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== Configuration in initrd ==
 
  
<pre>/conf/conf.d/* </pre>
 
{{admon/note|Command line options can override values set here}}
 
  
 
== Standard ==
 
== Standard ==

Revision as of 15:54, 17 July 2009

Dracut kernel command line parameters

The root filesystem used by the kernel is specified in the boot configuration file, as always. The traditional root=/dev/hda1 style device specification is allowed. If a label is used, as in root=LABEL=rootPart the initrd will search all available devices for an ext2 or ext3 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.

Limitations

  • Command line length: 2048
  • dhcp root-path: 255



Standard

init=<path to real init>
root=<path to blockdevice>
Note.png
Specify e.g. /dev/sda1 or /dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1

DHCP

root=dhcp
Note.png
Get IP from dhcp server, root-path option from dhcp specifies root location.

NFSv3

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

iSCSI

root=iscsi:[<servername>]:[<protocol>]:[<port>]:[<LUN>]:<targetname>::
Note.png
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>]
Note.png
Mount nbd share from <server>.
root=dhcp
Note.png
root-path=nbd:<server>:<port>[:<fstype>][:<mountopts>]. 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.

Network

ip=[dhcp|on|any]
Note.png
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.
ip=<interface>:[dhcp|on|any]
Note.png
Get ip from dhcp server on a specific interface.
ip=<client-IP-number>:<gateway-IP-number>:<netmask>:<client-hostname>:<interface>:[dhcp|on|any|]
Note.png
Explicit network configuration

Misc

rdblacklist=<modulename>
Note.png
TBD: do not load modulename.

Debug

rdinitdebug
Note.png
set -x for the dracut shell.
rdbreak=[pre-udev|pre-mount|mount|pre-pivot|]
Note.png
Drop the shell on defined breakpoint.
rdudevinfo
Note.png
Set udev to loglevel info.
rdudevdebug
Note.png
Set udev to loglevel debug.
rdnetdebug
Note.png
Debug network scripts in dracut.