1DRACUT.CMDLINE(7) dracut DRACUT.CMDLINE(7)
2
6 dracut.cmdline - dracut kernel command line options
7
9 The root device used by the kernel is specified in the boot
10 configuration file on the kernel command line, as always.
11 The traditional root=/dev/sda1 style device specification is allowed,
13 but not encouraged. The root device should better be identified by
14 LABEL or UUID. If a label is used, as in root=LABEL=<label_of_root> the
15 initramfs will search all available devices for a filesystem with the
16 appropriate label, and mount that device as the root filesystem.
17 root=UUID=<uuidnumber> will mount the partition with that UUID as the
18 root filesystem.
19 In the following all kernel command line parameters, which are
21 processed by dracut, are described.
22 "rd.*" parameters mentioned without "=" are boolean parameters. They
24 can be turned on/off by setting them to {0|1}. If the assignment with
25 "=" is missing "=1" is implied. For example rd.info can be turned off
26 with rd.info=0 or turned on with rd.info=1 or rd.info. The last value
27 in the kernel command line is the value, which is honored.
28 Standard
30 init=<path to real init>
31 specify the path to the init program to be started after the
32 initramfs has finished
33 root=<path to blockdevice>
35 specify the block device to use as the root filesystem.
36 Example.
38 root=/dev/sda1
40 root=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
41 root=/dev/disk/by-label/Root
42 root=LABEL=Root
43 root=/dev/disk/by-uuid/3f5ad593-4546-4a94-a374-bcfb68aa11f7
44 root=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
45 root=PARTUUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
46 rootfstype=<filesystem type>
49 "auto" if not specified.
50 Example.
52 rootfstype=ext3
54 rootflags=<mount options>
57 specify additional mount options for the root filesystem. If not
58 set, /etc/fstab of the real root will be parsed for special mount
59 options and mounted accordingly.
60 ro
62 force mounting / and /usr (if it is a separate device) read-only.
63 If none of ro and rw is present, both are mounted according to
64 /etc/fstab.
65 rw
67 force mounting / and /usr (if it is a separate device) read-write.
68 See also ro option.
69 rootfallback=<path to blockdevice>
71 specify the block device to use as the root filesystem, if the
72 normal root cannot be found. This can only be a simple block device
73 with a simple file system, for which the filesystem driver is
74 either compiled in, or added manually to the initramfs. This
75 parameter can be specified multiple times.
76 rd.auto rd.auto=1
78 enable autoassembly of special devices like cryptoLUKS, dmraid,
79 mdraid or lvm. Default is off as of dracut version >= 024.
80 rd.hostonly=0
82 removes all compiled in configuration of the host system the
83 initramfs image was built on. This helps booting, if any disk
84 layout changed, especially in combination with rd.auto or other
85 parameters specifying the layout.
86 rd.cmdline=ask
88 prompts the user for additional kernel command line parameters
89 rd.fstab=0
91 do not honor special mount options for the root filesystem found in
92 /etc/fstab of the real root.
93 resume=<path to resume partition>
95 resume from a swap partition
96 Example.
98 resume=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
100 resume=/dev/disk/by-uuid/3f5ad593-4546-4a94-a374-bcfb68aa11f7
101 resume=UUID=3f5ad593-4546-4a94-a374-bcfb68aa11f7
102 rd.skipfsck
105 skip fsck for rootfs and /usr. If you’re mounting /usr read-only
106 and the init system performs fsck before remount, you might want to
107 use this option to avoid duplication.
108 iso-scan/filename
110 Using iso-scan/filename with a Fedora/Red Hat/CentOS Live iso should
111 just work by copying the original kernel cmdline parameters.
112 Example.
114 menuentry 'Live Fedora 20' --class fedora --class gnu-linux --class gnu --class os {
116 set isolabel=Fedora-Live-LXDE-x86_64-20-1
117 set isofile="/boot/iso/Fedora-Live-LXDE-x86_64-20-1.iso"
118 loopback loop $isofile
119 linux (loop)/isolinux/vmlinuz0 boot=isolinux iso-scan/filename=$isofile root=live:LABEL=$isolabel ro rd.live.image quiet rhgb
120 initrd (loop)/isolinux/initrd0.img
121 }
122 Misc
125 rd.emergency=[reboot|poweroff|halt]
126 specify, what action to execute in case of a critical failure.
127 rd.shell=0 also be specified.
128 rd.driver.blacklist=<drivername>[,<drivername>,...]
130 do not load kernel module <drivername>. This parameter can be
131 specified multiple times.
132 rd.driver.pre=<drivername>[,<drivername>,...]
134 force loading kernel module <drivername>. This parameter can be
135 specified multiple times.
136 rd.driver.post=<drivername>[,<drivername>,...]
138 force loading kernel module <drivername> after all automatic
139 loading modules have been loaded. This parameter can be specified
140 multiple times.
141 rd.retry=<seconds>
143 specify how long dracut should retry the initqueue to configure
144 devices. The default is 30 seconds. After 2/3 of the time, degraded
145 raids are force started. If you have hardware, which takes a very
146 long time to announce its drives, you might want to extend this
147 value.
148 rd.timeout=<seconds>
150 specify how long dracut should wait for devices to appear. The
151 default is 0, which means forever. Note that this timeout should be
152 longer than rd.retry to allow for proper configuration.
153 rd.noverifyssl
155 accept self-signed certificates for ssl downloads.
156 rd.ctty=<terminal device>
158 specify the controlling terminal for the console. This is useful,
159 if you have multiple "console=" arguments.
160 Debug
162 If you are dropped to an emergency shell, the file
163 /run/initramfs/rdsosreport.txt is created, which can be saved to a (to
164 be mounted by hand) partition (usually /boot) or a USB stick.
165 Additional debugging info can be produced by adding rd.debug to the
166 kernel command line. /run/initramfs/rdsosreport.txt contains all logs
167 and the output of some tools. It should be attached to any report about
168 dracut problems.
169 rd.info
171 print informational output though "quiet" is set
172 rd.shell
174 allow dropping to a shell, if root mounting fails
175 rd.debug
177 set -x for the dracut shell. If systemd is active in the initramfs,
178 all output is logged to the systemd journal, which you can inspect
179 with "journalctl -ab". If systemd is not active, the logs are
180 written to dmesg and /run/initramfs/init.log. If "quiet" is set, it
181 also logs to the console.
182 rd.memdebug=[0-4]
184 Print memory usage info at various points, set the verbose level
185 from 0 to 4.
186 Higher level means more debugging output:
188 0 - no output
190 1 - partial /proc/meminfo
191 2 - /proc/meminfo
192 3 - /proc/meminfo + /proc/slabinfo
193 4 - /proc/meminfo + /proc/slabinfo + tracekomem
194 NOTE: tracekomem is a shell script utilizing kernel trace to track
195 the rough total memory consumption of kernel modules during
196 loading. It may override other trace configurations.
197 rd.break
199 drop to a shell at the end
200 rd.break={cmdline|pre-udev|pre-trigger|initqueue|pre-mount|mount|pre-pivot|cleanup}
202 drop to a shell on defined breakpoint
203 rd.udev.info
205 set udev to loglevel info
206 rd.udev.debug
208 set udev to loglevel debug
209 I18N
211 rd.vconsole.keymap=<keymap base file name>
212 keyboard translation table loaded by loadkeys; taken from keymaps
213 directory; will be written as KEYMAP to /etc/vconsole.conf in the
214 initramfs.
215 Example.
217 rd.vconsole.keymap=de-latin1-nodeadkeys
219 rd.vconsole.keymap.ext=<list of keymap base file names>
222 list of extra keymaps to bo loaded (sep. by space); will be written
223 as EXT_KEYMAP to /etc/vconsole.conf in the initramfs
224 rd.vconsole.unicode
226 boolean, indicating UTF-8 mode; will be written as UNICODE to
227 /etc/vconsole.conf in the initramfs
228 rd.vconsole.font=<font base file name>
230 console font; taken from consolefonts directory; will be written as
231 FONT to /etc/vconsole.conf in the initramfs.
232 Example.
234 rd.vconsole.font=eurlatgr
236 rd.vconsole.font.map=<console map base file name>
239 see description of -m parameter in setfont manual; taken from
240 consoletrans directory; will be written as FONT_MAP to
241 /etc/vconsole.conf in the initramfs
242 rd.vconsole.font.unimap=<unicode table base file name>
244 see description of -u parameter in setfont manual; taken from
245 unimaps directory; will be written as FONT_UNIMAP to
246 /etc/vconsole.conf in the initramfs
247 rd.locale.LANG=<locale>
249 taken from the environment; if no UNICODE is defined we set its
250 value in basis of LANG value (whether it ends with ".utf8" (or
251 similar) or not); will be written as LANG to /etc/locale.conf in
252 the initramfs.
253 Example.
255 rd.locale.LANG=pl_PL.utf8
257 rd.locale.LC_ALL=<locale>
260 taken from the environment; will be written as LC_ALL to
261 /etc/locale.conf in the initramfs
262 LVM
264 rd.lvm=0
265 disable LVM detection
266 rd.lvm.vg=<volume group name>
268 only activate the volume groups with the given name. rd.lvm.vg can
269 be specified multiple times on the kernel command line.
270 rd.lvm.lv=<logical volume name>
272 only activate the logical volumes with the given name. rd.lvm.lv
273 can be specified multiple times on the kernel command line.
274 rd.lvm.conf=0
276 remove any /etc/lvm/lvm.conf, which may exist in the initramfs
277 crypto LUKS
279 rd.luks=0
280 disable crypto LUKS detection
281 rd.luks.uuid=<luks uuid>
283 only activate the LUKS partitions with the given UUID. Any "luks-"
284 of the LUKS UUID is removed before comparing to <luks uuid>. The
285 comparisons also matches, if <luks uuid> is only the beginning of
286 the LUKS UUID, so you don’t have to specify the full UUID. This
287 parameter can be specified multiple times.
288 rd.luks.allow-discards=<luks uuid>
290 Allow using of discards (TRIM) requests for LUKS partitions with
291 the given UUID. Any "luks-" of the LUKS UUID is removed before
292 comparing to <luks uuid>. The comparisons also matches, if <luks
293 uuid> is only the beginning of the LUKS UUID, so you don’t have to
294 specify the full UUID. This parameter can be specified multiple
295 times.
296 rd.luks.allow-discards
298 Allow using of discards (TRIM) requests on all LUKS partitions.
299 rd.luks.crypttab=0
301 do not check, if LUKS partition is in /etc/crypttab
302 rd.luks.timeout=<seconds>
304 specify how long dracut should wait when waiting for the user to
305 enter the password. This avoid blocking the boot if no password is
306 entered. It does not apply to luks key. The default is 0, which
307 means forever.
308 crypto LUKS - key on removable device support
310 NB: If systemd is included in the dracut initrd, dracut’s built in
311 removable device keying support won’t work. systemd will prompt for a
312 password from the console even if you’ve supplied rd.luks.key. You may
313 be able to use standard systemd fstab(5) syntax to get the same effect.
314 If you do need rd.luks.key to work, you will have to exclude the
315 "systemd" dracut module and any modules that depend on it. See
316 dracut.conf(5) and https://bugzilla.redhat.com/show_bug.cgi?id=905683
317 for more information.
318 rd.luks.key=<keypath>[:<keydev>[:<luksdev>]]
320 <keypath> is the pathname of a key file, relative to the root of
321 the filesystem on some device. It’s REQUIRED. When <keypath> ends
322 with .gpg it’s considered to be key encrypted symmetrically with
323 GPG. You will be prompted for the GPG password on boot. GPG support
324 comes with the crypt-gpg module, which needs to be added
325 explicitly.
326 <keydev> identifies the device on which the key file resides. It
328 may be the kernel name of the device (should start with "/dev/"), a
329 UUID (prefixed with "UUID=") or a label (prefix with "LABEL="). You
330 don’t have to specify a full UUID. Just its beginning will suffice,
331 even if its ambiguous. All matching devices will be probed. This
332 parameter is recommended, but not required. If it’s not present,
333 all block devices will be probed, which may significantly increase
334 boot time.
335 If <luksdev> is given, the specified key will only be used for the
337 specified LUKS device. Possible values are the same as for
338 <keydev>. Unless you have several LUKS devices, you don’t have to
339 specify this parameter. The simplest usage is:
340 Example.
342 rd.luks.key=/foo/bar.key
344 As you see, you can skip colons in such a case.
347 Note
349 Your LUKS partition must match your key file.
350 dracut provides keys to cryptsetup with -d (an older alias for
352 --key-file). This uses the entire binary content of the key file as
353 part of the secret. If you pipe a password into cryptsetup without
354 -d or --key-file, it will be treated as text user input, and only
355 characters before the first newline will be used. Therefore, when
356 you’re creating an encrypted partition for dracut to mount, and you
357 pipe a key into cryptsetup luksFormat,you must use -d -.
358 Here is an example for a key encrypted with GPG (warning:
360 --batch-mode will overwrite the device without asking for
361 confirmation):
362 gpg --quiet --decrypt rootkey.gpg | \
364 cryptsetup --batch-mode --key-file - \
365 luksFormat /dev/sda47
366 If you use unencrypted key files, just use the key file pathname
368 instead of the standard input. For a random key with 256 bits of
369 entropy, you might use:
370 head -32c /dev/urandom > rootkey.key
372 cryptsetup --batch-mode --key-file rootkey.key \
373 luksFormat /dev/sda47
374 MD RAID
376 rd.md=0
377 disable MD RAID detection
378 rd.md.imsm=0
380 disable MD RAID for imsm/isw raids, use DM RAID instead
381 rd.md.ddf=0
383 disable MD RAID for SNIA ddf raids, use DM RAID instead
384 rd.md.conf=0
386 ignore mdadm.conf included in initramfs
387 rd.md.waitclean=1
389 wait for any resync, recovery, or reshape activity to finish before
390 continuing
391 rd.md.uuid=<md raid uuid>
393 only activate the raid sets with the given UUID. This parameter can
394 be specified multiple times.
395 DM RAID
397 rd.dm=0
398 disable DM RAID detection
399 rd.dm.uuid=<dm raid uuid>
401 only activate the raid sets with the given UUID. This parameter can
402 be specified multiple times.
403 MULTIPATH
405 rd.multipath=0
406 disable multipath detection
407 FIPS
409 rd.fips
410 enable FIPS
411 boot=<boot device>
413 specify the device, where /boot is located.
414 Example.
416 boot=/dev/sda1
418 boot=/dev/disk/by-path/pci-0000:00:1f.1-scsi-0:0:1:0-part1
419 boot=UUID=<uuid>
420 boot=LABEL=<label>
421 rd.fips.skipkernel
424 skip checksum check of the kernel image. Useful, if the kernel
425 image is not in a separate boot partition.
426 Network
428 Important
429 It is recommended to either bind an interface to a MAC with the
430 ifname argument, or to use the systemd-udevd predictable network
431 interface names.
432 Predictable network interface device names based on:
434 · firmware/bios-provided index numbers for on-board devices
436 · firmware-provided pci-express hotplug slot index number
438 · physical/geographical location of the hardware
440 · the interface’s MAC address
442 See:
444 http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames
445 Two character prefixes based on the type of interface:
447 en
449 ethernet
450 wl
452 wlan
453 ww
455 wwan
456 Type of names:
458 o<index>
460 on-board device index number
461 s<slot>[f<function>][d<dev_id>]
463 hotplug slot index number
464 x<MAC>
466 MAC address
467 [P<domain>]p<bus>s<slot>[f<function>][d<dev_id>]
469 PCI geographical location
470 [P<domain>]p<bus>s<slot>[f<function>][u<port>][..][c<config>][i<interface>]
472 USB port number chain
473 All multi-function PCI devices will carry the [f<function>] number
475 in the device name, including the function 0 device.
476 When using PCI geography, The PCI domain is only prepended when it
478 is not 0.
479 For USB devices the full chain of port numbers of hubs is composed.
481 If the name gets longer than the maximum number of 15 characters,
482 the name is not exported. The usual USB configuration == 1 and
483 interface == 0 values are suppressed.
484 PCI ethernet card with firmware index "1"
486 · eno1
488 PCI ethernet card in hotplug slot with firmware index number
490 · ens1
492 PCI ethernet multi-function card with 2 ports
494 · enp2s0f0
496 · enp2s0f1
498 PCI wlan card
500 · wlp3s0
502 USB built-in 3G modem
504 · wwp0s29u1u4i6
506 USB Android phone
508 · enp0s29u1u2
510 ip={dhcp|on|any|dhcp6|auto6|either6}
512 dhcp|on|any
514 get ip from dhcp server from all interfaces. If root=dhcp, loop
515 sequentially through all interfaces (eth0, eth1, ...) and use
516 the first with a valid DHCP root-path.
517 auto6
519 IPv6 autoconfiguration
520 dhcp6
522 IPv6 DHCP
523 either6
525 if auto6 fails, then dhcp6
526 ip=<interface>:{dhcp|on|any|dhcp6|auto6}[:[<mtu>][:<macaddr>]]
528 This parameter can be specified multiple times.
529 dhcp|on|any|dhcp6
531 get ip from dhcp server on a specific interface
532 auto6
534 do IPv6 autoconfiguration
535 <macaddr>
537 optionally set <macaddr> on the <interface>. This cannot be
538 used in conjunction with the ifname argument for the same
539 <interface>.
540 ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<mtu>][:<macaddr>]]
542 explicit network configuration. If you want do define a IPv6
543 address, put it in brackets (e.g. [2001:DB8::1]). This parameter
544 can be specified multiple times. <peer> is optional and is the
545 address of the remote endpoint for pointopoint interfaces and it
546 may be followed by a slash and a decimal number, encoding the
547 network prefix length.
548 <macaddr>
550 optionally set <macaddr> on the <interface>. This cannot be
551 used in conjunction with the ifname argument for the same
552 <interface>.
553 ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<dns1>][:<dns2>]]
555 explicit network configuration. If you want do define a IPv6
556 address, put it in brackets (e.g. [2001:DB8::1]). This parameter
557 can be specified multiple times. <peer> is optional and is the
558 address of the remote endpoint for pointopoint interfaces and it
559 may be followed by a slash and a decimal number, encoding the
560 network prefix length.
561 ifname=<interface>:<MAC>
563 Assign network device name <interface> (i.e. "bootnet") to the NIC
564 with MAC <MAC>.
565 Warning
567 Do not use the default kernel naming scheme for the interface
568 name, as it can conflict with the kernel names. So, don’t use
569 "eth[0-9]+" for the interface name. Better name it "bootnet" or
570 "bluesocket".
571 rd.route=<net>/<netmask>:<gateway>[:<interface>]
573 Add a static route with route options, which are separated by a
574 colon. IPv6 addresses have to be put in brackets.
575 Example.
577 rd.route=192.168.200.0/24:192.168.100.222:ens10
579 rd.route=192.168.200.0/24:192.168.100.222
580 rd.route=192.168.200.0/24::ens10
581 rd.route=[2001:DB8:3::/8]:[2001:DB8:2::1]:ens10
582 bootdev=<interface>
585 specify network interface to use routing and netroot information
586 from. Required if multiple ip= lines are used.
587 BOOTIF=<MAC>
589 specify network interface to use routing and netroot information
590 from.
591 rd.bootif=0
593 Disable BOOTIF parsing, which is provided by PXE
594 nameserver=<IP> [nameserver=<IP> ...]
596 specify nameserver(s) to use
597 rd.peerdns=0
599 Disable DNS setting of DHCP parameters.
600 biosdevname=0
602 boolean, turn off biosdevname network interface renaming
603 rd.neednet=1
605 boolean, bring up network even without netroot set
606 vlan=<vlanname>:<phydevice>
608 Setup vlan device named <vlanname> on <phydeivce>. We support the
609 four styles of vlan names: VLAN_PLUS_VID (vlan0005),
610 VLAN_PLUS_VID_NO_PAD (vlan5), DEV_PLUS_VID (eth0.0005),
611 DEV_PLUS_VID_NO_PAD (eth0.5)
612 bond=<bondname>[:<bondslaves>:[:<options>[:<mtu>]]]
614 Setup bonding device <bondname> on top of <bondslaves>.
615 <bondslaves> is a comma-separated list of physical (ethernet)
616 interfaces. <options> is a comma-separated list on bonding options
617 (modinfo bonding for details) in format compatible with
618 initscripts. If <options> includes multi-valued arp_ip_target
619 option, then its values should be separated by semicolon. if the
620 mtu is specified, it will be set on the bond master. Bond without
621 parameters assumes bond=bond0:eth0,eth1:mode=balance-rr
622 team=<teammaster>:<teamslaves>
624 Setup team device <teammaster> on top of <teamslaves>. <teamslaves>
625 is a comma-separated list of physical (ethernet) interfaces.
626 bridge=<bridgename>:<ethnames>
628 Setup bridge <bridgename> with <ethnames>. <ethnames> is a
629 comma-separated list of physical (ethernet) interfaces. Bridge
630 without parameters assumes bridge=br0:eth0
631 NFS
633 root=[<server-ip>:]<root-dir>[:<nfs-options>]
634 mount nfs share from <server-ip>:/<root-dir>, if no server-ip is
635 given, use dhcp next_server. If server-ip is an IPv6 address it has
636 to be put in brackets, e.g. [2001:DB8::1]. NFS options can be
637 appended with the prefix ":" or "," and are separated by ",".
638 root=nfs:[<server-ip>:]<root-dir>[:<nfs-options>],
640 root=nfs4:[<server-ip>:]<root-dir>[:<nfs-options>], root={dhcp|dhcp6}
641 root=dhcp alone directs initrd to look at the DHCP root-path where
642 NFS options can be specified.
643 Example.
645 root-path=<server-ip>:<root-dir>[,<nfs-options>]
647 root-path=nfs:<server-ip>:<root-dir>[,<nfs-options>]
648 root-path=nfs4:<server-ip>:<root-dir>[,<nfs-options>]
649 root=/dev/nfs nfsroot=[<server-ip>:]<root-dir>[:<nfs-options>]
652 Deprecated! kernel Documentation_/filesystems/nfsroot.txt_ defines
653 this method. This is supported by dracut, but not recommended.
654 rd.nfs.domain=<NFSv4 domain name>
656 Set the NFSv4 domain name. Will override the settings in
657 /etc/idmap.conf.
658 rd.net.dhcp.retry=<cnt>
660 If this option is set, dracut will try to connect via dhcp <cnt>
661 times before failing. Default is 1.
662 rd.net.timeout.dhcp=<arg>
664 If this option is set, dhclient is called with "-timeout <arg>".
665 rd.net.timeout.iflink=<seconds>
667 Wait <seconds> until link shows up. Default is 60 seconds.
668 rd.net.timeout.ifup=<seconds>
670 Wait <seconds> until link has state "UP". Default is 20 seconds.
671 rd.net.timeout.route=<seconds>
673 Wait <seconds> until route shows up. Default is 20 seconds.
674 rd.net.timeout.ipv6dad=<seconds>
676 Wait <seconds> until IPv6 DAD is finished. Default is 50 seconds.
677 rd.net.timeout.ipv6auto=<seconds>
679 Wait <seconds> until IPv6 automatic addresses are assigned. Default
680 is 40 seconds.
681 rd.net.timeout.carrier=<seconds>
683 Wait <seconds> until carrier is recognized. Default is 10 seconds.
684 CIFS
686 root=cifs://[<username>[:<password>]@]<server-ip>:<root-dir>
687 mount cifs share from <server-ip>:/<root-dir>, if no server-ip is
688 given, use dhcp next_server. if server-ip is an IPv6 address it has
689 to be put in brackets, e.g. [2001:DB8::1]. If a username or
690 password are not specified as part of the root, then they must be
691 passed on the command line through cifsuser/cifspass.
692 Warning
694 Passwords specified on the kernel command line are visible for
695 all users via the file /proc/cmdline and via dmesg or can be
696 sniffed on the network, when using DHCP with DHCP root-path.
697 cifsuser=<username>
699 Set the cifs username, if not specified as part of the root.
700 cifspass=<password>
702 Set the cifs password, if not specified as part of the root.
703 Warning
705 Passwords specified on the kernel command line are visible for
706 all users via the file /proc/cmdline and via dmesg or can be
707 sniffed on the network, when using DHCP with DHCP root-path.
708 iSCSI
710 root=iscsi:[<username>:<password>[:<reverse>:<password>]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<LUN>]:<targetname>
711 protocol defaults to "6", LUN defaults to "0". If the "servername"
712 field is provided by BOOTP or DHCP, then that field is used in
713 conjunction with other associated fields to contact the boot server
714 in the Boot stage. However, if the "servername" field is not
715 provided, then the "targetname" field is then used in the Discovery
716 Service stage in conjunction with other associated fields. See
717 rfc4173[1].
718 Warning
720 Passwords specified on the kernel command line are visible for
721 all users via the file /proc/cmdline and via dmesg or can be
722 sniffed on the network, when using DHCP with DHCP root-path.
723 Example.
725 root=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
727 If servername is an IPv6 address, it has to be put in brackets:
730 Example.
732 root=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
734 root=???
737 netroot=iscsi:[<username>:<password>[:<reverse>:<password>]@][<servername>]:[<protocol>]:[<port>][:[<iscsi_iface_name>]:[<netdev_name>]]:[<LUN>]:<targetname>
738 ...
739 multiple netroot options allow setting up multiple iscsi disks:
740 Example.
742 root=UUID=12424547
744 netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target0
745 netroot=iscsi:192.168.50.1::::iqn.2009-06.dracut:target1
746 If servername is an IPv6 address, it has to be put in brackets:
749 Example.
751 netroot=iscsi:[2001:DB8::1]::::iqn.2009-06.dracut:target0
753 Warning
756 Passwords specified on the kernel command line are visible for
757 all users via the file /proc/cmdline and via dmesg or can be
758 sniffed on the network, when using DHCP with DHCP root-path.
759 You may want to use rd.iscsi.firmware.
760 root=??? rd.iscsi.initiator=<initiator> rd.iscsi.target.name=<target
762 name> rd.iscsi.target.ip=<target ip> rd.iscsi.target.port=<target port>
763 rd.iscsi.target.group=<target group> rd.iscsi.username=<username>
764 rd.iscsi.password=<password> rd.iscsi.in.username=<in username>
765 rd.iscsi.in.password=<in password>
766 manually specify all iscsistart parameter (see iscsistart --help)
767 Warning
769 Passwords specified on the kernel command line are visible for
770 all users via the file /proc/cmdline and via dmesg or can be
771 sniffed on the network, when using DHCP with DHCP root-path.
772 You may want to use rd.iscsi.firmware.
773 root=??? netroot=iscsi rd.iscsi.firmware=1
775 will read the iscsi parameter from the BIOS firmware
776 rd.iscsi.login_retry_max=<num>
778 maximum number of login retries
779 rd.iscsi.param=<param>
781 <param> will be passed as "--param <param>" to iscsistart. This
782 parameter can be specified multiple times.
783 Example.
785 "netroot=iscsi rd.iscsi.firmware=1 rd.iscsi.param=node.session.timeo.replacement_timeout=30"
787 will result in
790 iscsistart -b --param node.session.timeo.replacement_timeout=30
792 rd.iscsi.ibft rd.iscsi.ibft=1: Turn on iBFT autoconfiguration for the
794 interfaces
795 rd.iscsi.mp rd.iscsi.mp=1: Configure all iBFT interfaces, not only used
797 for booting (multipath)
798 rd.iscsi.waitnet=0: Turn off waiting for all interfaces to be up before
800 trying to login to the iSCSI targets.
801 rd.iscsi.testroute=0: Turn off checking, if the route to the iSCSI
803 target IP is possible before trying to login.
804 FCoE
806 rd.nofcoe=0
807 disable FCoE and lldpad
808 fcoe=<edd|interface|MAC>:{dcb|nodcb}:{fabric|vn2vn}
810 Try to connect to a FCoE SAN through the NIC specified by
811 <interface> or <MAC> or EDD settings. The second argument specifies
812 if DCB should be used. The optional third argument specifies
813 whether fabric or VN2VN mode should be used. This parameter can be
814 specified multiple times.
815 Note
817 letters in the MAC-address must be lowercase!
818 NBD
820 root=???
821 netroot=nbd:<server>:<port/exportname>[:<fstype>[:<mountopts>[:<nbdopts>]]]
822 mount nbd share from <server>.
823 NOTE: If "exportname" instead of "port" is given the standard port
825 is used. Newer versions of nbd are only supported with
826 "exportname".
827 root=dhcp with dhcp
829 root-path=nbd:<server>:<port/exportname>[:<fstype>[:<mountopts>[:<nbdopts>]]]
830 root=dhcp alone directs initrd to look at the DHCP root-path where
831 NBD options can be specified. This syntax is only usable in cases
832 where you are directly mounting the volume as the rootfs.
833 NOTE: If "exportname" instead of "port" is given the standard port
835 is used. Newer versions of nbd are only supported with
836 "exportname".
837 DASD
839 rd.dasd=....
840 same syntax as the kernel module parameter (s390 only)
841 ZFCP
843 rd.zfcp=<zfcp adaptor device bus ID>,<WWPN>,<FCPLUN>
844 rd.zfcp can be specified multiple times on the kernel command line.
845 rd.zfcp=<zfcp adaptor device bus ID>
847 If NPIV is enabled and the allow_lun_scan parameter to the zfcp
848 module is set to Y then the zfcp adaptor will be initiating a scan
849 internally and the <WWPN> and <FCPLUN> parameters can be omitted.
850 Example.
852 rd.zfcp=0.0.4000,0x5005076300C213e9,0x5022000000000000
854 rd.zfcp=0.0.4000
855 rd.zfcp.conf=0
858 ignore zfcp.conf included in the initramfs
859 ZNET
861 rd.znet=<nettype>,<subchannels>,<options>
862 The whole parameter is appended to /etc/ccw.conf, which is used on
863 RHEL/Fedora with ccw_init, which is called from udev for certain
864 devices on z-series. rd.znet can be specified multiple times on the
865 kernel command line.
866 Example.
868 rd.znet=qeth,0.0.0600,0.0.0601,0.0.0602,layer2=1,portname=foo
870 rd.znet=ctc,0.0.0600,0.0.0601,protocol=bar
871 Booting live images
874 Dracut offers multiple options for live booted images:
875 SquashFS with read-only filesystem image
877 The system will boot with a read-only filesystem from the SquashFS
878 and apply a writable Device-mapper snapshot or an OverlayFS overlay
879 mount for the read-only base filesystem. This method ensures a
880 relatively fast boot and lower RAM usage. Users must be careful to
881 avoid writing too many blocks to a snapshot volume. Once the blocks
882 of the snapshot overlay are exhausted, the root filesystem becomes
883 read-only and may cause application failures. The snapshot overlay
884 file is marked Overflow, and a difficult recovery is required to
885 repair and enlarge the overlay offline. Non-persistent overlays are
886 sparse files in RAM that only consume content space as required
887 blocks are allocated. They default to an apparent size of 32 GiB in
888 RAM. The size can be adjusted with the rd.live.overlay.size= kernel
889 command line option.
890 The filesystem structure is traditionally expected to be:
892 squashfs.img | SquashFS from LiveCD .iso
894 !(mount)
895 /LiveOS
896 |- rootfs.img | Filesystem image to mount read-only
897 !(mount)
898 /bin | Live filesystem
899 /boot |
900 /dev |
901 ... |
902 For OverlayFS mount overlays, the filesystem structure may also be
904 a direct compression of the root filesystem:
905 squashfs.img | SquashFS from LiveCD .iso
907 !(mount)
908 /bin | Live filesystem
909 /boot |
910 /dev |
911 ... |
912 Dracut uses one of the overlay methods of live booting by default.
914 No additional command line options are required other than
915 root=live:<URL> to specify the location of your squashed
916 filesystem.
917 · The compressed SquashFS image can be copied during boot to RAM
919 at /run/initramfs/squashed.img by using the rd.live.ram=1
920 option.
921 · A device with a persistent overlay can be booted read-only by
923 using the rd.live.overlay.readonly option on the kernel command
924 line. This will either cause a temporary, writable overlay to
925 be stacked over a read-only snapshot of the root filesystem or
926 the OverlayFS mount will use an additional lower layer with the
927 root filesystem.
928 Uncompressed live filesystem image
930 When the live system was installed with the --skipcompress option
931 of the livecd-iso-to-disk installation script for Live USB devices,
932 the root filesystem image, rootfs.img, is expanded on installation
933 and no SquashFS is involved during boot.
934 · If rd.live.ram=1 is used in this situation, the full,
936 uncompressed root filesystem is copied during boot to
937 /run/initramfs/rootfs.img in the /run tmpfs.
938 · If rd.live.overlay=none is provided as a kernel command line
940 option, a writable, linear Device-mapper target is created on
941 boot with no overlay.
942 Writable filesystem image
944 The system will retrieve a compressed filesystem image, extract it
945 to /run/initramfs/fsimg/rootfs.img, connect it to a loop device,
946 create a writable, linear Device-mapper target at
947 /dev/mapper/live-rw, and mount that as a writable volume at /. More
948 RAM is required during boot but the live filesystem is easier to
949 manage if it becomes full. Users can make a filesystem image of any
950 size and that size will be maintained when the system boots. There
951 is no persistence of root filesystem changes between boots with
952 this option.
953 The filesystem structure is expected to be:
955 rootfs.tgz | Compressed tarball containing filesystem image
957 !(unpack)
958 /rootfs.img | Filesystem image at /run/initramfs/fsimg/
959 !(mount)
960 /bin | Live filesystem
961 /boot |
962 /dev |
963 ... |
964 To use this boot option, ensure that rd.writable.fsimg=1 is in your
966 kernel command line and add the root=live:<URL> to specify the
967 location of your compressed filesystem image tarball or SquashFS
968 image.
969 rd.writable.fsimg=1
971 Enables writable filesystem support. The system will boot with a
972 fully writable (but non-persistent) filesystem without snapshots
973 (see notes above about available live boot options). You can use
974 the rootflags option to set mount options for the live filesystem
975 as well (see documentation about rootflags in the Standard section
976 above). This implies that the whole image is copied to RAM before
977 the boot continues.
978 Note
980 There must be enough free RAM available to hold the complete
981 image.
982 This method is very suitable for diskless boots.
983 root=live:<url>
985 Boots a live image retrieved from <url>. Requires the dracut
986 livenet module. Valid handlers: http, https, ftp, torrent, tftp.
987 Examples.
989 root=live:http://example.com/liveboot.img
991 root=live:ftp://ftp.example.com/liveboot.img
992 root=live:torrent://example.com/liveboot.img.torrent
993 rd.live.debug=1
996 Enables debug output from the live boot process.
997 rd.live.dir=<path>
999 Specifies the directory within the boot device where the
1000 squashfs.img or rootfs.img can be found. By default, this is
1001 /LiveOS.
1002 rd.live.squashimg=<filename of SquashFS image>
1004 Specifies the filename for a SquashFS image of the root filesystem.
1005 By default, this is squashfs.img.
1006 rd.live.ram=1
1008 Copy the complete image to RAM and use this for booting. This is
1009 useful when the image resides on, e.g., a DVD which needs to be
1010 ejected later on.
1011 rd.live.overlay={<devspec>[:{<pathspec>|auto}]|none}
1013 Manage the usage of a permanent overlay.
1014 · <devspec> specifies the path to a device with a mountable
1016 filesystem.
1017 · <pathspec> is the path to a file within that filesystem, which
1019 shall be used to persist the changes made to the device
1020 specified by the root=live:<url> option.
1021 The default pathspec, when auto or no :<pathspec> is given, is
1023 /<<b>rd.live.dir</b>>/overlay-<label>-<uuid>, where <label> is
1024 the device LABEL, and <uuid> is the device UUID. * none (the
1025 word itself) specifies that no overlay will be used, such as
1026 when an uncompressed, writable live root filesystem is
1027 available.
1028 If a persistent overlay is detected at the standard LiveOS
1030 path, the overlay & overlay type detected, whether
1031 Device-mapper or OverlayFS, will be used.
1032 Examples.
1034 rd.live.overlay=/dev/sdb1:persistent-overlay.img
1036 rd.live.overlay=UUID=99440c1f-8daa-41bf-b965-b7240a8996f4
1037 rd.live.overlay.size=<size_MiB>
1040 Specifies a non-persistent Device-mapper overlay size in MiB. The
1041 default is 32768.
1042 rd.live.overlay.readonly=1
1044 This is used to boot with a normally read-write persistent overlay
1045 in a read-only mode. With this option, either an additional,
1046 non-persistent, writable snapshot overlay will be stacked over a
1047 read-only snapshot, /dev/mapper/live-ro, of the base filesystem
1048 with the persistent overlay, or a read-only loop device, in the
1049 case of a writable rootfs.img, or an OverlayFS mount will use the
1050 persistent overlay directory linked at /run/overlayfs-r as an
1051 additional lower layer along with the base root filesystem and
1052 apply a transient, writable upper directory overlay, in order to
1053 complete the booted root filesystem.
1054 rd.live.overlay.reset=1
1056 Specifies that a persistent overlay should be reset on boot. All
1057 previous root filesystem changes are vacated by this action.
1058 rd.live.overlay.thin=1
1060 Enables the usage of thin snapshots instead of classic dm
1061 snapshots. The advantage of thin snapshots is that they support
1062 discards, and will free blocks that are not claimed by the
1063 filesystem. In this use case, this means that memory is given back
1064 to the kernel when the filesystem does not claim it anymore.
1065 rd.live.overlay.overlayfs=1
1067 Enables the use of the OverlayFS kernel module, if available, to
1068 provide a copy-on-write union directory for the root filesystem.
1069 OverlayFS overlays are directories of the files that have changed
1070 on the read-only base (lower) filesystem. The root filesystem is
1071 provided through a special overlay type mount that merges the lower
1072 and upper directories. If an OverlayFS upper directory is not
1073 present on the boot device, a tmpfs directory will be created at
1074 /run/overlayfs to provide temporary storage. Persistent storage can
1075 be provided on vfat or msdos formatted devices by supplying the
1076 OverlayFS upper directory within an embedded filesystem that
1077 supports the creation of trusted.* extended attributes and provides
1078 a valid d_type in readdir responses, such as with ext4 and xfs. On
1079 non-vfat-formatted devices, a persistent OverlayFS overlay can
1080 extend the available root filesystem storage up to the capacity of
1081 the LiveOS disk device.
1082 If a persistent overlay is detected at the standard LiveOS path,
1084 the overlay & overlay type detected, whether OverlayFS or
1085 Device-mapper, will be used.
1086 The rd.live.overlay.readonly option, which allows a persistent
1088 overlayfs to be mounted read-only through a higher level transient
1089 overlay directory, has been implemented through the multiple lower
1090 layers feature of OverlayFS.
1091 ZIPL
1093 rd.zipl=<path to blockdevice>
1094 Update the dracut commandline with the values found in the
1095 dracut-cmdline.conf file on the given device. The values are merged
1096 into the existing commandline values and the udev events are
1097 regenerated.
1098 Example.
1100 rd.zipl=UUID=0fb28157-99e3-4395-adef-da3f7d44835a
1102 CIO_IGNORE
1105 rd.cio_accept=<device-ids>
1106 Remove the devices listed in <device-ids> from the default
1107 cio_ignore kernel command-line settings. <device-ids> is a list of
1108 comma-separated CCW device ids. The default for this value is taken
1109 from the /boot/zipl/active_devices.txt file.
1110 Example.
1112 rd.cio_accept=0.0.0180,0.0.0800,0.0.0801,0.0.0802
1114 Plymouth Boot Splash
1117 plymouth.enable=0
1118 disable the plymouth bootsplash completely.
1119 rd.plymouth=0
1121 disable the plymouth bootsplash only for the initramfs.
1122 Kernel keys
1124 masterkey=<kernel master key path name>
1125 Set the path name of the kernel master key.
1126 Example.
1128 masterkey=/etc/keys/kmk-trusted.blob
1130 masterkeytype=<kernel master key type>
1133 Set the type of the kernel master key.
1134 Example.
1136 masterkeytype=trusted
1138 evmkey=<EVM key path name>
1141 Set the path name of the EVM key.
1142 Example.
1144 evmkey=/etc/keys/evm-trusted.blob
1146 ecryptfskey=<eCryptfs key path name>
1149 Set the path name of the eCryptfs key.
1150 Example.
1152 ecryptfskey=/etc/keys/ecryptfs-trusted.blob
1154 Deprecated, renamed Options
1157 Here is a list of options, which were used in dracut prior to version
1158 008, and their new replacement.
1159 rdbreak
1161 rd.break
1162 rd.ccw
1164 rd.znet
1165 rd_CCW
1167 rd.znet
1168 rd_DASD_MOD
1170 rd.dasd
1171 rd_DASD
1173 rd.dasd
1174 rdinitdebug rdnetdebug
1176 rd.debug
1177 rd_NO_DM
1179 rd.dm=0
1180 rd_DM_UUID
1182 rd.dm.uuid
1183 rdblacklist
1185 rd.driver.blacklist
1186 rdinsmodpost
1188 rd.driver.post
1189 rdloaddriver
1191 rd.driver.pre
1192 rd_NO_FSTAB
1194 rd.fstab=0
1195 rdinfo
1197 rd.info
1198 check
1200 rd.live.check
1201 rdlivedebug
1203 rd.live.debug
1204 live_dir
1206 rd.live.dir
1207 liveimg
1209 rd.live.image
1210 overlay
1212 rd.live.overlay
1213 readonly_overlay
1215 rd.live.overlay.readonly
1216 reset_overlay
1218 rd.live.overlay.reset
1219 live_ram
1221 rd.live.ram
1222 rd_NO_CRYPTTAB
1224 rd.luks.crypttab=0
1225 rd_LUKS_KEYDEV_UUID
1227 rd.luks.keydev.uuid
1228 rd_LUKS_KEYPATH
1230 rd.luks.keypath
1231 rd_NO_LUKS
1233 rd.luks=0
1234 rd_LUKS_UUID
1236 rd.luks.uuid
1237 rd_NO_LVMCONF
1239 rd.lvm.conf
1240 rd_LVM_LV
1242 rd.lvm.lv
1243 rd_NO_LVM
1245 rd.lvm=0
1246 rd_LVM_SNAPSHOT
1248 rd.lvm.snapshot
1249 rd_LVM_SNAPSIZE
1251 rd.lvm.snapsize
1252 rd_LVM_VG
1254 rd.lvm.vg
1255 rd_NO_MDADMCONF
1257 rd.md.conf=0
1258 rd_NO_MDIMSM
1260 rd.md.imsm=0
1261 rd_NO_MD
1263 rd.md=0
1264 rd_MD_UUID
1266 rd.md.uuid
1267 rd_NO_MULTIPATH: rd.multipath=0
1269 rd_NFS_DOMAIN
1271 rd.nfs.domain
1272 iscsi_initiator
1274 rd.iscsi.initiator
1275 iscsi_target_name
1277 rd.iscsi.target.name
1278 iscsi_target_ip
1280 rd.iscsi.target.ip
1281 iscsi_target_port
1283 rd.iscsi.target.port
1284 iscsi_target_group
1286 rd.iscsi.target.group
1287 iscsi_username
1289 rd.iscsi.username
1290 iscsi_password
1292 rd.iscsi.password
1293 iscsi_in_username
1295 rd.iscsi.in.username
1296 iscsi_in_password
1298 rd.iscsi.in.password
1299 iscsi_firmware
1301 rd.iscsi.firmware=0
1302 rd_NO_PLYMOUTH
1304 rd.plymouth=0
1305 rd_retry
1307 rd.retry
1308 rdshell
1310 rd.shell
1311 rd_NO_SPLASH
1313 rd.splash
1314 rdudevdebug
1316 rd.udev.debug
1317 rdudevinfo
1319 rd.udev.info
1320 rd_NO_ZFCPCONF
1322 rd.zfcp.conf=0
1323 rd_ZFCP
1325 rd.zfcp
1326 rd_ZNET
1328 rd.znet
1329 KEYMAP
1331 vconsole.keymap
1332 KEYTABLE
1334 vconsole.keymap
1335 SYSFONT
1337 vconsole.font
1338 CONTRANS
1340 vconsole.font.map
1341 UNIMAP
1343 vconsole.font.unimap
1344 UNICODE
1346 vconsole.unicode
1347 EXT_KEYMAP
1349 vconsole.keymap.ext
1350 Configuration in the Initramfs
1352 /etc/conf.d/
1353 Any files found in /etc/conf.d/ will be sourced in the initramfs to
1354 set initial values. Command line options will override these values
1355 set in the configuration files.
1356 /etc/cmdline
1358 Can contain additional command line options. Deprecated, better use
1359 /etc/cmdline.d/*.conf.
1360 /etc/cmdline.d/*.conf
1362 Can contain additional command line options.
1363
1365 Harald Hoyer
1366
1368 dracut(8) dracut.conf(5)
1369
1371 1. rfc4173
1372 http://tools.ietf.org/html/rfc4173#section-5
1373dracut 050 03/04/2020 DRACUT.CMDLINE(7)