Appendix C. Boot options reference

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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.


The inst.repo= boot option specifies the installation source, that is, the location providing the package repositories and a valid .treeinfo file 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 .treeinfo file
  • 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.

    Use the 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 typeBoot option formatSource format

    CD/DVD drive


    Installation DVD as a physical disk. [a]

    Mountable device (HDD and USB stick)


    Image file of the installation DVD.

    NFS Server


    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]

    HTTP Server


    Installation tree that is a complete copy of the directories and files on the installation DVD.

    HTTPS Server


    FTP Server




    [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=X to options, replacing X with the version number that you want to use.

Set disk device names with the following formats:

  • Kernel device name, for example /dev/sda1 or sdb2
  • File system label, for example LABEL=Flash or LABEL=RHEL8
  • File system UUID, for example UUID=8176c7bf-04ff-403a-a832-9557f94e61db

Non-alphanumeric characters must be represented as \xNN, where NN is the hexadecimal representation of the character. For example, \x20 is a white space (" ").


Use the 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.


The REPO_NAME is 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
Installation sourceBoot option formatAdditional information

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 nfs:// directly to the mount command instead of parsing URLs according to RFC 2224.

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 /run/install/source/REPO_ISO_PATH. Additionally, you can mount the repository directory in the %pre section in the Kickstart file. The path must be absolute and start with /, for example inst.addrepo=REPO_NAME,file:///<path>



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.


The 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 .treeinfo file and reads the runtime image location from the .treeinfo file. If the .treeinfo file is not available, the installation program attempts to load the image from images/install.img.

When you do not specify the inst.stage2 option, the installation program attempts to use the location specified with the inst.repo option.

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.stage2 option to boot the installation program from the respective ISO.

If you want to specify an installation source, use the inst.repo= option instead.


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.


Use the inst.noverifyssl boot option to prevent the installer from verifying SSL certificates for all HTTPS connections with the exception of additional Kickstart repositories, where --noverifyssl can be set per repository.

For example, if your remote installation source is using self-signed SSL certificates, the inst.noverifyssl boot option enables the installer to complete the installation without verifying the SSL certificates.

Example when specifying the source using inst.stage2=

inst.stage2=https://hostname/path_to_install_image/ inst.noverifyssl

Example when specifying the source using inst.repo=

inst.repo=https://hostname/path_to_install_repository/ inst.noverifyssl


Use the inst.stage2.all boot option to specify several HTTP, HTTPS, or FTP sources. You can use the inst.stage2= boot option multiple times with the inst.stage2.all option to fetch the image from the sources sequentially until one succeeds. For example:

The 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=hmc option 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.

The inst.proxy= boot option is used when performing an installation from a HTTP, HTTPS, and FTP protocol. For example:


Use the inst.nosave= boot option to control the installation logs and related files that are not saved to the installed system, for example input_ks, output_ks, all_ks, logs and all. You can combine multiple values separated by a comma. For example,


The inst.nosave boot 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.
Use the inst.multilib boot option to set DNF’s multilib_policy to all, instead of best.
The inst.memcheck boot 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.
The inst.nomemcheck boot 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.


Use the ip= boot option to configure one or more network interfaces. To configure multiple interfaces, use one of the following methods;

  • use the ip option multiple times, once for each interface; to do so, use the rd.neednet=1 option, and specify a primary boot interface using the bootdev option.
  • use the ip option 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.

In the following tables:

  • The ip parameter specifies the client IP address and IPv6 requires square brackets, for example or [2001:db8::99].
  • The gateway parameter is the default gateway. IPv6 requires square brackets.
  • The netmask parameter is the netmask to be used. This can be either a full netmask (for example, or a prefix (for example, 64).
  • The hostname parameter 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 formatConfiguration method


    Automatic configuration of any interface


    Automatic configuration of a specific interface


    Static configuration, for example, IPv4:

    IPv6: ip=[2001:db8::1]::[2001:db8::fffe]


    Automatic configuration of a specific interface with an override

    Configuration methods for the automatic interface

    The method automatic configuration of a specific interface with an override opens 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.

    The method parameter 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 ip option, the default value of the ip option is ip=dhcp..
    • To connect to an iSCSI target automatically, activate a network device for accessing the target by using the ip=ibft boot option.

    The nameserver= option specifies the address of the name server. You can use this option multiple times.


    The 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 nameserver=2001:db8::1.

    The bootdev= option specifies the boot interface. This option is mandatory if you use more than one ip option.

    The 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:


    The ifname= option is the only supported way to set custom network interface names during installation.

    The inst.dhcpclass= option specifies the DHCP vendor class identifier. The dhcpd service sees this value as vendor-class-identifier. The default value is anaconda-$(uname -srm).
    Using the inst.waitfornet=SECONDS boot option causes the installation system to wait for network connectivity before installation. The value given in the SECONDS argument 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.

    Use the 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 vlan5 on the enp0s1 interface. The name can take the following forms:

  • VLAN_PLUS_VID: vlan0005
  • DEV_PLUS_VID: enp0s1.0005
  • DEV_PLUS_VID_NO_PAD: enp0s1.5


    Use the 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 modinfo bonding command.


    Use 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:


    Use the 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.

Use the 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 ttyS1.
Use the 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.
Use the inst.singlelang option 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.lang boot option or the lang Kickstart command, then it is used. If no language is specified, the installation program defaults to en_US.UTF-8.

Use the 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: inst.geoloc=value. The value can be any of the following parameters:

  • Disable geolocation: inst.geoloc=0
  • Use the Fedora GeoIP API: inst.geoloc=provider_fedora_geoip.
  • Use the GeoIP API: inst.geoloc=provider_hostip.

    If you do not specify the inst.geoloc= option, the default option is provider_fedora_geoip.

Use the inst.keymap= option to specify the keyboard layout to use for the installation.
Use the inst.cmdline option 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.
Use the inst.graphical option to force the installation program to run in graphical mode. The graphical mode is the default.
Use the inst.text option to force the installation program to run in text mode instead of graphical mode.
Use the inst.noninteractive boot option to run the installation program in a non-interactive mode. User interaction is not permitted in the non-interactive mode, and inst.noninteractive you can use the inst.nointeractive option with a graphical or text installation. When you use the inst.noninteractive option in text mode, it behaves the same as the inst.cmdline option.
Use 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.
Use the inst.vnc option 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.
Use the inst.vncpassword= option to set a password on the VNC server that is used by the installation program.
Use the 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 vncviewer -listen.
Use the inst.xdriver= option to specify the name of the X driver to use both during installation and on the installed system.
Use the inst.usefbx option to prompt the installation program to use the frame buffer X driver instead of a hardware-specific driver. This option is equivalent to the inst.xdriver=fbdev option.

Use 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:


You can use modprobe.blacklist in combination with the different command line options. For example, use it with the inst.dd option to ensure that an updated version of an existing driver is loaded from a driver update disc:

Use the inst.xtimeout= option to specify the timeout in seconds for starting X server.

Use the inst.sshd option to start the sshd service 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 sshd option is automatically started only on the 64-bit IBM Z architecture. On other architectures, sshd is not started unless you use the inst.sshd option.


During installation, the root account has no password by default. You can set a root password during installation with the sshpw Kickstart command.

Use 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=off to 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_kdump Kickstart command.

C.4. Debug boot options

This section describes the options you can use when debugging issues.

Use the inst.rescue option to run the rescue environment for diagnosing and fixing systems. For example, you can repair a filesystem in rescue mode.

Use the inst.updates= option to specify the location of the updates.img file that you want to apply during installation. The updates.img file can be derived from one of several sources.

Table C.4. updates.img file sources

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 inst.updates.


Updates from a disk image

Save an updates.img on a floppy drive or a USB key. This can be done only with an ext2 filesystem 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/fd0 with 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.img in the installation tree so that all installations can detect the .img file. The file name must be updates.img.

For NFS installs, save the file in the images/ directory, or in the RHupdates/ directory.


Use 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:

  • debug
  • info
  • warning
  • error
  • critical

The default value is info, which means that by default, the logging terminal displays messages ranging from info to critical.

Sends log messages to the syslog process on the specified host when the installation starts. You can use inst.syslog= only if the remote syslog process is configured to accept incoming connections.
Use the 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 org.fedoraproject.anaconda.log.0.

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.
Copies the stage 2 image in images/install.img into 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:port using 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.

Disables dmraid support.

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, dmraid or wipefs.

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.gpt boot option allows a GPT to be written to smaller disks.
Use the 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-labeled device 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 5 seconds. Use 0 seconds 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.

The method option is an alias for inst.repo.
Use nameserver instead of dns. Note that nameserver does not accept comma-separated lists; use multiple nameserver options instead.
netmask, gateway, hostname
The netmask, gateway, and hostname options are provided as part of the ip option.
A PXE-supplied BOOTIF option is used automatically, so there is no requirement to use ip=bootif.
Table C.5. Values for the ksdevice boot option

Not present



Ignored as this option is the same as the default behavior


Ignored as this option is the default if BOOTIF= is present


Replaced with ip=ibft. See ip for details


Replaced with BOOTIF=${MAC/:/-}


Replaced with bootdev

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
initramfs is completely non-interactive, so the askmethod and asknetwork options have been removed. Use inst.repo or specify the appropriate network options.
blacklist, nofirewire
The modprobe option now handles blocklisting kernel modules. Use modprobe.blacklist=<mod1>,<mod2>. You can blocklist the firewire module by using modprobe.blacklist=firewire_ohci.
The 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.
The inst.decorated option 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.
Use the inst.repo=nfs: option.
Use the console=ttyS0 option.
Use the inst.updates option.
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 initramfs.
Use the dracut option option.
Use the inst.ks=hd:<device> option.
For a remote display of the UI, use the inst.vnc option.
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.
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