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DRACUT.CMDLINE(7) - Linux man page online | Overview, conventions, and miscellany

Dracut kernel command line options.

Chapter
2018-01-18
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:LAB ↲ EL=$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 parameter can be specified multiple times. rd.luks.allow-discards=<luks uuid> Allow using of discards (TRIM) requests for LUKS partitions with the given UUID. Any "luks-" of the LUKS UUID is removed before comparing to <luks uuid>. The comparisons also matches, if <luks uuid> is only the beginning of the LUKS UUID, so you don’t have to specify the full UUID. This parameter can be specified multiple times. rd.luks.allow-discards Allow using of discards (TRIM) requests on all LUKS partitions. rd.luks.crypttab=0 do not check, if LUKS partition is in /etc/crypttab crypto LUKS - key on removable device support rd.luks.key=<keypath>:<keydev>:<luksdev> keypath is a path to key file to look for. It’s REQUIRED. When keypath ends with .gpg it’s considered to be key encrypted symmetrically with GPG. You will be prompted for password on boot. GPG support comes with crypt-gpg module which needs to be added explicitly. keydev is a device on which key file resides. It might be kernel name of devices (should start with "/dev/"), UUID (prefixed with "UUID=") or label (prefix with "LABEL="). You don’t have to specify full UUID. Just its beginning will suffice, even if its ambiguous. All matching devices will be probed. This parameter is recommended, but not required. If not present, all block devices will be probed, which may significantly increase boot time. If luksdev is given, the specified key will only be applied for that LUKS device. Possible values are the same as for keydev. Unless you have several LUKS devices, you don’t have to specify this parameter. The simplest usage is: 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} dhcp|on|any get ip from dhcp server from all interfaces. If root=dhcp, loop sequentially through all interfaces (eth0, eth1, ...) and use the first with a valid DHCP root-path. auto6 IPv6 autoconfiguration dhcp6 IPv6 DHCP ip=<interface>:{dhcp|on|any|dhcp6|auto6}[:[<mtu>][:<macaddr>]] This parameter can be specified multiple times. dhcp|on|any|dhcp6 get ip from dhcp server on a specific interface auto6 do IPv6 autoconfiguration <macaddr> optionally set <macaddr> on the <interface>. This cannot be used in conjunction with the ifname argument for the same <interface>. ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|o ↲ n|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|o ↲ n|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 seperated by ",". root=nfs:[<server-ip>:]<root-dir>[:<nfs-options>], root=nfs4:[<server-ip>:]<root-dir>[:<nfs-options>], root={dhcp|dhcp6} root=dhcp alone directs initrd to look at the DHCP root-path where NFS options can be specified. 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>]:[<po ↲ rt>][:[<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.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_time ↲ out=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 over the read only filesystem. Using this method ensures a relatively fast boot and lower RAM usage. Users must be careful to avoid writing too many blocks to the snapshot volume. Once the blocks of the snapshot overlay are exhausted, the root filesystem becomes read only and may cause application failures. The overlay file is marked Overflow, and a difficult recovery is required to repair and enlarge the overlay offline. Non-persistent overlays are sparse files in RAM that only consume content space as required blocks are allocated. They default to an apparent size of 32 GiB in RAM. The size can be adjusted with the rd.live.overlay.size= kernel command line option. The filesystem structure is expected to be: squashfs.img | Squashfs from LiveCD .iso downloaded via network !(mount) /LiveOS |- rootfs.img | Filesystem image to mount read-only !(mount) /bin | Live filesystem /boot | /dev | ... | Dracut uses this method of live booting by default. No additional command line options are required other than root=live:<URL> to specify the location of your squashed filesystem. · The compressed SquashFS image can be copied during boot to RAM at /run/initramfs/squashed.img by using the rd.live.ram=1 option. · A device with a persistent overlay can be booted read only by using the rd.live.overlay.readonly option on the kernel command line. This will cause a temporary, writable overlay to be stacked over a read-only snapshot of the root filesystem. Uncompressed live filesystem image When the live system was installed with the --skipcompress option of the livecd-iso-to-disk installation script for Live USB devices, the root filesystem image, rootfs.img, is expanded on installation and no SquashFS is involved during boot. · If rd.live.ram=1 is used in this situation, the full, uncompressed root filesystem is copied during boot to /run/initramfs/rootfs.img in the /run tmpfs. · If rd.live.overlay=none is provided as a kernel command line option, a writable, linear device-mapper target is created on boot with no overlay. writable filesystem image The system will retrieve a compressed filesystem image, extract it to /run/initramfs/fsimg/rootfs.img, connect it to a loop device, create a writable, linear device-mapper target at /dev/mapper/live-rw, and mount that as a writable volume at /. More RAM is required during boot but the live filesystem is easier to manage if it becomes full. Users can make a filesystem image of any size and that size will be maintained when the system boots. There is no persistence of root filesystem changes between boots with this option. The filesystem structure is expected to be: rootfs.tgz | Compressed tarball containing fileystem image !(unpack) /rootfs.img | Filesystem image at /run/initramfs/fsimg/ !(mount) /bin | Live filesystem /boot | /dev | ... | To use this boot option, ensure that rd.writable.fsimg=1 is in your kernel command line and add the root=live:<URL> to specify the location of your compressed filesystem image tarball or SquashFS image. rd.writable.fsimg=1 Enables writable filesystem support. The system will boot with a fully writable (but non-persistent) filesystem without snapshots (see notes above about available live boot options). You can use the rootflags option to set mount options for the live filesystem as well (see documentation about rootflags in the Standard section above). This implies that the whole image is copied to RAM before the boot continues. Note There must be enough free RAM available to hold the complete image. This method is very suitable for diskless boots. root=live:<url> Boots a live image retrieved from <url>. Valid handlers: http, https, ftp, torrent, tftp. Example. root=live:http://example.com/liveboot.img root=live:ftp://ftp.example.com/liveboot.img root=live:torrent://example.com/liveboot.img.torrent rd.live.debug=1 Enables debug output from the live boot process. rd.live.dir=<path> Specifies the directory within the boot device where the squashfs.img or rootfs.img can be found. By default, this is LiveOS. rd.live.squashimg=<filename of SquashFS image> Specifies the filename for a SquashFS image of the root filesystem. By default, this is squashfs.img. rd.live.ram=1 Copy the complete image to RAM and use this for booting. This is useful when the image resides on, i.e., a DVD which needs to be ejected later on. rd.live.overlay=<devspec>:(<pathspec>|auto)|none Allow the usage of a permanent overlay. · <devspec> specifies the path to a device with a mountable filesystem. · <pathspec> is the path to a file within that filesystem, which shall be used to persist the changes made to the device specified by the root=live:<url> option. · none specifies no overlay when an uncompressed live root filesystem is available. If a persistent overlay is detected at the standard LiveOS path, the overlay & overlay type detected (whether Device-mapper or OverlayFS) will be used. Example. rd.live.overlay=/dev/sdb1:persistent-overlay.img rd.live.overlay.size=<size_MiB> Specifies a non-persistent overlay size in MiB. The default is 32768. rd.live.overlay.readonly=1 Specifies a non-persistent, writable snapshot overlay to be stacked over a read-only snapshot of the root filesystem, /dev/mapper/live-ro, or a read- only loop device of a writable rootfs.img. rd.live.overlay.reset=1 Specifies that a persistent overlay should be reset on boot. All root filesystem changes are vacated by this action. rd.live.overlay.thin=1 Enables the usage of thin snapshots instead of classic dm snapshots. The advantage of thin snapshots is that they support discards, and will free blocks that are not claimed by the filesystem. In this use case, this means that memory is given back to the kernel when the filesystem does not claim it anymore. rd.live.overlay.overlayfs=1 Enables the use of the OverlayFS kernel module, if available, to provide a copy-on-write union directory for the root filesystem. OverlayFS overlays are directories of the files that have changed on the read-only base (lower) filesystem. The root filesystem is provided through a special overlay type mount that merges the lower and upper directories. If an OverlayFS upper directory is not present on the boot device, a tmpfs directory will be created at /run/overlayfs to provide temporary storage. Persistent storage can be provided on vfat or msdos formatted devices by supplying the OverlayFS upper directory within an embedded filesystem that supports the creation of trusted.* extended attributes and provides a valid d_type in readdir responses, such as with ext4 and xfs. On non-vfat-formatted devices, a persistent OverlayFS overlay can extend the available root filesystem storage up to the capacity of the LiveOS device. If a persistent overlay is detected at the standard LiveOS path, the overlay & overlay type detected (whether OverlayFS or Device-mapper) will be used. The rd.live.overlay.readonly option, which allows a persistent overlayfs to be mounted read only through a higher level transient overlay directory, has been implemented through the multiple lower layers feature of OverlayFS. 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 2018-01-18 DRACUT.CMDLINE(7)
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dracut.cmdline(7) referred by dracut(8) | dracut.conf(5) | fai-cd(8) | kernel-command-line(7)
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