Standard
~~~~~~~~
**init=**__<path to real init>__::
- specify the path to the init programm to be started after the initramfs has
+ specify the path to the init program to be started after the initramfs has
finished
**root=**__<path to blockdevice>__::
Misc
~~~~
+**rd.emergency=**__[reboot|poweroff|halt]__::
+ specify, what action to execute in case of a critical failure. rd.shell=0 also
+ be specified.
+
**rd.driver.blacklist=**__<drivername>__[,__<drivername>__,...]::
do not load kernel module <drivername>. This parameter can be specified
multiple times.
_/run/initramfs/init.log_.
If "quiet" is set, it also logs to the console.
-**rd.memdebug=[0-3]**::
- Print memory usage info at various points, set the verbose level from 0 to 3.
+**rd.memdebug=[0-4]**::
+ Print memory usage info at various points, set the verbose level from 0 to 4.
+
Higher level means more debugging output:
+
1 - partial /proc/meminfo
2 - /proc/meminfo
3 - /proc/meminfo + /proc/slabinfo
+ 4 - /proc/meminfo + /proc/slabinfo + tracekomem
+ NOTE: tracekomem is a shell script utilizing kernel trace to track
+ the rough total memory consumption of kernel modules during
+ loading. It may override other trace configurations.
----
**rd.break**::
same <interface>.
=====================
-**ip=**__<client-IP>__:[__<peer>__]:__<gateway-IP>__:__<netmask>__:__<client_hostname>__:__<interface>__:__{none|off|dhcp|on|any|dhcp6|auto6|ibft}__:[:[__<mtu>__][:__<macaddr>__]]::
+**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
VLAN_PLUS_VID_NO_PAD (vlan5), DEV_PLUS_VID (eth0.0005),
DEV_PLUS_VID_NO_PAD (eth0.5)
-**bond=**__<bondname>__[:__<bondslaves>__:[:__<options>__]]::
+**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. Bond without parameters assumes
+ 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>__::
method. This is supported by dracut, but not recommended.
**rd.nfs.domain=**__<NFSv4 domain name>__::
- Set the NFSv4 domain name. Will overwrite the settings in _/etc/idmap.conf_.
+ 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.
NBD
~~~
-**root=**??? **netroot=**nbd:__<server>__:__<port>__[:__<fstype>__[:__<mountopts>__[:__<nbdopts>__]]]::
- mount nbd share from <server>
+**root=**??? **netroot=**nbd:__<server>__:__<port/exportname>__[:__<fstype>__[:__<mountopts>__[:__<nbdopts>__]]]::
+ mount nbd share from <server>.
++
+NOTE:
+ If "exportname" instead of "port" is given the standard port is used.
+ Newer versions of nbd are only supported with "exportname".
-**root=dhcp** with **dhcp** **root-path=**nbd:__<server>__:__<port>__[:__<fstype>__[:__<mountopts>__[:__<nbdopts>__]]]::
+**root=dhcp** with **dhcp** **root-path=**nbd:__<server>__:__<port/exportname>__[:__<fstype>__[:__<mountopts>__[:__<nbdopts>__]]]::
root=dhcp alone directs initrd to look at the DHCP root-path where NBD
options can be specified. This syntax is only usable in cases where you are
directly mounting the volume as the rootfs.
++
+NOTE:
+ If "exportname" instead of "port" is given the standard port is used.
+ Newer versions of nbd are only supported with "exportname".
DASD
~~~~
ZFCP
~~~~
**rd.zfcp=**__<zfcp adaptor device bus ID>__,__<WWPN>__,__<FCPLUN>__::
- rd.zfcp can be specified multiple times on the kernel command line.
+ 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.
+
[listing]
.Example
--
rd.zfcp=0.0.4000,0x5005076300C213e9,0x5022000000000000
+rd.zfcp=0.0.4000
--
**rd.zfcp.conf=0**::
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
+SquashFS with read-only filesystem image::: The system will boot with a read
+only filesystem from the SquashFS and apply a writable device-mapper snapshot
over the read only filesystem. Using this method ensures a relatively fast
boot and lower RAM usage. Users **must be careful** to avoid writing too many
-blocks to the snapshot volume. Once the blocks of the snapshot are exhaused,
-the live filesystem becomes unusable and requires a reboot.
+blocks to the snapshot volume. Once the blocks of the snapshot overlay are
+exhausted, the root filesystem becomes read only and may cause application
+failures. The overlay file is marked 'Overflow', and a difficult recovery is
+required to repair and enlarge the overlay offline. Non-persistent overlays
+are sparse files in RAM that only consume content space as required blocks are
+allocated. They default to an apparent size of 32 GiB in RAM. The size can be
+adjusted with the **rd.live.overlay.size=** kernel command line option.
+
The filesystem structure is expected to be:
+
[listing]
--
-squashfs.img | Squashfs downloaded via network
+squashfs.img | Squashfs from LiveCD .iso downloaded via network
!(mount)
/LiveOS
- |- ext3fs.img | Filesystem image to mount read-only
+ |- rootfs.img | Filesystem image to mount read-only
!(mount)
/bin | Live filesystem
/boot |
options are required other than **root=live:<URL>** to specify the location
of your squashed filesystem.
+
-writable filesystem image::: The system will retrieve a compressed filesystem
-image, connect it to a loopback device, and mount it as a writable volume. 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.
+- The compressed SquashFS image can be copied during boot to RAM at
+`/run/initramfs/squashed.img` by using the **rd.live.ram=1** option.
+- A device with a persistent overlay can be booted read only by using the
+**rd.live.overlay.readonly** option on the kernel command line. This will
+cause a temporary, writable overlay to be stacked over a read-only snapshot
+of the root filesystem.
++
+Uncompressed live filesystem image:::
+When the live system was installed with the '--skipcompress' option of the
+__livecd-iso-to-disk__ installation script for Live USB devices, the root
+filesystem image, `rootfs.img`, is expanded on installation and no SquashFS
+is involved during boot.
++
+- If **rd.live.ram=1** is used in this situation, the full, uncompressed
+root filesystem is copied during boot to `/run/initramfs/rootfs.img` in the
+`/run` tmpfs.
++
+- If **rd.live.overlay=none** is provided as a kernel command line option,
+a writable, linear device-mapper target is created on boot with no overlay.
+
+writable filesystem image:::
+The system will retrieve a compressed filesystem image, extract it to
+`/run/initramfs/fsimg/rootfs.img`, connect it to a loop device, create a
+writable, linear device-mapper target at `/dev/mapper/live-rw`, and mount that
+as a writable volume at `/`. More RAM is required during boot but the live
+filesystem is easier to manage if it becomes full. Users can make a filesystem
+image of any size and that size will be maintained when the system boots. There
+is no persistence of root filesystem changes between boots with this option.
+
The filesystem structure is expected to be:
+
--
rootfs.tgz | Compressed tarball containing fileystem image
!(unpack)
- /rootfs.img | Filesystem image
+ /rootfs.img | Filesystem image at /run/initramfs/fsimg/
!(mount)
/bin | Live filesystem
/boot |
... |
--
+
-To use this boot option, ensure that **rd.writable_fsimg=1** is in your kernel
+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.
+of your compressed filesystem image tarball or SquashFS image.
=====================
+**rd.writable.fsimg=**1::
+Enables writable filesystem support. The system will boot with a fully
+writable (but non-persistent) filesystem without snapshots __(see notes above
+about available live boot options)__. You can use the **rootflags** option to
+set mount options for the live filesystem as well __(see documentation about
+rootflags in the **Standard** section above)__.
+This implies that the whole image is copied to RAM before the boot continues.
++
+NOTE: There must be enough free RAM available to hold the complete image.
++
+This method is very suitable for diskless boots.
+
**root=**live:__<url>__::
Boots a live image retrieved from __<url>__. Valid handlers: __http, https, ftp, torrent, tftp__.
+
Enables debug output from the live boot process.
**rd.live.dir=**__<path>__::
-Specifies the directory within the squashfs where the ext3fs.img or rootfs.img
-can be found. By default, this is __LiveOS__.
+Specifies the directory within the boot device where the squashfs.img or
+rootfs.img can be found. By default, this is __LiveOS__.
+
+**rd.live.squashimg=**__<filename of SquashFS image>__::
+Specifies the filename for a SquashFS image of the root filesystem.
+By default, this is __squashfs.img__.
**rd.live.ram=**1::
Copy the complete image to RAM and use this for booting. This is useful
-when the image resides on i.e. a DVD which needs to be ejected later on.
+when the image resides on, i.e., a DVD which needs to be ejected later on.
-**rd.live.overlay=**_<devspec>_:_(<pathspec>|auto)__
+**rd.live.overlay=**__<devspec>__:__(<pathspec>|auto)__|__none__::
Allow the usage of a permanent overlay.
-_<devspec>_ specifies the path to a device with a mountable filesystem.
-_<pathspec>_ is the path to a file within that filesystem, which shall be used to
-persist the changes made to the device specified by **root=live:__<url>__** option.
+- _<devspec>_ specifies the path to a device with a mountable filesystem.
+- _<pathspec>_ is the path to a file within that filesystem, which shall be
+used to persist the changes made to the device specified by the
+**root=live:__<url>__** option.
+- _none_ specifies no overlay when an uncompressed live root filesystem is
+available.
+If a persistent overlay is detected at the standard LiveOS path, the overlay &
+overlay type detected (whether Device-mapper or OverlayFS) will be used.
+
[listing]
.Example
rd.live.overlay=/dev/sdb1:persistent-overlay.img
--
+**rd.live.overlay.size=**__<size_MiB>__::
+Specifies a non-persistent overlay size in MiB. The default is _32768_.
+
+**rd.live.overlay.readonly=**1::
+Specifies a non-persistent, writable snapshot overlay to be stacked over a
+read-only snapshot of the root filesystem, `/dev/mapper/live-ro`, or a read-
+only loop device of a writable `rootfs.img`.
+
+**rd.live.overlay.reset=**1::
+Specifies that a persistent overlay should be reset on boot. All root
+filesystem changes are vacated by this action.
+
**rd.live.overlay.thin=**1::
Enables the usage of thin snapshots instead of classic dm snapshots.
-The advantage of thin snapshots is, that they support discards, and will free
-blocks which 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
+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.writable.fsimg=**1::
-Enables writable filesystem support. The system will boot with a fully
-writable 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.
+**rd.live.overlay.overlayfs=**1::
+Enables the use of the **OverlayFS** kernel module, if available, to provide a
+copy-on-write union directory for the root filesystem. OverlayFS overlays are
+directories of the files that have changed on the read-only base (lower)
+filesystem. The root filesystem is provided through a special overlay type
+mount that merges the lower and upper directories. If an OverlayFS upper
+directory is not present on the boot device, a tmpfs directory will be created
+at /run/overlayfs to provide temporary storage. Persistent storage can be
+provided on vfat or msdos formatted devices by supplying the OverlayFS upper
+directory within an embedded filesystem that supports the creation of trusted.*
+extended attributes and provides a valid d_type in readdir responses, such as
+with ext4 and xfs. On non-vfat-formatted devices, a persistent OverlayFS
+overlay can extend the available root filesystem storage up to the capacity of
+the LiveOS device.
+
+If a persistent overlay is detected at the standard LiveOS path, the overlay &
+overlay type detected (whether OverlayFS or Device-mapper) will be used.
+
+The **rd.live.overlay.readonly** option, which allows a persistent overlayfs to
+be mounted read only through a higher level transient overlay directory, has
+been implemented through the multiple lower layers feature of OverlayFS.
Plymouth Boot Splash