameter can be specified multiple times.

               Note
               letters in the MAC-address must be lowercase!

   NVMf
       rd.nonvmf
           Disable NVMf

       rd.nvmf.nonbft
           Disable connecting to targets from the NVMe Boot Firmware Table. Without this parameter, NBFT
           connections will take precedence over rd.nvmf.discover.

       rd.nvmf.nostatic
           Disable connecting to targets that have been statically configured when the initramfs was built.
           Targets specified with rd.nvmf.discover on the kernel command line will still be tried.

       rd.nvmf.hostnqn=<hostNQN>
           NVMe host NQN to use

       rd.nvmf.hostid=<hostID>
           NVMe host id to use

       rd.nvmf.discover={rdma|fc|tcp},<traddr>,[<host_traddr>],[<trsvcid>]
           Discover and connect to a NVMe-over-Fabric controller specified by <traddr> and the optionally
           <host_traddr> or <trsvcid>. The first argument specifies the transport to use; currently only rdma,
           fc, or tcp are supported. This parameter can be specified multiple times.

           Examples.

               rd.nvmf.discover=tcp,192.168.10.10,,4420
               rd.nvmf.discover=fc,nn-0x201700a05634f5bf:pn-0x201900a05634f5bf,nn-0x200000109b579ef3:pn-0x100000109b579ef3

       rd.nvmf.discover=fc,auto
           This special syntax determines that Fibre Channel autodiscovery is to be used rather than regular
           NVMe discovery. It takes precedence over all other rd.nvmf.discover= arguments.

   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=/dev/root netroot=dhcp with dhcp
       root-path=nbd:<server>:<port/exportname>[:<fstype>[:<mountopts>[:<nbdopts>]]]
           netroot=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".

   VIRTIOFS
       root=virtiofs:<mount-tag>
           mount virtiofs share using the tag <mount-tag>. The tag name is arbitrary and must match the tag
           given in the qemu -device command.

       rootfstype=virtiofs root=<mount-tag>
           mount virtiofs share using the tag <mount-tag>. The tag name is arbitrary and must match the tag
           given in the qemu -device command.

       Both formats are supported by the virtiofs dracut module. See https://gitlab.com/virtio-fs/virtiofsd for
       more information.

       Example.

           root=virtiofs:host rw

   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.

       rd.zfcp=<zfcp adaptor device bus ID>
           If NPIV is enabled and the allow_lun_scan parameter to the zfcp module is set to Y then the zfcp
           adaptor will be initiating a scan internally and the <WWPN> and <FCPLUN> parameters can be omitted.

           Example.

               rd.zfcp=0.0.4000,0x5005076300C213e9,0x5022000000000000
               rd.zfcp=0.0.4000

       rd.zfcp.conf=0
           ignore zfcp.conf included in the initramfs

   ZNET
       rd.znet=<nettype>,<subchannels>,<options>
           The whole parameter is appended to /etc/ccw.conf, which is used on RHEL/Fedora with ccw_init, which
           is called from udev for certain devices on z-series. rd.znet can be specified multiple times on the
           kernel command line.

       rd.znet_ifname=<ifname>:<subchannels>
           Assign network device name <interface> (i.e. "bootnet") to the NIC corresponds to the subchannels.
           This is useful when dracut’s default "ifname=" doesn’t work due to device having a changing MAC
           address.

           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 or an OverlayFS overlay mount for the read-only base filesystem. This method ensures a
           relatively fast boot and lower RAM usage. Users must be careful to avoid writing too many blocks to a
           snapshot volume. Once the blocks of the snapshot overlay are exhausted, the root filesystem becomes
           read-only and may cause application failures. The snapshot 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 traditionally expected to be:

               squashfs.img          |  SquashFS from LiveCD .iso
                  !(mount)
                  /LiveOS
                      |- rootfs.img  |  Filesystem image to mount read-only
                           !(mount)
                           /bin      |  Live filesystem
                           /boot     |
                           /dev      |
                           ...       |

           For OverlayFS mount overlays, the filesystem structure may also be a direct compression of the root
           filesystem:

               squashfs.img          |  SquashFS from LiveCD .iso
                  !(mount)
                  /bin               |  Live filesystem
                  /boot              |
                  /dev               |
                  ...                |

           Dracut uses one of the overlay methods 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 either cause a temporary, writable overlay to be
               stacked over a read-only snapshot of the root filesystem or the OverlayFS mount will use an
               additional lower layer with 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:

               rootfs.tgz            |  Compressed tarball containing filesystem 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.

       rd.minmem=<megabyte>
           Specify minimum free RAM in MB after copying a live disk image into memory. The default is 1024.

           This parameter only applies together with the parameters rd.writable.fsimg or rd.live.ram.

       root=live:<url>
           Boots a live image retrieved from <url>. Requires the dracut livenet module. Valid handlers: http,
           https, ftp, torrent, tftp.

           Examples.

               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,
           e.g., a DVD which needs to be ejected later on.

       rd.live.overlay={<devspec>[:{<pathspec>|auto}]|none}
           Manage 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.

               The default pathspec, when auto or no :<pathspec> is given, is
               /<rd.live.dir>/overlay-<label>-<uuid>, where <label> is the device LABEL, and <uuid> is the
               device UUID. * none (the word itself) specifies that no overlay will be used, such as when an
               uncompressed, writable 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.

           Examples.

               rd.live.overlay=/dev/sdb1:persistent-overlay.img
               rd.live.overlay=UUID=99440c1f-8daa-41bf-b965-b7240a8996f4

       rd.live.overlay.cowfs=[btrfs|ext4|xfs]
           Specifies the filesystem to use when formatting the overlay partition. The default is ext4.

       rd.live.overlay.size=<size_MiB>
           Specifies a non-persistent Device-mapper overlay size in MiB. The default is 32768.

       rd.live.overlay.readonly=1
           This is used to boot with a normally read-write persistent overlay in a read-only mode. With this
           option, either an additional, non-persistent, writable snapshot overlay will be stacked over a
           read-only snapshot, /dev/mapper/live-ro, of the base filesystem with the persistent overlay, or a
           read-only loop device, in the case of a writable rootfs.img, or an OverlayFS mount will use the
           persistent overlay directory linked at /run/overlayfs-r as an additional lower layer along with the
           base root filesystem and apply a transient, writable upper directory overlay, in order to complete
           the booted root filesystem.

       rd.live.overlay.reset=1
           Specifies that a persistent overlay should be reset on boot. All previous 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 disk 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.

   ZIPL
       rd.zipl=<path to blockdevice>
           Update the dracut commandline with the values found in the dracut-cmdline.conf file on the given
           device. The values are merged into the existing commandline values and the udev events are
           regenerated.

           Example.

               rd.zipl=UUID=0fb28157-99e3-4395-adef-da3f7d44835a

   CIO_IGNORE
       rd.cio_accept=<device-ids>
           Remove the devices listed in <device-ids> from the default cio_ignore kernel command-line settings.
           <device-ids> is a list of comma-separated CCW device ids. The default for this value is taken from
           the /boot/zipl/active_devices.txt file.

           Example.

               rd.cio_accept=0.0.0180,0.0.0800,0.0.0801,0.0.0802

   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.

           Example.

               masterkey=/etc/keys/kmk-trusted.blob

       masterkeytype=<kernel master key type>
           Set the type of the kernel master key.

           Example.

               masterkeytype=trusted

       evmkey=<EVM HMAC key path name>
           Set the path name of the EVM HMAC key.

           Example.

               evmkey=/etc/keys/evm-trusted.blob

       evmx509=<EVM X.509 cert path name>
           Set the path name of the EVM X.509 certificate.

           Example.

               evmx509=/etc/keys/x509_evm.der

       ecryptfskey=<eCryptfs key path name>
           Set the path name of the eCryptfs key.

           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.znet

       rd_CCW
           rd.znet

       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_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)

NOTES

        1. rfc4173
           http://tools.ietf.org/html/rfc4173#section-5