Ubuntu Manpage: live-boot - System Boot Components

Provided by: open-infrastructure-system-boot_20190301-lts1-2_all

NAME

       live-boot - System Boot Components

DESCRIPTION

       live-boot  contains  the  components  that configure a live system during the boot process
       (early userspace).

       live-boot is a hook for the initramfs-tools, used to generate a initramfs capable to  boot
       live  systems,  such  as  those  created by live-helper(7). This includes the Live systems
       ISOs, netboot tarballs, and usb stick images.

       At boot time it will look for a (read-only) medium containing a "/live" directory where  a
       root  filesystems (often a compressed filesystem image like squashfs) is stored. If found,
       it will create a writable environment, using aufs, to boot the system from.

CONFIGURATION

       live-boot can be configured through a boot parameter or a configuration file.

       To configure  the  live-boot  parameters  used  by  default  in  a  live  image,  see  the
       --bootappend-live option in the lb_config(1) manual page.

   Kernel Parameters
       live-boot is only activated if 'boot=live' was used as a kernel parameter.

       In addition, there are some more boot parameters to influence the behaviour, see below.

   Configuration Files
       live-boot  can  be configured (but not activated) through configuration files. Those files
       can   be   placed   either   in   the   root   filesystem   itself   (/etc/live/boot.conf,
       /etc/live/boot/*),  or on the live media (live/boot.conf, live/boot/*).  These environment
       variables can only be set in the configuration files:

       DISABLE_CDROM=[true|false]
              Disable support for booting from CD-ROMs.  If set to 'y' mkinitramfs will build  an
              initramfs without the kernel modules for reading CD-ROMs.

       DISABLE_FAT=[true|false]
              Disable  support for booting from FAT file systems.  If set to 'y' mkinitramfs will
              build an initramfs without the kernel module vfat and some nls_* modules.

       DISABLE_FUSE=[true|false]
              Disable  support  for  booting  from  FUSE-based  file  systems.   If  set  to  'y'
              mkinitramfs will build an initramfs without the kernel module fuse and file systems
              that depend on it (like curlftpfs and httpfs2).

       DISABLE_NTFS=[true|false]
              Disable support for booting from NTFS file systems.  If set to 'y' mkinitramfs will
              build an initramfs without the kernel module ntfs.

       DISABLE_USB=[true|false]
              Disable support for booting from USB devices.  If set to 'y' mkinitramfs will build
              an initramfs without the kernel module sd_mod.

       MINIMAL=[true|false]
              Build a minimal initramfs.  If set to  'y'  mkinitramfs  will  build  an  initramfs
              without some udev scripts and without rsync.

       PERSISTENCE_FSCK=[true|false]
              Run  fsck  on  persistence  filesystem  on boot. Will attempt to repair errors. The
              execution log will be saved in /var/log/live/fsck.log.

       FSCKFIX=[true|false]
              If PERSISTENCE_FSCK or forcefsck are set, will pass -y to  fsck  to  stop  it  from
              asking questions interactively and assume yes to all queries.

OPTIONS

live-boot currently features the following parameters.

access=ACCESS
Set the accessibility level for physically or visually impaired users. ACCESS must be
one of v1, v2, v3, m1, or m2. v1=lesser visual impairment, v2=moderate visual
impairment, v3=blindness, m1=minor motor difficulties, m2=moderate motor difficulties.

console=TTY,SPEED
Set the default console to be used with the "live-getty" option. Example:
"console=ttyS0,115200"

debug
Makes initramfs boot process more verbose.
Use: debug=1
Without setting debug to a value the messages may not be shown.

fetch=URL

httpfs=URL
Another form of netboot by downloading a squashfs image from a given URL. The fetch
method copies the image to RAM and the httpfs method uses FUSE and httpfs2 to mount
the image in place. Copying to RAM requires more memory and might take a long time for
large images. However, it is more likely to work correctly because it does not require
networking afterwards and the system operates faster once booted because it does not
require to contact the server anymore.
Due to current limitations in busybox's wget and DNS resolution, an URL can not
contain a hostname but an IP address only.
Not working: http://example.com/path/to/your_filesystem.squashfs
Working: http://1.2.3.4/path/to/your_filesystem.squashfs
Also note that therefore it's currently not possible to fetch an image from a name-
based virtualhost of an httpd if it is sharing the IP address with the main httpd
instance.
You may also use the live ISO image in place of the squashfs image.

iscsi=server-ip[,server-port];target-name
Boot from an iSCSI target that has an ISO or disk live image as one of its LUNs. The
specified target is searched for a LUN which looks like a live medium. If you use the
iscsitarget software iSCSI target solution your ietd.conf might look like this:
# The target-name you specify in the iscsi= parameter
Target <target-name>
Lun 0 Path=<path-to-your-live-image.iso>,Type=fileio,IOMode=ro
# If you want to boot multiple machines you might want to look at tuning some
parameters like
# Wthreads or MaxConnections

findiso=/PATH/TO/IMAGE
Look for the specified ISO file on all disks where it usually looks for the .squashfs
file (so you don't have to know the device name as in fromiso=....).

forcefsck
Run fsck on persistence filesystem on boot. Will attempt to repair errors. The
execution log will be saved in /var/log/live/fsck.log.

fromiso=/PATH/TO/IMAGE
Use a filesystem from within an ISO image that's available on live-media. The first
part of the argument should be the block device where the image is stored, followed by
the path and filename (e.g. fromiso=/dev/sda1/live/image.iso).
Alternatively, it can be used to boot from an ISO embedded into an initrd (e.g.
fromiso=/live/image.iso).

ignore_uuid
Do not check that any UUID embedded in the initramfs matches the discovered medium.
live-boot may be told to generate a UUID by setting LIVE_GENERATE_UUID=1 when building
the initramfs.

verify-checksums
If specified, an MD5 sum is calculated on the live media during boot and compared to
the value found in md5sum.txt found in the root directory of the live media.

ip=[DEVICE]:[CLIENT_IP]:[NETMASK]:[GATEWAY_IP]:[NAMESERVER]
[,[DEVICE]:[CLIENT_IP]:[NETMASK]:[GATEWAY_IP]:[NAMESERVER]]
Let you specify the name(s) and the options of the interface(s) that should be
configured at boot time. Do not specify this if you want to use dhcp (default). It
will be changed in a future release to mimic official kernel boot param specification
(e.g. ip=10.0.0.1::10.0.0.254:255.255.255.0::eth0,:::::eth1:dhcp).

ip=[frommedia]
If this variable is set, dhcp and static configuration are just skipped and the system
will use the (must be) media-preconfigured /etc/network/interfaces instead.

live-media-uuid=UUID
Override UUID embedded in the initramfs.

live-media-mount-opts=OPTS
This specific which mount opts to use for mounting live-media. Default: ro,noatime

{live-media|bootfrom}=DEVICE
If you specify one of this two equivalent forms, live-boot will first try to find this
device for the "/live" directory where the read-only root filesystem should reside. If
it did not find something usable, the normal scan for block devices is performed.
Instead of specifying an actual device name, the keyword 'removable' can be used to
limit the search of acceptable live media to removable type only. Note that if you
want to further restrict the media to usb mass storage only, you can use the
'removable-usb' keyword.

{live-media-encryption|encryption}=TYPE
live-boot will mount the encrypted rootfs TYPE, asking the passphrase, useful to build
paranoid live systems :-). TYPE supported so far is "aes" for loop-aes encryption
type.

live-media-offset=BYTES
This way you could tell live-boot that your image starts at offset BYTES in the above
specified or autodiscovered device, this could be useful to hide the live system ISO
or image inside another ISO or image, to create "clean" images.

live-media-path=PATH
Sets the path to the live filesystem on the medium. By default, it is set to '/live'
and you should not change that unless you have customized your media accordingly.

live-media-timeout=SECONDS
Set the timeout in seconds for the device specified by "live-media=" to become ready
before giving up.

module=NAME
Instead of using the default optional file "filesystem.module" (see below) another
file could be specified without the extension ".module"; it should be placed on
"/live" directory of the live medium.

netboot[=nfs|cifs]
This tells live-boot to perform a network mount. The parameter "nfsroot=" (with
optional "nfsopts="), should specify where is the location of the root filesystem.
With no args, will try cifs first, and if it fails nfs.

nfsopts=
This lets you specify custom nfs options.

nofastboot
This parameter disables the default disabling of filesystem checks in /etc/fstab. If
you have static filesystems on your harddisk and you want them to be checked at boot
time, use this parameter, otherwise they are skipped.

nopersistence
disables the "persistence" feature, useful if the bootloader (like syslinux) has been
installed with persistence enabled.

noeject
Do not prompt to eject the live medium.

ramdisk-size
This parameter defines a custom ramdisk size (it's the '-o size' option of tmpfs
mount). By default, there is no ramdisk size set, so the default of mount applies
(currently 50% of available RAM). Note that this option has currently no effect when
booting with toram.

overlay-size=SIZE
The size of the tmpfs mount (used for the upperdir union root mount) in bytes, and
rounded up to entire pages. This option accepts a suffix % to limit the instance to
that percentage of your physical RAM or a suffix k, m or g for Ki, Mi, Gi (binary kilo
(kibi), binary mega (mebi) and binary giga (gibi)). By default, 50% of available RAM
will be used.

swap=true
This parameter enables usage of local swap partitions.

persistence
live-boot will probe devices for persistence media. These can be partitions (with the
correct GPT name), filesystems (with the correct label) or image files (with the
correct file name). Overlays are labeled/named "persistence" (see
persistence.conf(5)). Overlay image files are named "persistence".

persistence-encryption=TYPE1,TYPE2 ... TYPEn
This option determines which types of encryption that are allowed to be used when
probing devices for persistence media. If "none" is in the list, we allow unencrypted
media; if "luks" is in the list, we allow LUKS-encrypted media. Whenever a device
containing encrypted media is probed the user will be prompted for the passphrase. The
default value is "none".

persistence-media={removable|removable-usb}
If you specify the keyword 'removable', live-boot will try to find persistence
partitions on removable media only. Note that if you want to further restrict the
media to usb mass storage only, you can use the 'removable-usb' keyword.

persistence-method=TYPE1,TYPE2 ... TYPEn
This option determines which types of persistence media we allow. If "overlay" is in
the list, we consider overlays (i.e. "live-rw" and "home-rw"). The default is
"overlay".

persistence-path=PATH
live-boot will look for persistency files in the root directory of a partition, with
this parameter, the path can be configured so that you can have multiple directories
on the same partition to store persistency files.

persistence-read-only
Filesystem changes are not saved back to persistence media. In particular, overlays
and netboot NFS mounts are mounted read-only.

persistence-storage=TYPE1,TYPE2 ... TYPEn
This option determines which types of persistence storage to consider when probing for
persistence media. If "filesystem" is in the list, filesystems with matching labels
will be used; if "file" is in the list, all filesystems will be probed for archives
and image files with matching filenames. The default is "file,filesystem".

persistence-label=LABEL
live-boot will use the name "LABEL" instead of "persistence" when searching for
persistent storage. LABEL can be any valid filename, partition label, or GPT name.

noeject
This option causes live-boot to reboot without attempting to eject the media and
without asking the user to remove the boot media.

showmounts
This parameter will make live-boot to show on "/" the ro filesystems (mostly
compressed) on "/lib/live". This is not enabled by default because could lead to
problems by applications like "mono" which store binary paths on installation.

silent
If you boot with the normal quiet parameter, live-boot hides most messages of its own.
When adding silent, it hides all.

todisk=DEVICE
Adding this parameter, live-boot will try to copy the entire read-only media to the
specified device before mounting the root filesystem. It probably needs a lot of free
space. Subsequent boots should then skip this step and just specify the
"live-media=DEVICE" boot parameter with the same DEVICE used this time.

toram
Adding this parameter, live-boot will try to copy the whole read-only media to the
computer's RAM before mounting the root filesystem. This could need a lot of ram,
according to the space used by the read-only media.

union=overlay|aufs
By default, live-boot uses overlay. With this parameter, you can switch to aufs.

FILES (old)

       /etc/live.conf
           Some variables can be configured via this config file (inside the live system).

       live/filesystem.module
           This optional file  (inside  the  live  media)  contains  a  list  of  white-space  or
           carriage-return-separated  file  names  corresponding  to  disk  images in the "/live"
           directory. If this file exists, only images listed here will be merged into  the  root
           aufs,  and  they will be loaded in the order listed here. The first entry in this file
           will be the "lowest" point in the aufs, and the last file in this list will be on  the
           "top"  of  the  aufs,  directly  below /overlay.  Without this file, any images in the
           "/live" directory are loaded in alphanumeric order.

FILES

       /etc/live/boot.conf

       /etc/live/boot/*

       live/boot.conf

       live/boot/*

       persistence.conf

HOMEPAGE

       More information about live-boot and the Live Systems project can be found on the homepage
       at <http://live-systems.org/> and in the manual at <http://live-systems.org/manual/>.

BUGS

       Bugs  can  be  reported  by  submitting  a  bugreport for the live-boot package in the Bug
       Tracking System at <http://bugs.debian.org/> or by writing a  mail  to  the  Live  Systems
       mailing list at <debian-live@lists.debian.org>.

AUTHOR

       live-boot was written by Daniel Baumann <mail@daniel-baumann.ch>.