Dracut kernel command line parameters
Limitations
- Command line length: 2048
- dhcp root-path: 255
Configuration in initrd
/conf/conf.d/*
Command line options can override values set here
Standard
init=<path to real init>
root=<path to blockdevice>
Specify e.g. /dev/sda1 or /dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
DHCP
root=dhcp
Get IP from dhcp server, root-path option from dhcp specifies root location.
NFSv3
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. nfs-options can be appended with the prefix ":" or ","
root=dhcp
root=dhcp alone directs initrd to look at the DHCP root-path where NFS options can be specified.
root-path=<server-ip>:<root-dir>[,<nfs-options>]
Deprecated
root=/dev/nfs nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
Kernel Documentation/filesystems/nfsroot.txt defines this method. This is supported by dracut but not recommended.
NFSv4
root=nfs4:[<server-ip>:]<root-dir>[:<nfs-options>]
mount nfsv4 share from <server-ip>:/<root-dir>. If no server-ip is given, use dhcp next_server. nfs-options can be appended with the prefix ":" or ","
root=dhcp
iSCSI
root=iscsi:[<servername>]:[<protocol>]:[<port>]:[<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 (Section 7). 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.RFC4173
root=??? iscsiroot=...::
root=??? iscsi_initiator= iscsi_target_name= iscsi_target_ip= iscsi_target_port= iscsi_target_group= iscsi_username= iscsi_password= iscsi_in_username= iscsi_in_password=::
root=??? iscsi_firmware::
NBD
root=nbd:<server>:<port>[:<fstype>][:<mountopts>]
Mount nbd share from <server>.
root=dhcp
Network
ip=[dhcp|on|any]
ip=<interface>:[dhcp|on|any]
Get ip from dhcp server on a specific interface.
ip=<client-IP-number>:<gateway-IP-number>:<netmask>:<client-hostname>:<interface>:[dhcp|on|any|]
Explicit network configuration
Misc
rdblacklist=<modulename>
TBD: do not load modulename.
Debug
rdinitdebug
set -x for the dracut shell.
rdbreak=[pre-udev|pre-mount|mount|pre-pivot|]
Drop the shell on defined breakpoint.
rdudevinfo
Set udev to loglevel info.
rdudevdebug
Set udev to loglevel debug.
rdnetdebug
Debug network scripts in dracut.