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.
rootflags=<mount options>
specify additional mount options for the root filesystem.
If not set, /etc/fstab of the real root will be parsed for special
mount options and mounted accordingly.
ro
force mounting / and /usr (if it is a
separate device) read-only. If none of ro and rw is present, both are mounted
according to /etc/fstab.
rw
force mounting / and /usr (if it is a
separate device) read-write. See also ro option.
rootfallback=<path to blockdevice>
specify the block device to use as the root filesystem,
if the normal root cannot be found. This can only be a simple block device
with a simple file system, for which the filesystem driver is either compiled
in, or added manually to the initramfs. This parameter can be specified
multiple times.
rd.auto rd.auto=1
enable autoassembly of special devices like cryptoLUKS,
dmraid, mdraid or lvm. Default is off as of dracut version >= 024.
rd.hostonly=0
removes all compiled in configuration of the host system
the initramfs image was built on. This helps booting, if any disk layout
changed, especially in combination with rd.auto or other parameters specifying
the layout.
rd.cmdline=ask
prompts the user for additional kernel command line
parameters
rd.fstab=0
do not honor special mount options for the root
filesystem found in /etc/fstab of the real root.
resume=<path to resume partition>
resume from a swap partition
Example.
resume=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
resume=/dev/disk/by-uuid/3f5ad593-4546-4a94-a374-bcfb68aa11f7
resume=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
rd.skipfsck
skip fsck for rootfs and /usr. If you’re
mounting /usr read-only and the init system performs fsck before
remount, you might want to use this option to avoid duplication.
iso-scan/filename¶
Mount all mountable devices and search for ISO pointed by the
argument. When the ISO is found set it up as a loop device. Device
containing this ISO image will stay mounted at /run/initramfs/isoscandev.
Using iso-scan/filename with a Fedora/Red Hat/CentOS Live iso should just
work by copying the original kernel cmdline parameters.
Example.
menuentry 'Live Fedora 20' --class fedora --class gnu-linux --class gnu --class os {
set isolabel=Fedora-Live-LXDE-x86_64-20-1
set isofile="/boot/iso/Fedora-Live-LXDE-x86_64-20-1.iso"
loopback loop $isofile
linux (loop)/isolinux/vmlinuz0 boot=isolinux iso-scan/filename=$isofile root=live:LABEL=$isolabel ro rd.live.image quiet rhgb
initrd (loop)/isolinux/initrd0.img
}
Misc¶
rd.emergency=[reboot|poweroff|halt]
specify, what action to execute in case of a critical
failure. rd.shell=0 must also be specified.
rd.driver.blacklist=<drivername>[,<drivername>,...]
do not load kernel module <drivername>. This
parameter can be specified multiple times.
rd.driver.pre=<drivername>[,<drivername>,...]
force loading kernel module <drivername>. This
parameter can be specified multiple times.
rd.driver.post=<drivername>[,<drivername>,...]
force loading kernel module <drivername> after all
automatic loading modules have been loaded. This parameter can be specified
multiple times.
rd.retry=<seconds>
specify how long dracut should retry the initqueue to
configure devices. The default is 180 seconds. After 2/3 of the time, degraded
raids are force started. If you have hardware, which takes a very long time to
announce its drives, you might want to extend this value.
rd.timeout=<seconds>
specify how long dracut should wait for devices to
appear. The default is 0, which means forever. Note that this
timeout should be longer than rd.retry to allow for proper
configuration.
rd.noverifyssl
accept self-signed certificates for ssl downloads.
rd.ctty=<terminal device>
specify the controlling terminal for the console. This is
useful, if you have multiple "console=" arguments.
rd.shutdown.timeout.umount=<seconds>
specify how long dracut should wait for an individual
umount to finish during shutdown. This avoids the system from blocking when
unmounting a file system cannot complete and waits indefinitely. Value
0 means to wait forever. The default is 90 seconds.
Debug¶
If you are dropped to an emergency shell, the file
/run/initramfs/rdsosreport.txt is created, which can be saved to a
(to be mounted by hand) partition (usually /boot) or a USB stick. Additional
debugging info can be produced by adding rd.debug to the kernel
command line. /run/initramfs/rdsosreport.txt contains all logs and
the output of some tools. It should be attached to any report about dracut
problems.
rd.info
print informational output though "quiet" is
set
rd.shell
allow dropping to a shell, if root mounting fails
rd.debug
set -x for the dracut shell. If systemd is active in the
initramfs, all output is logged to the systemd journal, which you can inspect
with "journalctl -ab". If systemd is not active, the logs are
written to dmesg and /run/initramfs/init.log. If "quiet" is
set, it also logs to the console.
rd.memdebug=[0-5]
Print memory usage info at various points, set the
verbose level from 0 to 5.
Higher level means more debugging output:
0 - no output
1 - partial /proc/meminfo
2 - /proc/meminfo
3 - /proc/meminfo + /proc/slabinfo
4 - /proc/meminfo + /proc/slabinfo + memstrack summary
NOTE: memstrack is a memory tracing tool that tracks the total memory
consumption, and peak memory consumption of each kernel modules
and userspace progress during the whole initramfs runtime, report
is genereted and the end of initramsfs run.
5 - /proc/meminfo + /proc/slabinfo + memstrack (with top memory stacktrace)
NOTE: memstrack (with top memory stacktrace) will print top memory
allocation stack traces during the whole initramfs runtime.
rd.break
drop to a shell at the end
rd.break={cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup}
drop to a shell before the defined breakpoint
starts
rd.udev.info
set udev to loglevel info
rd.udev.debug
set udev to loglevel debug
I18N¶
rd.vconsole.keymap=<keymap base file name>
keyboard translation table loaded by loadkeys; taken from
keymaps directory; will be written as KEYMAP to
/etc/vconsole.conf in
the initramfs.
Example.
rd.vconsole.keymap=de-latin1-nodeadkeys
rd.vconsole.keymap.ext=<list of keymap base file
names>
list of extra keymaps to bo loaded (sep. by space); will
be written as EXT_KEYMAP to /etc/vconsole.conf in the initramfs
rd.vconsole.unicode
boolean, indicating UTF-8 mode; will be written as
UNICODE to /etc/vconsole.conf in the initramfs
rd.vconsole.font=<font base file name>
console font; taken from consolefonts directory; will be
written as FONT to
/etc/vconsole.conf in the initramfs.
Example.
rd.vconsole.font=eurlatgr
rd.vconsole.font.map=<console map base file
name>
see description of -m parameter in setfont manual;
taken from consoletrans directory; will be written as FONT_MAP to
/etc/vconsole.conf in the initramfs
rd.vconsole.font.unimap=<unicode table base file
name>
see description of -u parameter in setfont manual;
taken from unimaps directory; will be written as FONT_UNIMAP to
/etc/vconsole.conf in the initramfs
rd.locale.LANG=<locale>
taken from the environment; if no UNICODE is defined we
set its value in basis of LANG value (whether it ends with ".utf8"
(or similar) or not); will be written as LANG to
/etc/locale.conf in
the initramfs.
Example.
rd.locale.LANG=pl_PL.utf8
rd.locale.LC_ALL=<locale>
taken from the environment; will be written as LC_ALL to
/etc/locale.conf in the initramfs
LVM¶
rd.lvm=0
disable LVM detection
rd.lvm.vg=<volume group name>
only activate all logical volumes in the the volume
groups with the given name. rd.lvm.vg can be specified multiple times on the
kernel command line.
rd.lvm.lv=<volume group name>/<logical volume
name>
only activate the logical volumes with the given name.
rd.lvm.lv can be specified multiple times on the kernel command line.
rd.lvm.conf=0
remove any /etc/lvm/lvm.conf, which may exist in
the initramfs
crypto LUKS¶
rd.luks=0
disable crypto LUKS detection
rd.luks.uuid=<luks uuid>
only activate the LUKS partitions with the given UUID.
Any "luks-" of the LUKS UUID is removed before comparing to
<luks uuid>. The comparisons also matches, if <luks
uuid> is only the beginning of the LUKS UUID, so you don’t have
to specify the full UUID. This parameter can be specified multiple times.
<luks uuid> may be prefixed by the keyword keysource:, see
rd.luks.key below.
rd.luks.allow-discards=<luks uuid>
Allow using of discards (TRIM) requests for LUKS
partitions with the given UUID. Any "luks-" of the LUKS UUID is
removed before comparing to <luks uuid>. The comparisons also
matches, if <luks uuid> is only the beginning of the LUKS UUID,
so you don’t have to specify the full UUID. This parameter can be
specified multiple times.
rd.luks.allow-discards
Allow using of discards (TRIM) requests on all LUKS
partitions.
rd.luks.crypttab=0
do not check, if LUKS partition is in
/etc/crypttab
rd.luks.timeout=<seconds>
specify how long dracut should wait when waiting for the
user to enter the password. This avoid blocking the boot if no password is
entered. It does not apply to luks key. The default is 0, which means
forever.
crypto LUKS - key on removable device support¶
NB: If systemd is included in the dracut initrd, dracut’s
built in removable device keying support won’t work. systemd will
prompt for a password from the console even if you’ve supplied
rd.luks.key. You may be able to use standard systemd fstab(5)
syntax to get the same effect. If you do need rd.luks.key to work,
you will have to exclude the "systemd" dracut module and any
modules that depend on it. See dracut.conf(5) and
https://bugzilla.redhat.com/show_bug.cgi?id=905683 for more
information.
rd.luks.key=<keypath>[:<keydev>[:<luksdev>]]
<keypath> is the pathname of a key file,
relative to the root of the filesystem on some device. It’s REQUIRED.
When
<keypath> ends with
.gpg it’s considered to be
key encrypted symmetrically with GPG. You will be prompted for the GPG
password on boot. GPG support comes with the
crypt-gpg module, which
needs to be added explicitly.
<keydev> identifies the device on which the key file
resides. It may be the kernel name of the device (should start with
"/dev/"), a UUID (prefixed with "UUID=") or a label
(prefix with "LABEL="). You don’t have to specify a full
UUID. Just its beginning will suffice, even if its ambiguous. All matching
devices will be probed. This parameter is recommended, but not required. If
it’s not present, all block devices will be probed, which may
significantly increase boot time.
If <luksdev> is given, the specified key will only be
used for the specified LUKS device. Possible values are the same as for
<keydev>. Unless you have several LUKS devices, you
don’t have to specify this parameter. The simplest usage is:
Example.
As you see, you can skip colons in such a case.
Note
Your LUKS partition must match your key file.
dracut provides keys to cryptsetup with -d (an older alias
for --key-file). This uses the entire binary content of the key file
as part of the secret. If you pipe a password into cryptsetup without
-d or --key-file, it will be treated as text user input, and
only characters before the first newline will be used. Therefore, when
you’re creating an encrypted partition for dracut to mount, and you
pipe a key into cryptsetup luksFormat,you must use -d -.
Here is an example for a key encrypted with GPG (warning:
--batch-mode will overwrite the device without asking for
confirmation):
gpg --quiet --decrypt rootkey.gpg | \
cryptsetup --batch-mode --key-file - \
luksFormat /dev/sda47
If you use unencrypted key files, just use the key file pathname
instead of the standard input. For a random key with 256 bits of entropy,
you might use:
head -32c /dev/urandom > rootkey.key
cryptsetup --batch-mode --key-file rootkey.key \
luksFormat /dev/sda47
You can also use regular key files on an encrypted
keydev.
Compared to using GPG encrypted keyfiles on an unencrypted device
this provides the following advantages:
•you can unlock your disk(s) using multiple
passphrases
•better security by not loosing the key stretching
mechanism
To use an encrypted keydev you must ensure that it
becomes available by using the keyword keysource, e.g.
rd.luks.uuid=keysource:aaaa aaaa being the uuid of the encrypted
keydev.
Example:
Lets assume you have three disks A, B and C
with the uuids aaaa, bbbb and cccc. You want to unlock
A and B using keyfile keyfile. The unlocked volumes be
A', B' and C' with the uuids AAAA, BBBB
and CCCC. keyfile is saved on C' as
/keyfile.
One luks keyslot of each A, B and C is setup
with a passphrase. Another luks keyslot of each A and B is
setup with keyfile.
To boot this configuration you could use:
rd.luks.uuid=aaaa
rd.luks.uuid=bbbb
rd.luks.uuid=keysource:cccc
rd.luks.key=/keyfile:UUID=CCCC
Dracut asks for the passphrase for C and uses the keyfile
to unlock A and B. If getting the passphrase for C
fails it falls back to asking for the passphrases for A and
B.
If you want C' to stay unlocked, specify a luks name for
it, e.g. rd.luks.name=cccc=mykeys, otherwise it gets closed when not needed
anymore.
rd.luks.key.tout=0
specify how many times dracut will try to read the keys
specified in in rd.luk.key. This gives a chance to the removable device
containing the key to initialise.
MD RAID¶
rd.md=0
disable MD RAID detection
rd.md.imsm=0
disable MD RAID for imsm/isw raids, use DM RAID
instead
rd.md.ddf=0
disable MD RAID for SNIA ddf raids, use DM RAID
instead
rd.md.conf=0
ignore mdadm.conf included in initramfs
rd.md.waitclean=1
wait for any resync, recovery, or reshape activity to
finish before continuing
rd.md.uuid=<md raid uuid>
only activate the raid sets with the given UUID. This
parameter can be specified multiple times.
DM RAID¶
rd.dm=0
disable DM RAID detection
rd.dm.uuid=<dm raid uuid>
only activate the raid sets with the given UUID. This
parameter can be specified multiple times.
MULTIPATH¶
rd.multipath=0
disable multipath detection
rd.multipath=default
use default multipath settings
FIPS¶
rd.fips
enable FIPS
boot=<boot device>
specify the device, where /boot is located.
Example.
boot=/dev/sda1
boot=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
boot=UUID=<uuid>
boot=LABEL=<label>
rd.fips.skipkernel
skip checksum check of the kernel image. Useful, if the
kernel image is not in a separate boot partition.
Network¶
Important
It is recommended to either bind an interface to a MAC with the
ifname argument, or to use the systemd-udevd predictable network
interface names.
Predictable network interface device names based on:
•firmware/bios-provided index numbers for on-board
devices
•firmware-provided pci-express hotplug slot index
number
•physical/geographical location of the
hardware
•the interface’s MAC address
See:
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
Two character prefixes based on the type of interface:
en
ethernet
wl
wlan
ww
wwan
Type of names:
o<index>
on-board device index number
s<slot>[f<function>][d<dev_id>]
hotplug slot index number
x<MAC>
MAC address
[P<domain>]p<bus>s<slot>[f<function>][d<dev_id>]
PCI geographical location
[P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]
USB port number chain
All multi-function PCI devices will carry the [f<function>]
number in the device name, including the function 0 device.
When using PCI geography, The PCI domain is only prepended when it
is not 0.
For USB devices the full chain of port numbers of hubs is
composed. If the name gets longer than the maximum number of 15 characters,
the name is not exported. The usual USB configuration == 1 and interface ==
0 values are suppressed.
PCI ethernet card with firmware index "1"
PCI ethernet card in hotplug slot with firmware index number
PCI ethernet multi-function card with 2 ports
PCI wlan card
USB built-in 3G modem
USB Android phone
The following options are supported by the network-legacy
dracut module. Other network modules might support a slightly different set
of options; refer to the documentation of the specific network module in
use. For NetworkManager, see nm-initrd-generator(8).
ip={dhcp|on|any|dhcp6|auto6|either6|link6|single-dhcp}
dhcp|on|any
get ip from dhcp server from all interfaces. If
netroot=dhcp, loop sequentially through all interfaces (eth0, eth1, ...) and
use the first with a valid DHCP root-path.
single-dhcp
Send DHCP on all available interfaces in parallel, as
opposed to one after another. After the first DHCP response is received, stop
DHCP on all other interfaces. This gives the fastest boot time by using the IP
on interface for which DHCP succeeded first during early boot. Caveat: Does
not apply to Network Manager and to SUSE using wicked.
auto6
IPv6 autoconfiguration
dhcp6
IPv6 DHCP
either6
if auto6 fails, then dhcp6
link6
bring up interface for IPv6 link-local addressing
ip=<interface>:{dhcp|on|any|dhcp6|auto6|link6}[:[<mtu>][:<macaddr>]]
This parameter can be specified multiple times.
dhcp|on|any|dhcp6
get ip from dhcp server on a specific interface
auto6
do IPv6 autoconfiguration
link6
bring up interface for IPv6 link local address
<macaddr>
optionally set <macaddr> on the
<interface>. This cannot be used in conjunction with the ifname
argument for the same <interface>.
ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<mtu>][:<macaddr>]]
explicit network configuration. If you want do define a
IPv6 address, put it in brackets (e.g. [2001:DB8::1]). This parameter can be
specified multiple times.
<peer> is optional and is the address
of the remote endpoint for pointopoint interfaces and it may be followed by a
slash and a decimal number, encoding the network prefix length.
<macaddr>
optionally set <macaddr> on the
<interface>. This cannot be used in conjunction with the ifname
argument for the same <interface>.
ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<dns1>][:<dns2>]]
explicit network configuration. If you want do define a
IPv6 address, put it in brackets (e.g. [2001:DB8::1]). This parameter can be
specified multiple times. <peer> is optional and is the address
of the remote endpoint for pointopoint interfaces and it may be followed by a
slash and a decimal number, encoding the network prefix length.
ifname=<interface>:<MAC>
Assign network device name <interface> (i.e.
"bootnet") to the NIC with MAC <MAC>.
Warning
Do
not use the default kernel naming scheme for the interface name, as it
can conflict with the kernel names. So, don’t use "eth[0-9]+"
for the interface name. Better name it "bootnet" or
"bluesocket".
rd.route=<net>/<netmask>:<gateway>[:<interface>]
Add a static route with route options, which are
separated by a colon. IPv6 addresses have to be put in brackets.
Example.
rd.route=192.168.200.0/24:192.168.100.222:ens10
rd.route=192.168.200.0/24:192.168.100.222
rd.route=192.168.200.0/24::ens10
rd.route=[2001:DB8:3::/8]:[2001:DB8:2::1]:ens10
bootdev=<interface>
specify network interface to use routing and netroot
information from. Required if multiple ip= lines are used.
BOOTIF=<MAC>
specify network interface to use routing and netroot
information from.
rd.bootif=0
Disable BOOTIF parsing, which is provided by PXE
nameserver=<IP>
[nameserver=<IP> ...]
specify nameserver(s) to use
rd.peerdns=0
Disable DNS setting of DHCP parameters.
biosdevname=0
boolean, turn off biosdevname network interface
renaming
rd.neednet=1
boolean, bring up network even without netroot set
vlan=<vlanname>:<phydevice>
Setup vlan device named <vlanname> on
<phydevice>. We support the four styles of vlan names: VLAN_PLUS_VID
(vlan0005), VLAN_PLUS_VID_NO_PAD (vlan5), DEV_PLUS_VID (eth0.0005),
DEV_PLUS_VID_NO_PAD (eth0.5)
bond=<bondname>[:<bondslaves>:[:<options>[:<mtu>]]]
Setup bonding device <bondname> on top of
<bondslaves>. <bondslaves> is a comma-separated list of physical
(ethernet) interfaces. <options> is a comma-separated list on bonding
options (modinfo bonding for details) in format compatible with initscripts.
If <options> includes multi-valued arp_ip_target option, then its values
should be separated by semicolon. if the mtu is specified, it will be set on
the bond master. Bond without parameters assumes
bond=bond0:eth0,eth1:mode=balance-rr
team=<teammaster>:<teamslaves>[:<teamrunner>]
Setup team device <teammaster> on top of
<teamslaves>. <teamslaves> is a comma-separated list of physical
(ethernet) interfaces. <teamrunner> is the runner type to be used (see
teamd.conf(5)); defaults to activebackup. Team without parameters
assumes team=team0:eth0,eth1:activebackup
bridge=<bridgename>:<ethnames>
Setup bridge <bridgename> with <ethnames>.
<ethnames> is a comma-separated list of physical (ethernet) interfaces.
Bridge without parameters assumes bridge=br0:eth0
NFS¶
root=[<server-ip>:]<root-dir>[:<nfs-options>]
mount nfs share from <server-ip>:/<root-dir>,
if no server-ip is given, use dhcp next_server. If server-ip is an IPv6
address it has to be put in brackets, e.g. [2001:DB8::1]. NFS options can be
appended with the prefix ":" or "," and are separated by
",".
root=nfs:[<server-ip>:]<root-dir>[:<nfs-options>],
root=nfs4:[<server-ip>:]<root-dir>[:<nfs-options>],
root={dhcp|dhcp6}
netroot=dhcp alone directs initrd to look at the DHCP
root-path where NFS options can be specified.
Example.
root-path=<server-ip>:<root-dir>[,<nfs-options>]
root-path=nfs:<server-ip>:<root-dir>[,<nfs-options>]
root-path=nfs4:<server-ip>:<root-dir>[,<nfs-options>]
root=/dev/nfs
nfsroot=[<server-ip>:]<root-dir>[:<nfs-options>]
Deprecated! kernel
Documentation_/filesystems/nfsroot.txt_ defines this method. This is supported
by dracut, but not recommended.
rd.nfs.domain=<NFSv4 domain name>
Set the NFSv4 domain name. Will override the settings in
/etc/idmap.conf.
rd.net.dhcp.retry=<cnt>
If this option is set, dracut will try to connect via
dhcp <cnt> times before failing. Default is 1.
rd.net.timeout.dhcp=<arg>
If this option is set, dhclient is called with
"--timeout <arg>".
rd.net.timeout.iflink=<seconds>
Wait <seconds> until link shows up. Default is 60
seconds.
rd.net.timeout.ifup=<seconds>
Wait <seconds> until link has state "UP".
Default is 20 seconds.
rd.net.timeout.route=<seconds>
Wait <seconds> until route shows up. Default is 20
seconds.
rd.net.timeout.ipv6dad=<seconds>
Wait <seconds> until IPv6 DAD is finished. Default
is 50 seconds.
rd.net.timeout.ipv6auto=<seconds>
Wait <seconds> until IPv6 automatic addresses are
assigned. Default is 40 seconds.
rd.net.timeout.carrier=<seconds>
Wait <seconds> until carrier is recognized. Default
is 10 seconds.
CIFS¶
root=cifs://[<username>[:<password>]@]<server-ip>:<root-dir>
mount cifs share from
<server-ip>:/<root-dir>, if no server-ip is given, use dhcp
next_server. if server-ip is an IPv6 address it has to be put in brackets,
e.g. [2001:DB8::1]. If a username or password are not specified as part of the
root, then they must be passed on the command line through cifsuser/cifspass.
Warning
Passwords specified on the kernel command line are visible for all users via the
file
/proc/cmdline and via dmesg or can be sniffed on the network, when
using DHCP with DHCP root-path.
cifsuser=<username>
Set the cifs username, if not specified as part of the
root.
cifspass=<password>
Set the cifs password, if not specified as part of the
root.
Warning
Passwords specified on the kernel command line are visible for all users via the
file
/proc/cmdline and via dmesg or can be sniffed on the network, when
using DHCP with DHCP root-path.
iSCSI¶
root=iscsi:[<username>:<password>[:<reverse>:<password>]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<LUN>]:<targetname>
protocol defaults to "6", LUN defaults to
"0". If the "servername" field is provided by BOOTP or
DHCP, then that field is used in conjunction with other associated fields to
contact the boot server in the Boot stage. However, if the
"servername" field is not provided, then the "targetname"
field is then used in the Discovery Service stage in conjunction with other
associated fields. See
rfc4173[1].
Warning
Passwords specified on the kernel command line are visible for all users via the
file
/proc/cmdline and via dmesg or can be sniffed on the network, when
using DHCP with DHCP root-path.
Example.
root=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
If servername is an IPv6 address, it has to be put in
brackets:
Example.
root=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
root=???
netroot=iscsi:[<username>:<password>[:<reverse>:<password>]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<LUN>]:<targetname>
...
multiple netroot options allow setting up multiple iscsi
disks:
Example.
root=UUID=12424547
netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target1
If servername is an IPv6 address, it has to be put in
brackets:
Example.
netroot=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
Warning
Passwords specified on the kernel command line are visible for all users via the
file
/proc/cmdline and via dmesg or can be sniffed on the network, when
using DHCP with DHCP root-path. You may want to use rd.iscsi.firmware.
root=???
rd.iscsi.initiator=<initiator>
rd.iscsi.target.name=<target name>
rd.iscsi.target.ip=<target ip>
rd.iscsi.target.port=<target port>
rd.iscsi.target.group=<target group>
rd.iscsi.username=<username>
rd.iscsi.password=<password>
rd.iscsi.in.username=<in username>
rd.iscsi.in.password=<in password>
manually specify all iscsistart parameter (see
iscsistart --help)
Warning
Passwords specified on the kernel command line are visible for all users via the
file
/proc/cmdline and via dmesg or can be sniffed on the network, when
using DHCP with DHCP root-path. You may want to use rd.iscsi.firmware.
root=??? netroot=iscsi
rd.iscsi.firmware=1
will read the iscsi parameter from the BIOS
firmware
rd.iscsi.login_retry_max=<num>
maximum number of login retries
rd.iscsi.param=<param>
<param> will be passed as "--param
<param>" to iscsistart. This parameter can be specified multiple
times.
Example.
"netroot=iscsi rd.iscsi.firmware=1 rd.iscsi.param=node.session.timeo.replacement_timeout=30"
will result in
iscsistart -b --param node.session.timeo.replacement_timeout=30
rd.iscsi.ibft rd.iscsi.ibft=1: Turn on iBFT
autoconfiguration for the interfaces
rd.iscsi.mp rd.iscsi.mp=1: Configure all iBFT
interfaces, not only used for booting (multipath)
rd.iscsi.waitnet=0: Turn off waiting for all interfaces to
be up before trying to login to the iSCSI targets.
rd.iscsi.testroute=0: Turn off checking, if the route to
the iSCSI target IP is possible before trying to login.
FCoE¶
rd.fcoe=0
disable FCoE and lldpad
fcoe=<edd|interface|MAC>:{dcb|nodcb}:{fabric|vn2vn}
Try to connect to a FCoE SAN through the NIC specified by
<interface> or
<MAC> or EDD settings. The second
argument specifies if DCB should be used. The optional third argument
specifies whether fabric or VN2VN mode should be used. This parameter can be
specified multiple times.
Note
letters in the MAC-address must be lowercase!
NVMf¶
rd.nonvmf
Disable NVMf
rd.nvmf.hostnqn=<hostNQN>
NVMe host NQN to use
rd.nvmf.hostid=<hostID>
NVMe host id to use
rd.nvmf.discover={rdma|fc|tcp},<traddr>,[<host_traddr>],[<trsvcid>]
Discover and connect to a NVMe-over-Fabric controller
specified by
<traddr> and the optionally
<host_traddr> or
<trsvcid>. The first argument
specifies the transport to use; currently only
rdma,
fc, or
tcp are supported. This parameter can be specified multiple times.
Examples.
rd.nvmf.discover=tcp,192.168.10.10,,4420
rd.nvmf.discover=fc,nn-0x201700a05634f5bf:pn-0x201900a05634f5bf,nn-0x200000109b579ef3:pn-0x100000109b579ef3
rd.nvmf.discover=fc,auto
This special syntax determines that Fibre Channel
autodiscovery is to be used rather than regular NVMe discovery. It takes
precedence over all other rd.nvmf.discover= arguments.
NBD¶
root=???
netroot=nbd:<server>:<port/exportname>[:<fstype>[:<mountopts>[:<nbdopts>]]]
mount nbd share from <server>.
NOTE: If "exportname" instead of "port" is
given the standard port is used. Newer versions of nbd are only supported
with "exportname".
root=/dev/root netroot=dhcp with dhcp
root-path=nbd:<server>:<port/exportname>[:<fstype>[:<mountopts>[:<nbdopts>]]]
netroot=dhcp alone directs initrd to look at the DHCP
root-path where NBD options can be specified. This syntax is only usable in
cases where you are directly mounting the volume as the rootfs.
NOTE: If "exportname" instead of "port" is
given the standard port is used. Newer versions of nbd are only supported
with "exportname".
VIRTIOFS¶
root=virtiofs:<mount-tag>
mount virtiofs share using the tag <mount-tag>. The
tag name is arbitrary and must match the tag given in the qemu -device
command.
rootfstype=virtiofs
root=<mount-tag>
mount virtiofs share using the tag <mount-tag>. The
tag name is arbitrary and must match the tag given in the qemu -device
command.
Both formats are supported by the virtiofs dracut module.
See https://gitlab.com/virtio-fs/virtiofsd for more information.
Example.
DASD¶
rd.dasd=....
same syntax as the kernel module parameter (s390
only)
ZFCP¶
rd.zfcp=<zfcp adaptor device bus
ID>,<WWPN>,<FCPLUN>
rd.zfcp can be specified multiple times on the kernel
command line.
rd.zfcp=<zfcp adaptor device bus ID>
If NPIV is enabled and the
allow_lun_scan
parameter to the zfcp module is set to
Y then the zfcp adaptor will be
initiating a scan internally and the <WWPN> and <FCPLUN>
parameters can be omitted.
Example.
rd.zfcp=0.0.4000,0x5005076300C213e9,0x5022000000000000
rd.zfcp=0.0.4000
rd.zfcp.conf=0
ignore zfcp.conf included in the initramfs
ZNET¶
rd.znet=<nettype>,<subchannels>,<options>
The whole parameter is appended to /etc/ccw.conf, which
is used on RHEL/Fedora with ccw_init, which is called from udev for certain
devices on z-series. rd.znet can be specified multiple times on the kernel
command line.
rd.znet_ifname=<ifname>:<subchannels>
Assign network device name <interface> (i.e.
"bootnet") to the NIC corresponds to the subchannels. This is useful
when dracut’s default "ifname=" doesn’t work due to
device having a changing MAC address.
Example.
rd.znet=qeth,0.0.0600,0.0.0601,0.0.0602,layer2=1,portname=foo
rd.znet=ctc,0.0.0600,0.0.0601,protocol=bar
Booting live images¶
Dracut offers multiple options for live booted images:
SquashFS with read-only filesystem image
The system will boot with a read-only filesystem from the
SquashFS and apply a writable Device-mapper snapshot or an OverlayFS overlay
mount for the read-only base filesystem. This method ensures a relatively fast
boot and lower RAM usage. Users
must be careful to avoid writing too
many blocks to a snapshot volume. Once the blocks of the snapshot overlay are
exhausted, the root filesystem becomes read-only and may cause application
failures. The snapshot overlay file is marked
Overflow, and a difficult
recovery is required to repair and enlarge the overlay offline. Non-persistent
overlays are sparse files in RAM that only consume content space as required
blocks are allocated. They default to an apparent size of 32 GiB in RAM. The
size can be adjusted with the
rd.live.overlay.size= kernel command line
option.
The filesystem structure is traditionally expected to be:
squashfs.img | SquashFS from LiveCD .iso
!(mount)
/LiveOS
|- rootfs.img | Filesystem image to mount read-only
!(mount)
/bin | Live filesystem
/boot |
/dev |
... |
For OverlayFS mount overlays, the filesystem structure may also be
a direct compression of the root filesystem:
squashfs.img | SquashFS from LiveCD .iso
!(mount)
/bin | Live filesystem
/boot |
/dev |
... |
Dracut uses one of the overlay methods of live booting by default.
No additional command line options are required other than
root=live:<URL> to specify the location of your squashed
filesystem.
•The compressed SquashFS image can be copied
during boot to RAM at /run/initramfs/squashed.img by using the
rd.live.ram=1 option.
•A device with a persistent overlay can be booted
read-only by using the rd.live.overlay.readonly option on the kernel
command line. This will either cause a temporary, writable overlay to be
stacked over a read-only snapshot of the root filesystem or the OverlayFS
mount will use an additional lower layer with the root filesystem.
Uncompressed live filesystem image
When the live system was installed with the
--skipcompress option of the
livecd-iso-to-disk installation
script for Live USB devices, the root filesystem image,
rootfs.img, is
expanded on installation and no SquashFS is involved during boot.
•If rd.live.ram=1 is used in this
situation, the full, uncompressed root filesystem is copied during boot to
/run/initramfs/rootfs.img in the /run tmpfs.
•If rd.live.overlay=none is provided as a
kernel command line option, a writable, linear Device-mapper target is created
on boot with no overlay.
Writable filesystem image
The system will retrieve a compressed filesystem image,
extract it to /run/initramfs/fsimg/rootfs.img, connect it to a loop device,
create a writable, linear Device-mapper target at /dev/mapper/live-rw, and
mount that as a writable volume at /. More RAM is required during boot but the
live filesystem is easier to manage if it becomes full. Users can make a
filesystem image of any size and that size will be maintained when the system
boots. There is no persistence of root filesystem changes between boots with
this option.
The filesystem structure is expected to be:
rootfs.tgz | Compressed tarball containing filesystem image
!(unpack)
/rootfs.img | Filesystem image at /run/initramfs/fsimg/
!(mount)
/bin | Live filesystem
/boot |
/dev |
... |
To use this boot option, ensure that rd.writable.fsimg=1 is
in your kernel command line and add the root=live:<URL> to
specify the location of your compressed filesystem image tarball or SquashFS
image.
rd.writable.fsimg=1
Enables writable filesystem support. The system will boot
with a fully writable (but non-persistent) filesystem without snapshots
(see notes above about available live boot options). You can use the
rootflags option to set mount options for the live filesystem as well
(see documentation about rootflags in the Standard
section above). This implies that the whole image is copied to RAM before
the boot continues.
Note
There must be enough free RAM available to hold the complete image.
This method is very suitable for diskless boots.
root=live:<url>
Boots a live image retrieved from
<url>.
Requires the dracut
livenet module. Valid handlers:
http, https,
ftp, torrent, tftp.
Examples.
rd.live.debug=1
Enables debug output from the live boot process.
rd.live.dir=<path>
Specifies the directory within the boot device where the
squashfs.img or rootfs.img can be found. By default, this is /LiveOS.
rd.live.squashimg=<filename of SquashFS
image>
Specifies the filename for a SquashFS image of the root
filesystem. By default, this is squashfs.img.
rd.live.ram=1
Copy the complete image to RAM and use this for booting.
This is useful when the image resides on, e.g., a DVD which needs to be
ejected later on.
rd.live.overlay={<devspec>[:{<pathspec>|auto}]|none}
Manage the usage of a permanent overlay.
•<devspec> specifies the path to a
device with a mountable filesystem.
•
<pathspec> is the path to a file
within that filesystem, which shall be used to persist the changes made to the
device specified by the
root=live:<url> option.
The default pathspec, when auto or no
:<pathspec> is given, is
/<rd.live.dir>/overlay-<label>-<uuid>, where
<label> is the device LABEL, and <uuid> is the
device UUID. * none (the word itself) specifies that no overlay will
be used, such as when an uncompressed, writable live root filesystem is
available.
If a persistent overlay is detected at the standard LiveOS
path, the overlay & overlay type detected, whether Device-mapper or
OverlayFS, will be used.
Examples.
rd.live.overlay=/dev/sdb1:persistent-overlay.img
rd.live.overlay=UUID=99440c1f-8daa-41bf-b965-b7240a8996f4
rd.live.overlay.cowfs=[btrfs|ext4|xfs]
Specifies the filesystem to use when formatting the
overlay partition. The default is ext4.
rd.live.overlay.size=<size_MiB>
Specifies a non-persistent Device-mapper overlay size in
MiB. The default is 32768.
rd.live.overlay.readonly=1
This is used to boot with a normally read-write
persistent overlay in a read-only mode. With this option, either an
additional, non-persistent, writable snapshot overlay will be stacked over a
read-only snapshot, /dev/mapper/live-ro, of the base filesystem with the
persistent overlay, or a read-only loop device, in the case of a writable
rootfs.img, or an OverlayFS mount will use the persistent overlay
directory linked at /run/overlayfs-r as an additional lower layer along with
the base root filesystem and apply a transient, writable upper directory
overlay, in order to complete the booted root filesystem.
rd.live.overlay.reset=1
Specifies that a persistent overlay should be reset on
boot. All previous root filesystem changes are vacated by this action.
rd.live.overlay.thin=1
Enables the usage of thin snapshots instead of classic dm
snapshots. The advantage of thin snapshots is that they support discards, and
will free blocks that are not claimed by the filesystem. In this use case,
this means that memory is given back to the kernel when the filesystem does
not claim it anymore.
rd.live.overlay.overlayfs=1
Enables the use of the
OverlayFS kernel module, if
available, to provide a copy-on-write union directory for the root filesystem.
OverlayFS overlays are directories of the files that have changed on the
read-only base (lower) filesystem. The root filesystem is provided through a
special overlay type mount that merges the lower and upper directories. If an
OverlayFS upper directory is not present on the boot device, a tmpfs directory
will be created at /run/overlayfs to provide temporary storage. Persistent
storage can be provided on vfat or msdos formatted devices by supplying the
OverlayFS upper directory within an embedded filesystem that supports the
creation of trusted.* extended attributes and provides a valid d_type in
readdir responses, such as with ext4 and xfs. On non-vfat-formatted devices, a
persistent OverlayFS overlay can extend the available root filesystem storage
up to the capacity of the LiveOS disk device.
If a persistent overlay is detected at the standard LiveOS path,
the overlay & overlay type detected, whether OverlayFS or Device-mapper,
will be used.
The rd.live.overlay.readonly option, which allows a
persistent overlayfs to be mounted read-only through a higher level
transient overlay directory, has been implemented through the multiple lower
layers feature of OverlayFS.
ZIPL¶
rd.zipl=<path to blockdevice>
Update the dracut commandline with the values found in
the
dracut-cmdline.conf file on the given device. The values are merged
into the existing commandline values and the udev events are regenerated.
Example.
rd.zipl=UUID=0fb28157-99e3-4395-adef-da3f7d44835a
CIO_IGNORE¶
rd.cio_accept=<device-ids>
Remove the devices listed in <device-ids> from the
default cio_ignore kernel command-line settings. <device-ids> is a list
of comma-separated CCW device ids. The default for this value is taken from
the
/boot/zipl/active_devices.txt file.
Example.
rd.cio_accept=0.0.0180,0.0.0800,0.0.0801,0.0.0802
Plymouth Boot Splash¶
plymouth.enable=0
disable the plymouth bootsplash completely.
rd.plymouth=0
disable the plymouth bootsplash only for the
initramfs.
Kernel keys¶
masterkey=<kernel master key path name>
Set the path name of the kernel master key.
Example.
masterkey=/etc/keys/kmk-trusted.blob
masterkeytype=<kernel master key type>
Set the type of the kernel master key.
Example.
evmkey=<EVM HMAC key path name>
Set the path name of the EVM HMAC key.
Example.
evmkey=/etc/keys/evm-trusted.blob
evmx509=<EVM X.509 cert path name>
Set the path name of the EVM X.509 certificate.
Example.
evmx509=/etc/keys/x509_evm.der
ecryptfskey=<eCryptfs key path name>
Set the path name of the eCryptfs key.
Example.
ecryptfskey=/etc/keys/ecryptfs-trusted.blob
Deprecated, renamed Options¶
Here is a list of options, which were used in dracut prior to
version 008, and their new replacement.
rdbreak
rd.break
rd.ccw
rd.znet
rd_CCW
rd.znet
rd_DASD_MOD
rd.dasd
rd_DASD
rd.dasd
rdinitdebug rdnetdebug
rd.debug
rd_NO_DM
rd.dm=0
rd_DM_UUID
rd.dm.uuid
rdblacklist
rd.driver.blacklist
rdinsmodpost
rd.driver.post
rdloaddriver
rd.driver.pre
rd_NO_FSTAB
rd.fstab=0
rdinfo
rd.info
check
rd.live.check
rdlivedebug
rd.live.debug
live_dir
rd.live.dir
liveimg
rd.live.image
overlay
rd.live.overlay
readonly_overlay
rd.live.overlay.readonly
reset_overlay
rd.live.overlay.reset
live_ram
rd.live.ram
rd_NO_CRYPTTAB
rd.luks.crypttab=0
rd_LUKS_KEYDEV_UUID
rd.luks.keydev.uuid
rd_LUKS_KEYPATH
rd.luks.keypath
rd_NO_LUKS
rd.luks=0
rd_LUKS_UUID
rd.luks.uuid
rd_NO_LVMCONF
rd.lvm.conf
rd_LVM_LV
rd.lvm.lv
rd_NO_LVM
rd.lvm=0
rd_LVM_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.
