Appendix C. Boot options reference
This section contains information about some of the boot options that you can use to modify the default behavior of the installation program. For Kickstart and advanced boot options, see the Boot options for RHEL installer document.
C.1. Installation source boot options
This section describes various installation source boot options.
inst.repo=boot option specifies the installation source, that is, the location providing the package repositories and a valid
.treeinfofile that describes them. For example:
inst.repo=cdrom. The target of the
inst.repo=option must be one of the following installation media:
an installable tree, which is a directory structure containing the installation program images, packages, and repository data as well as a valid
- a DVD (a physical disk present in the system DVD drive)
an ISO image of the full Red Hat Enterprise Linux installation DVD, placed on a disk or a network location accessible to the system.
inst.repo=boot option to configure different installation methods using different formats. The following table contains details of the
inst.repo=boot option syntax:
Table C.1. Types and format for the inst.repo= boot option and installation source
Source type Boot option format Source format
Installation DVD as a physical disk. [a]
Mountable device (HDD and USB stick)
Image file of the installation DVD.
Image file of the installation DVD, or an installation tree, which is a complete copy of the directories and files on the installation DVD. [b]
Installation tree that is a complete copy of the directories and files on the installation DVD.
inst.repo=hmc[a] If device is left out, installation program automatically searches for a drive containing the installation DVD.[b] The NFS Server option uses NFS protocol version 3 by default. To use a different version, add
nfsvers=Xto options, replacing X with the version number that you want to use.
- an installable tree, which is a directory structure containing the installation program images, packages, and repository data as well as a valid
Set disk device names with the following formats:
Kernel device name, for example
File system label, for example
File system UUID, for example
Non-alphanumeric characters must be represented as
\xNN, where NN is the hexadecimal representation of the character. For example,
\x20 is a white space
inst.addrepo=boot option to add an additional repository that you can use as another installation source along with the main repository (
inst.repo=). You can use the
inst.addrepo=boot option multiple times during one boot. The following table contains details of the
inst.addrepo=boot option syntax.Note
REPO_NAMEis the name of the repository and is required in the installation process. These repositories are only used during the installation process; they are not installed on the installed system.
For more information about unified ISO, see Unified ISO.
Table C.2. Installation sources and boot option format
|Boot option format
Installable tree at a URL
Looks for the installable tree at a given URL.
Installable tree at an NFS path
Looks for the installable tree at a given NFS path. A colon is required after the host. The installation program passes everything after
Installable tree in the installation environment
Looks for the installable tree at the given location in the installation environment. To use this option, the repository must be mounted before the installation program attempts to load the available software groups. The benefit of this option is that you can have multiple repositories on one bootable ISO, and you can install both the main repository and additional repositories from the ISO. The path to the additional repositories is
Mounts the given <device> partition and installs from the ISO that is specified by the <path>. If the <path> is not specified, the installation program looks for a valid installation ISO on the <device>. This installation method requires an ISO with a valid installable tree.
inst.stage2=boot option specifies the location of the installation program’s runtime image. This option expects the path to a directory that contains a valid
.treeinfofile and reads the runtime image location from the
.treeinfofile. If the
.treeinfofile is not available, the installation program attempts to load the image from
When you do not specify the
inst.stage2option, the installation program attempts to use the location specified with the
Use this option when you want to manually specify the installation source in the installation program at a later time. For example, when you want to select the Content Delivery Network (CDN) as an installation source. The installation DVD and Boot ISO already contain a suitable
inst.stage2option to boot the installation program from the respective ISO.
If you want to specify an installation source, use the
By default, the
inst.stage2=boot option is used on the installation media and is set to a specific label; for example,
inst.stage2=hd:LABEL=RHEL-x-0-0-BaseOS-x86_64. If you modify the default label of the file system that contains the runtime image, or if you use a customized procedure to boot the installation system, verify that the
inst.stage2=boot option is set to the correct value.
inst.noverifysslboot option to prevent the installer from verifying SSL certificates for all HTTPS connections with the exception of additional Kickstart repositories, where
--noverifysslcan be set per repository.
For example, if your remote installation source is using self-signed SSL certificates, the
inst.noverifysslboot option enables the installer to complete the installation without verifying the SSL certificates.
Example when specifying the source using
Example when specifying the source using
inst.stage2.allboot option to specify several HTTP, HTTPS, or FTP sources. You can use the
inst.stage2=boot option multiple times with the
inst.stage2.alloption to fetch the image from the sources sequentially until one succeeds. For example:
inst.stage2.all inst.stage2=http://hostname1/path_to_install_tree/ inst.stage2=http://hostname2/path_to_install_tree/ inst.stage2=http://hostname3/path_to_install_tree/
inst.dd=boot option is used to perform a driver update during the installation. For more information about how to update drivers during installation, see the Performing an advanced RHEL 8 installation document.
This option eliminates the requirement of an external network setup and expands the installation options. When booting from a Binary DVD, the installation program prompts you to enter additional kernel parameters. To set the DVD as an installation source, append the
inst.repo=hmcoption to the kernel parameters. The installation program then enables support element (SE) and hardware management console (HMC) file access, fetches the images for stage2 from the DVD, and provides access to the packages on the DVD for software selection.
inst.proxy=boot option is used when performing an installation from a HTTP, HTTPS, and FTP protocol. For example:
inst.nosave=boot option to control the installation logs and related files that are not saved to the installed system, for example
all. You can combine multiple values separated by a comma. For example,
inst.nosaveboot option is used for excluding files from the installed system that cannot be removed by a Kickstart %post script, such as logs and input/output Kickstart results.
- Disables the ability to save the input Kickstart results.
- Disables the ability to save the output Kickstart results generated by the installation program.
- Disables the ability to save the input and output Kickstart results.
- Disables the ability to save all installation logs.
- Disables the ability to save all Kickstart results, and all logs.
inst.multilibboot option to set DNF’s
multilib_policyto all, instead of best.
inst.memcheckboot option performs a check to verify that the system has enough RAM to complete the installation. If there is not enough RAM, the installation process is stopped. The system check is approximate and memory usage during installation depends on the package selection, user interface, for example graphical or text, and other parameters.
inst.nomemcheckboot option does not perform a check to verify if the system has enough RAM to complete the installation. Any attempt to perform the installation with less than the recommended minimum amount of memory is unsupported, and might result in the installation process failing.
C.2. Network boot options
If your scenario requires booting from an image over the network instead of booting from a local image, you can use the following options to customize network booting.
Initialize the network with the
dracut tool. For complete list of
dracut options, see the
dracut.cmdline(7) man page.
ip=boot option to configure one or more network interfaces. To configure multiple interfaces, use one of the following methods;
ipoption multiple times, once for each interface; to do so, use the
rd.neednet=1option, and specify a primary boot interface using the
ipoption once, and then use Kickstart to set up further interfaces. This option accepts several different formats. The following tables contain information about the most common options.
- use the
In the following tables:
ipparameter specifies the client IP address and
IPv6requires square brackets, for example 192.0.2.1 or [2001:db8::99].
gatewayparameter is the default gateway.
IPv6requires square brackets.
netmaskparameter is the netmask to be used. This can be either a full netmask (for example, 255.255.255.0) or a prefix (for example, 64).
hostnameparameter is the host name of the client system. This parameter is optional.
Table C.3. Boot option formats to configure the network interface
Boot option format Configuration method
Automatic configuration of any interface
Automatic configuration of a specific interface
Static configuration, for example, IPv4:
Automatic configuration of a specific interface with an override
Configuration methods for the automatic interface
automatic configuration of a specific interface with an overrideopens the interface using the specified method of automatic configuration, such as
dhcp, but overrides the automatically obtained IP address, gateway, netmask, host name or other specified parameters. All parameters are optional, so specify only the parameters that you want to override.
methodparameter can be any of the following:
- IPv6 DHCP
- IPv6 automatic configuration
- iSCSI Boot Firmware Table (iBFT)
If you use a boot option that requires network access, such as
inst.ks=http://host/path, without specifying the
ipoption, the default value of the
To connect to an iSCSI target automatically, activate a network device for accessing the target by using the
nameserver=option specifies the address of the name server. You can use this option multiple times.Note
ip=parameter requires square brackets. However, an IPv6 address does not work with square brackets. An example of the correct syntax to use for an IPv6 address is
bootdev=option specifies the boot interface. This option is mandatory if you use more than one
ifname=options assigns an interface name to a network device with a given MAC address. You can use this option multiple times. The syntax is
ifname=interface:MAC. For example:
ifname=option is the only supported way to set custom network interface names during installation.
inst.dhcpclass=option specifies the DHCP vendor class identifier. The
dhcpdservice sees this value as
vendor-class-identifier. The default value is
inst.waitfornet=SECONDSboot option causes the installation system to wait for network connectivity before installation. The value given in the
SECONDSargument specifies the maximum amount of time to wait for network connectivity before timing out and continuing the installation process even if network connectivity is not present.
vlan=option to configure a Virtual LAN (VLAN) device on a specified interface with a given name. The syntax is
vlan=name:interface. For example:
This configures a VLAN device named
enp0s1interface. The name can take the following forms:
bond=option to configure a bonding device with the following syntax:
bond=name[:interfaces][:options]. Replace name with the bonding device name, interfaces with a comma-separated list of physical (Ethernet) interfaces, and options with a comma-separated list of bonding options. For example:
For a list of available options, execute the
team=option to configure a team device with the following syntax:
team=name:interfaces. Replace name with the desired name of the team device and interfaces with a comma-separated list of physical (Ethernet) devices to be used as underlying interfaces in the team device. For example:
bridge=option to configure a bridge device with the following syntax:
bridge=name:interfaces. Replace name with the desired name of the bridge device and interfaces with a comma-separated list of physical (Ethernet) devices to be used as underlying interfaces in the bridge device. For example:
C.3. Console boot options
This section describes how to configure boot options for your console, monitor display, and keyboard.
console=option to specify a device that you want to use as the primary console. For example, to use a console on the first serial port, use
console=ttyS0. When using the
console=argument, the installation starts with a text UI. If you must use the
console=option multiple times, the boot message is displayed on all specified console. However, the installation program uses only the last specified console. For example, if you specify
console=ttyS0 console=ttyS1, the installation program uses
inst.lang=option to set the language that you want to use during the installation. To view the list of locales, enter the command
locale -a | grep _or the
localectl list-locales | grep _command.
inst.singlelangoption to install in single language mode, which results in no available interactive options for the installation language and language support configuration. If a language is specified using the
inst.langboot option or the
langKickstart command, then it is used. If no language is specified, the installation program defaults to
inst.geoloc=option to configure geolocation usage in the installation program. Geolocation is used to preset the language and time zone, and uses the following syntax:
valuecan be any of the following parameters:
Use the Fedora GeoIP API:
Use the Hostip.info GeoIP API:
If you do not specify the
inst.geoloc=option, the default option is
- Disable geolocation:
inst.keymap=option to specify the keyboard layout to use for the installation.
inst.cmdlineoption to force the installation program to run in command-line mode. This mode does not allow any interaction, and you must specify all options in a Kickstart file or on the command line.
inst.graphicaloption to force the installation program to run in graphical mode. The graphical mode is the default.
inst.textoption to force the installation program to run in text mode instead of graphical mode.
inst.noninteractiveboot option to run the installation program in a non-interactive mode. User interaction is not permitted in the non-interactive mode, and
inst.noninteractiveyou can use the
inst.nointeractiveoption with a graphical or text installation. When you use the
inst.noninteractiveoption in text mode, it behaves the same as the
inst.resolution=option to specify the screen resolution in graphical mode. The format is
NxM, where N is the screen width and M is the screen height (in pixels). The recommended resolution is 1024x768.
inst.vncoption to run the graphical installation using Virtual Network Computing (VNC). You must use a VNC client application to interact with the installation program. When VNC sharing is enabled, multiple clients can connect. A system installed using VNC starts in text mode.
inst.vncpassword=option to set a password on the VNC server that is used by the installation program.
inst.vncconnect=option to connect to a listening VNC client at the given host location, for example,
inst.vncconnect=<host>[:<port>]The default port is 5900. You can use this option by entering the command
inst.xdriver=option to specify the name of the X driver to use both during installation and on the installed system.
inst.usefbxoption to prompt the installation program to use the frame buffer X driver instead of a hardware-specific driver. This option is equivalent to the
modprobe.blacklist=option to blocklist or completely disable one or more drivers. Drivers (mods) that you disable using this option cannot load when the installation starts. After the installation finishes, the installed system retains these settings. You can find a list of the blocklisted drivers in the
/etc/modprobe.d/directory. Use a comma-separated list to disable multiple drivers. For example:
inst.xtimeout=option to specify the timeout in seconds for starting X server.
inst.sshdoption to start the
sshdservice during installation, so that you can connect to the system during the installation using SSH, and monitor the installation progress. For more information about SSH, see the
ssh(1)man page. By default, the
sshdoption is automatically started only on the 64-bit IBM Z architecture. On other architectures,
sshdis not started unless you use the
During installation, the root account has no password by default. You can set a root password during installation with the
inst.kdump_addon=option to enable or disable the Kdump configuration screen (add-on) in the installation program. This screen is enabled by default; use
inst.kdump_addon=offto disable it. Disabling the add-on disables the Kdump screens in both the graphical and text-based interface as well as the
%addon com_redhat_kdumpKickstart command.
C.4. Debug boot options
This section describes the options you can use when debugging issues.
inst.rescueoption to run the rescue environment for diagnosing and fixing systems. For example, you can repair a filesystem in rescue mode.
inst.updates=option to specify the location of the
updates.imgfile that you want to apply during installation. The
updates.imgfile can be derived from one of several sources.
Source Description Example
Updates from a network
Specify the network location of
updates.img. This does not require any modification to the installation tree. To use this method, edit the kernel command line to include
Updates from a disk image
updates.imgon a floppy drive or a USB key. This can be done only with an
ext2filesystem type of
updates.img. To save the contents of the image on your floppy drive, insert the floppy disc and run the command.
dd if=updates.img of=/dev/fd0 bs=72k count=20. To use a USB key or flash media, replace
/dev/fd0with the device name of your USB flash drive.
Updates from an installation tree
If you are using a CD, disk, HTTP, or FTP install, save the
updates.imgin the installation tree so that all installations can detect the
.imgfile. The file name must be
For NFS installs, save the file in the
images/directory, or in the
inst.loglevel=option to specify the minimum level of messages logged on a terminal. This option applies only to terminal logging; log files always contain messages of all levels. Possible values for this option from the lowest to highest level are:
The default value is
info, which means that by default, the logging terminal displays messages ranging from
Sends log messages to the
syslogprocess on the specified host when the installation starts. You can use
inst.syslog=only if the remote
syslogprocess is configured to accept incoming connections.
inst.virtiolog=option to specify which virtio port (a character device at
/dev/virtio-ports/name) to use for forwarding logs. The default value is
Controls the usage of zRAM swap during installation. The option creates a compressed block device inside the system RAM and uses it for swap space instead of using the disk. This setup allows the installation program to run with less available memory and improve installation speed. You can configure the
inst.zram=option using the following values:
- inst.zram=1 to enable zRAM swap, regardless of system memory size. By default, swap on zRAM is enabled on systems with 2 GiB or less RAM.
- inst.zram=0 to disable zRAM swap, regardless of system memory size. By default, swap on zRAM is disabled on systems with more than 2 GiB of memory.
stage 2image in
images/install.imginto RAM. Note that this increases the memory required for installation by the size of the image which is usually between 400 and 800MB.
- Prevent the installation program from rebooting when a fatal error occurs, or at the end of the installation process. Use it capture installation logs which would be lost upon reboot.
- Prevent a shell on terminal session 2 (tty2) during installation.
- Prevent the use of tmux during installation. The output is generated without terminal control characters and is meant for non-interactive uses.
Sends all the logs to a remote
host:portusing a TCP connection. The connection is retired if there is no listener and the installation proceeds as normal.
C.5. Storage boot options
This section describes the options you can specify to customize booting from a storage device.
Use this option with caution. If you have a disk that is incorrectly identified as part of a firmware RAID array, it might have some stale RAID metadata on it that must be removed using the appropriate tool such as,
- Disables support for multipath devices. Use this option only if your system has a false-positive that incorrectly identifies a normal block device as a multipath device.
Use this option with caution. Do not use this option with multipath hardware. Using this option to install to a single path of a multipath device is not supported.
Forces the installation program to install partition information to a GUID Partition Table (GPT) instead of a Master Boot Record (MBR). This option is not valid on UEFI-based systems, unless they are in BIOS compatibility mode. Normally, BIOS-based systems and UEFI-based systems in BIOS compatibility mode attempt to use the MBR schema for storing partitioning information, unless the disk is 2^32 sectors in size or larger. Disk sectors are typically 512 bytes in size, meaning that this is usually equivalent to 2 TiB. The
inst.gptboot option allows a GPT to be written to smaller disks.
inst.wait_for_disks=option to specify the number of seconds installation program to wait for disk devices to appear at the beginning of the installation. Use this option when you use the
OEMDRV-labeleddevice to automatically load the Kickstart file or the kernel drivers but the device takes longer time to appear during the boot process. By default, installation program waits for
0seconds to minimize the delay.
C.6. Deprecated boot options
This section contains information about deprecated boot options. These options are still accepted by the installation program but they are deprecated and are scheduled to be removed in a future release of Red Hat Enterprise Linux.
methodoption is an alias for
dns. Note that nameserver does not accept comma-separated lists; use multiple nameserver options instead.
- netmask, gateway, hostname
hostnameoptions are provided as part of the
BOOTIFoption is used automatically, so there is no requirement to use
Table C.5. Values for the ksdevice boot option
Ignored as this option is the same as the default behavior
Ignored as this option is the default if
C.7. Removed boot options
This section contains the boot options that have been removed from Red Hat Enterprise Linux.
dracut provides advanced boot options. For more information about
dracut, see the
dracut.cmdline(7) man page.
- askmethod, asknetwork
initramfsis completely non-interactive, so the
asknetworkoptions have been removed. Use
inst.repoor specify the appropriate network options.
- blacklist, nofirewire
modprobeoption now handles blocklisting kernel modules. Use
modprobe.blacklist=<mod1>,<mod2>. You can blocklist the firewire module by using
headless=option specified that the system that is being installed to does not have any display hardware, and that the installation program is not required to look for any display hardware.
inst.decoratedoption was used to specify the graphical installation in a decorated window. By default, the window is not decorated, so it does not have a title bar, resize controls, and so on. This option was no longer required.
- essid, wepkey, wpakey
- Dracut does not support wireless networking.
- This option was no longer required.
This option was removed because many options are available for debugging dracut-based
dracut option rd.live.checkoption.
For a remote display of the UI, use the
- This option was no longer required because the default TERM setting behaves as expected.
ipv6 is built into the kernel and cannot be removed by the installation program. You can disable ipv6 by using
ipv6.disable=1. This setting is used by the installed system.
- This option was no longer required because the installation program no longer handles upgrades.