dracut.cmdline(7) - dracut kernel command line options



  • DRACUT.CMDLINE(7)                   dracut                   DRACUT.CMDLINE(7)
    
    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=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
    
               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.
    
           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.
    
       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.
    
               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=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.
    
               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
    <standard input>:1344: warning [p 12, 9.5i]: can't break line
    <standard input>:1351: warning [p 12, 10.8i]: can't break line
               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
    
           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
           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:
    
               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:
    
                       gpg --quiet --decrypt rootkey.gpg | \
                       cryptsetup -d - -v --cipher serpent-cbc-essiv:sha256 \
                       --key-size 256 luksFormat /dev/sda3
    
                   If you use plain keys, just add path to -d option:
    
                       cryptsetup -d rootkey.key -v --cipher serpent-cbc-essiv:sha256 \
                        --key-size 256 luksFormat /dev/sda3
    
       MD RAID
           rd.md=0
               disable MD RAID detection
    
           rd.md.imsm=0
               disable MD RAID for imsm/isw raids, use DM RAID instead
    
           rd.md.ddf=0
               disable MD RAID for SNIA ddf raids, use DM RAID instead
    
           rd.md.conf=0
               ignore mdadm.conf included in initramfs
    
           rd.md.waitclean=1
               wait for any resync, recovery, or reshape activity to finish before
               continuing
    
           rd.md.uuid=<md raid uuid>
               only activate the raid sets with the given UUID. This parameter can
               be specified multiple times.
    
       DM RAID
           rd.dm=0
               disable DM RAID detection
    
           rd.dm.uuid=<dm raid uuid>
               only activate the raid sets with the given UUID. This parameter can
               be specified multiple times.
    
       MULTIPATH
           rd.multipath=0
               disable multipath detection
    
       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
    
           ip={dhcp|on|any|dhcp6|auto6|either6}
    
               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
    
               either6
                   if auto6 fails, then dhcp6
    
           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.
    
               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>[:<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>
               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 separated 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.
    
               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
               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.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}:{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!
    
       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.
    
           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.
    
               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.
    
           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
                   /<<b>rd.live.dir</b>>/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.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 key path name>
               Set the path name of the EVM key.
    
               Example.
    
                   evmkey=/etc/keys/evm-trusted.blob
    
           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_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)
    
    NOTES
            1. rfc4173
               http://tools.ietf.org/html/rfc4173#section-5
    
    dracut                            10/09/2018                 DRACUT.CMDLINE(7)
    

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