Chapter 20. Boot Options

The Red Hat Enterprise Linux installation system includes a range of boot options for administrators, which modify the default behavior of the installation program by enabling (or disabling) certain functions. To use boot options, append them to the boot command line, as described in Section 20.1, “Configuring the Installation System at the Boot Menu”. Multiple options added to the boot line need to be separated by a single space.
There are two basic types of options described in this chapter:
  • Options presented as ending with an "equals" sign (=) require a value to be specified - they cannot be used on their own. For example, the inst.vncpassword= option must also contain a value (in this case, a password). The correct form is therefore inst.vncpassword=password. On its own, without a password specified, the option is invalid.
  • Options presented without the "=" sign do not accept any values or parameters. For example, the option forces Anaconda to verify the installation media before starting the installation; if this option is present, the check will be performed, and if it is not present, the check will be skipped.

20.1. Configuring the Installation System at the Boot Menu


The exact way to specify custom boot options is different on every system architecture. For architecture-specific instructions about editing boot options, see:
There are several different ways to edit boot options at the boot menu (that is, the menu which appears after you boot the installation media):
  • The boot: prompt, accessed by pressing the Esc key anywhere in the boot menu. When using this prompt, the first option must always specify the installation program image file to be loaded. In most cases, the image can be specified using the linux keyword. After that, additional options can be specified as needed.
    Pressing the Tab key at this prompt will display help in the form of usable commands where applicable. To start the installation with your options, press the Enter key. To return from the boot: prompt to the boot menu, restart the computer and boot from the installation media again.
  • The > prompt on BIOS-based AMD64 and Intel 64 systems, accessed by highlighting an entry in the boot menu and pressing the Tab key. Unlike the boot: prompt, this prompt allows you to edit a predefined set of boot options. For example, if you highlight the entry labeled Test this media & install Red Hat Enterprise Linux 7.0, a full set of options used by this menu entry will be displayed on the prompt, allowing you to add your own options.
    Pressing Enter will start the installation using the options you specified. To cancel editing and return to the boot menu, press the Esc key at any time.
  • The GRUB2 menu on UEFI-based AMD64 and Intel 64 systems. If your system uses UEFI, you can edit boot options by highlighting an entry and pressing the e key. When you finish editing, press F10 or Ctrl+X to start the installation using the options you specified.
In addition to the options described in this chapter, the boot prompt also accepts dracut kernel options. A list of these options is available as the dracut.cmdline(7) man page.


Boot options specific to the installation program always start with inst. in this guide. Currently, this prefix is optional, for example, resolution=1024x768 will work exactly the same as inst.resolution=1024x768. However, it is expected that the inst. prefix will be mandatory in future releases.

Specifying the Installation Source

Specifies the installation source - that is, a location where the installation program can find the images and packages it requires. For example:
The target must be either:
  • an installable tree, which is a directory structure containing the installation program's images, packages and repodata as well as a valid .treeinfo file
  • a DVD (a physical disk present in the system's DVD drive)
  • an ISO image of the full Red Hat Enterprise Linux installation DVD, placed on a hard drive or a network location accessible from the installation system
This option allows for the configuration of different installation methods using different formats. The syntax is described in the table below.

Table 20.1. Installation Sources

Installation source Option format
Any CD/DVD drive inst.repo=cdrom
Specific CD/DVD drive inst.repo=cdrom:device
Hard Drive inst.repo=hd:device:/path
HTTP Server inst.repo=http://host/path
HTTPS Server inst.repo=https://host/path
FTP Server inst.repo=ftp://username:password@host/path
NFS Server inst.repo=nfs:[options:]server:/path [a]
[a] This option uses NFS protocol version 3 by default. To use a different version, add +nfsvers=X to options.


In previous releases of Red Hat Enterprise Linux, there were separate options for an installable tree accessible by NFS (the nfs option) and an ISO image located on an NFS source (the nfsiso option). In Red Hat Enterprise Linux 7, the installation program can automatically detect whether the source is an installable tree or a directory containing an ISO image, and the nfsiso option is deprecated.
Disk device names may be specified using the following formats:
  • Kernel device name, for example /dev/sda1 or sdb2
  • File system label, for example LABEL=Flash or LABEL=RHEL7
  • 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 (" ").
Specifies the location of the installation program runtime image to be loaded. The syntax is the same as in Specifying the Installation Source. This option expects a path to a directory containing a valid .treeinfo file; the location of the runtime image will be read from this file if found. If a .treeinfo file is not available, Anaconda will try to load the image from LiveOS/squashfs.img.


By default, the inst.stage2= boot option is used on the installation media and set to a specific label (for example, inst.stage2=hd:LABEL=RHEL7\x20Server.x86_64). If you modify the default label of the file system containing the runtime image, or if using a customized procedure to boot the installation system, you must ensure this option is set to the correct value.
If you need to perform a driver update during the installation, use the inst.dd= option. It can be used multiple times. The location of a driver RPM package can be specified using any of the formats detailed in Specifying the Installation Source. With the exception of the inst.dd=cdrom option, the device name must always be specified. For example:
Using this option without any parameters (only as inst.dd) will prompt the installation program to ask you for a driver update disk with an interactive menu.
For more information about driver updates during the installation, see Chapter 4, Updating Drivers During Installation on AMD64 and Intel 64 Systems for AMD64 and Intel 64 systems and Chapter 9, Updating Drivers During Installation on IBM Power Systems for IBM Power Systems servers.

Kickstart Boot Options

Gives the location of a Kickstart file to be used to automate the installation. Locations can be specified using any of the formats valid for inst.repo. See Specifying the Installation Source for details.
If you only specify a device and not a path, the installation program will look for the Kickstart file in /ks.cfg on the specified device. If you use this option without specifying a device, the installation program will use the following:
In the above example, next-server is the DHCP next-server option or the IP address of the DHCP server itself, and filename is the DHCP filename option, or /kickstart/. If the given file name ends with the / character, ip-kickstart is appended. For example:

Table 20.2. Default Kickstart File Location

DHCP server address Client address Kickstart file location
Additionally, starting with Red Hat Enterprise Linux 7.2, the installer will attempt to load a Kickstart file named ks.cfg from a volume with a label of OEMDRV if present. If your Kickstart file is in this location, you do not need to use the inst.ks= boot option at all.
Adds headers to outgoing HTTP requests with the MAC addresses of all network interfaces. For example:
X-RHN-Provisioning-MAC-0: eth0 01:23:45:67:89:ab
This can be useful when using inst.ks=http to provision systems.
Adds a header to outgoing HTTP requests. This header will contain the system's serial number, read from /sys/class/dmi/id/product_serial. The header has the following syntax:
X-System-Serial-Number: R8VA23D

Console, Environment and Display Options

This kernel option specifies a device to be used as the primary console. For example, to use a console on the first serial port, use console=ttyS0. This option should be used along with the inst.text option.
You can use this option multiple times. In that case, the boot message will be displayed on all specified consoles, but only the last one will be used by the installation program afterwards. For example, if you specify console=ttyS0 console=ttyS1, the installation program will use ttyS1.
Disables access to the root shell during the installation. This is useful with automated (Kickstart) installations - if you use this option, a user can watch the installation progress, but they cannot interfere with it by accessing the root shell by pressing Ctrl+Alt+F2.
Sets the language to be used during the installation. Language codes are the same as the ones used in the lang Kickstart command as described in Section 24.3.2, “Kickstart Commands and Options”. On systems where the system-config-language package is installed, a list of valid values can also be find in /usr/share/system-config-language/locale-list.
Configures 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 parameter can be any of the following:

Table 20.3. Valid Values for the inst.geoloc Option

Disable geolocation inst.geoloc=0
Use the Fedora GeoIP API inst.geoloc=provider_fedora_geoip
Use the GeoIP API inst.geoloc=provider_hostip
If this option is not specified, Anaconda will use provider_fedora_geoip.
Specifies the keyboard layout to be used by the installation program. Layout codes are the same as the ones used in the keyboard Kickstart command as described in Section 24.3.2, “Kickstart Commands and Options”.
Forces the installation program to run in text mode instead of graphical mode. The text user interface is limited, for example, it does not allow you to modify the partition layout or set up LVM. When installing a system on a machine with a limited graphical capabilities, it is recommended to use VNC as described in Enabling Remote Access.
Forces the installation program to run in command line mode. This mode does not allow any interaction, all options must be specified in a Kickstart file or on the command line.
Forces the installation program to run in graphical mode. This mode is the default.
Specifies 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 lowest supported resolution is 800x600.
Specifies that the machine being installed onto does not have any display hardware. In other words, this option prevents the installation program from trying to detect a screen.
Specifies the name of the X driver to be used both during the installation and on the installed system.
Tells the installation program to use the frame buffer X driver instead of a hardware-specific driver. This option is equivalent to inst.xdriver=fbdev.
Blacklists (completely disables) one or more drivers. Drivers (mods) disabled using this option will be prevented from loading when the installation starts, and after the installation finishes, the installed system will keep these settings. The blacklisted drivers can then be found in the /etc/modprobe.d/ directory.
Use a comma-separated list to disable multiple drivers. For example:
By default, sshd is only automatically started on IBM System z, and on other architectures, sshd is not started unless the inst.sshd option is used. This option prevents sshd from starting automatically on IBM System z.
Starts the sshd service during the installation, which allows you to connect to the system during the installation using SSH and monitor its progress. For more information on SSH, see the ssh(1) man page and the corresponding chapter in the Red Hat Enterprise Linux 7 System Administrator's Guide. By default, sshd is only automatically started on IBM System z, and on other architectures, sshd is not started unless the inst.sshd option is used.


During the installation, the root account has no password by default. You can set a root password to be used during the installation with the sshpw Kickstart command as described in Section 24.3.2, “Kickstart Commands and Options”.
Enables or disables the Kdump configuration screen (add-on) in the installer. This screen is enabled by default; use inst.kdump_addon=off to disable it. Note that disabling the add-on will disable the Kdump screens in both the graphical and text-based interface as well as the %addon com_redhat_kdump Kickstart command.

Network Boot Options

Initial network initialization is handled by dracut. This section only lists some of the more commonly used options; for a complete list, see the dracut.cmdline(7) man page. Additional information on networking is also available in Red Hat Enterprise Linux 7 Networking Guide.
Configures one or more network interfaces. To configure multiple interfaces, you can use the ip option multiple times - once for each interface. If multiple interfaces are configured, you must also use the option rd.neednet=1, and you must specify a primary boot interface using the bootdev option, described below. Alternatively, you can use the ip option once, and then use Kickstart to set up further interfaces.
This option accepts several different formats. The most common are described in Table 20.4, “Network Interface Configuration Formats”.

Table 20.4. Network Interface Configuration Formats

Configuration Method Option format
Automatic configuration of any interface ip=method
Automatic configuration of a specific interface ip=interface:method
Static configuration ip=ip::gateway:netmask:hostname:interface:none
Automatic configuration of a specific interface with an override [a] ip=ip::gateway:netmask:hostname:interface:method:mtu
[a] Brings up the specified 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 parameter. All parameters are optional; only specify the ones you wish to override and automatically obtained values will be used for the others.
The method parameter can be any the following:

Table 20.5. Automatic Interface Configuration Methods

Automatic configuration method Value
DHCP dhcp
IPv6 DHCP dhcp6
IPv6 automatic configuration auto6
iBFT (iSCSI Boot Firmware Table) ibft


If you use a boot option which requires network access, such as inst.ks=http://host:/path, without specifying the ip option, the installation program will use ip=dhcp.


To connect automatically to an iSCSI target, a network device for accessing the target needs to be activated. The recommended way to do so is to use ip=ibft boot option.
In the above tables, the ip parameter specifies the client's IP address. IPv6 addresses can be specified by putting them in square brackets, for example, [2001:DB8::1].
The gateway parameter is the default gateway. IPv6 addresses are accepted here as well.
The netmask parameter is the netmask to be used. This can either be 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.
Specifies the address of the name server. This option can be used multiple times.
You must use the option rd.neednet=1 if you use more than one ip option. Alternatively, to set up multiple network interfaces you can use the ip once, and then set up further interfaces using Kickstart.
Specifies the boot interface. This option is mandatory if you use more than one ip option.
Assigns a given interface name to a network device with a given MAC address. Can be used multiple times. The syntax is ifname=interface:MAC. For example:


Using the ifname= option is the only supported way to set custom network interface names during installation.
Specifies the DHCP vendor class identifier. The dhcpd service will see 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 maximum amount of time to wait for network connectivity before timing out and continuing the installation process even if network connectivity is not present.
Sets up a Virtual LAN (VLAN) device on a specified interface with a given name. The syntax is vlan=name:interface. For example:
The above will set up a VLAN device named vlan5 on the em1 interface. The name can take the following forms:

Table 20.6. VLAN Device Naming Conventions

Naming scheme Example
VLAN_PLUS_VID vlan0005
DEV_PLUS_VID em1.0005.
Set up a bonding device with the following syntax: bond=name[:slaves][:options]. Replace name with the bonding device name, slaves 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.
Using this option without any parameters will assume bond=bond0:eth0,eth1:mode=balance-rr.
Set up a team device with the following syntax: team=master:slaves. Replace master with the name of the master team device and slaves with a comma-separated list of physical (ethernet) devices to be used as slaves in the team device. For example:

Advanced Installation Options

If this option is specified, the installer will use the kexec system call at the end of the installation, instead of performing a reboot. This loads the new system immediately, and bypasses the hardware initialization normally performed by the BIOS or firmware.


Due to the complexities involved with booting systems using kexec, it cannot be explicitly tested and guaranteed to function in every situation.
When kexec is used, device registers (which would normally be cleared during a full system reboot) might stay filled with data, which could potentially create issues for some device drivers.
Force the installation program to install partition information into a GUID Partition Table (GPT) instead of a Master Boot Record (MBR). This option is meaningless on UEFI-based systems, unless they are in BIOS compatibility mode.
Normally, BIOS-based systems and UEFI-based systems in BIOS compatibility mode will attempt to use the MBR schema for storing partitioning information, unless the disk is 232 sectors in size or larger. Most commonly, disk sectors are 512 bytes in size, meaning that this is usually equivalent to 2 TiB. Using this option will change this behavior, allowing a GPT to be written to disks smaller than this.
See Section, “MBR and GPT Considerations” for more information about GPT and MBR, and Section A.1.4, “GUID Partition Table (GPT)” for more general information about GPT, MBR and disk partitioning in general.
Configure the system for multilib packages (that is, to allow installing 32-bit packages on a 64-bit AMD64 or Intel 64 system) and install packages specified in this section as such.
Normally, on an AMD64 or Intel 64 system, only packages for this architecture (marked as x86_64) and packages for all architectures (marked as noarch would be installed. When you use this option, packages for 32-bit AMD or Intel systems (marked as i686) will be automatically installed as well if available.
This only applies to packages directly specified in the %packages section. If a package is only installed as a dependency, only the exact specified dependency will be installed. For example, if you are installing package bash which depends on package glibc, the former will be installed in multiple variants, while the latter will only be installed in variants specifically required.
By default, SELinux operates in permissive mode in the installer, and in enforcing mode in the installed system. This option disables the use of SELinux in the installer and the installed system entirely.


The selinux=0 and inst.selinux=0 options are not the same. The selinux=0 option disables the use of SELinux in the installer and the installed system, whereas inst.selinux=0 disables SELinux only in the installer. By default, SELinux is set to operate in permissive mode in the installer, so disabling it has little effect.
This option, introduced in Red Hat Enterprise Linux 7.3, controls which Kickstart files and installation logs are saved to the installed system. It can be especially useful to disable saving such data when performing OEM operating system installations, or when generating images using sensitive resources (such as internal repository URLs), as these resources might otherwise be mentioned in kickstart files, or in logs on the image, or both. Possible values for this option are:
input_ks - disables saving of the input Kickstart file (if any).
output_ks - disables saving of the output Kickstart file generated by Anaconda.
all_ks - disables saving of both input and output Kickstart files.
logs - disables saving of all installation logs.
all - disables saving of all Kickstart files and all installation logs.
Multiple values can be combined as a comma separated list, for example: input_ks,logs
This option controls the usage of zRAM swap during the installation. It creates a compressed block device inside the system RAM and uses it for swap space instead of the hard drive. This allows the installer to essentially increase the amount of memory available, which makes the installation faster on systems with low memory.
By default, swap on zRAM is enabled on systems with 2 GiB or less RAM, and disabled on systems with more than 2 GiB of memory. You can use this option to change this behavior - on a system with more than 2 GiB RAM, use inst.zram=1 to enable it, and on systems with 2 GiB or less memory, use inst.zram=0 to disable this feature.

Enabling Remote Access

The following options are necessary to configure Anaconda for remote graphical installation. See Chapter 22, Installing Using VNC for more details.
Specifies that the installation program's graphical interface should be run in a VNC session. If you specify this option, you will need to connect to the system using a VNC client application to be able to interact with the installation program. VNC sharing is enabled, so multiple clients can connect to the system at the same time.


A system installed using VNC will start in text mode by default.
Sets a password on the VNC server used by the installation program. Any VNC client attempting to connecting to the system will have to provide the correct password to gain access. For example, inst.vncpassword=testpwd will set the password to testpwd. The VNC password must be between 6 and 8 characters long.


If you specify an invalid password (one that is too short or too long), you will be prompted to specify a new one by a message from the installation program:
VNC password must be six to eight characters long.
Please enter a new one, or leave blank for no password.

Connect to a listening VNC client at a specified host and port once the installation starts. The correct syntax is inst.vncconnect=host:port, where host is the address to the VNC client's host, and port specifies which port to use. The port parameter is optional, if you do not specify one, the installation program will use 5900.

Debugging and Troubleshooting

Specifies the location of the updates.img file to be applied to the installation program runtime. The syntax is the same as in the inst.repo option - see Table 20.1, “Installation Sources” for details. In all formats, if you do not specify a file name but only a directory, the installation program will look for a file named updates.img.
Specifies the minimum level for messages to be logged on a terminal. This only concerns terminal logging; log files will always contain messages of all levels.
Possible values for this option from the lowest to highest level are: debug, info, warning, error and critical. The default value is info, which means that by default, the logging terminal will display messages ranging from info to critical.
Once the installation starts, this option sends log messages to the syslog process on the specified host. The remote syslog process must be configured to accept incoming connections. For information on how to configure a syslog service to accept incoming connections, see the Red Hat Enterprise Linux 7 System Administrator's Guide.
Specifies a virtio port (a character device at /dev/virtio-ports/name) to be used for forwarding logs. The default value is org.fedoraproject.anaconda.log.0; if this port is present, it will be used.

20.1.1. Deprecated and Removed Boot Options

Deprecated Boot Options

Options in this list are deprecated. They will still work, but there are other options which offer the same functionality. Using deprecated options is not recommended and they are expected to be removed in future releases.


Note that as Section 20.1, “Configuring the Installation System at the Boot Menu” describes, options specific to the installation program now use the inst. prefix. For example, the vnc= option is considered deprecated and replaced by the inst.vnc= option. These changes are not listed here.
Configured the installation method. Use the inst.repo= option instead.
In NFS installations, specified that the target is an ISO image located on an NFS server instead of an installable tree. The difference is now detected automatically, which means this option is the same as inst.repo=nfs:server:/path.
Configured the Domain Name Server (DNS). Use the nameserver= option instead.
netmask=, gateway=, hostname=, ip=, ipv6=
These options have been consolidated under the ip= option.
Select network device to be used at early stage of installation. Different values have been replaced with different options; see the table below.

Table 20.7. Automatic Interface Configuration Methods

Value Current behavior
Not present Activation of all devices is attempted using dhcp, unless the desired device and configuration is specified by the ip= option or the BOOTIF option.
ksdevice=link Similar to the above, with the difference that network will always be activated in the initramfs, whether it is needed or not. The supported rd.neednet dracut option should be used to achieve the same result.
ksdevice=bootif Ignored (the BOOTID= option is used by default when specified)
ksdevice=ibft Replaced with the ip=ibft dracut option
ksdevice=MAC Replaced with BOOTIF=MAC
ksdevice=device Replaced by specifying the device name using the ip= dracut option.


When performing a Kickstart installation, booting from local media and having the Kickstart file on local media as well, the network will not be initialized. This means that any other Kickstart options requiring network access, such as pre-installation or post-installation scripts accessing a network location, will cause the installation to fail. This is a known issue; see BZ#1085310 for details.
To work around this issue, either use the ksdevice=link boot option, or add the --device=link option to the network command in your Kickstart file.
Used to disable specified drivers. This is now handled by the modprobe.blacklist= option.
Disabled support for the FireWire interface. You can disable the FireWire driver (firewire_ohci) by using the modprobe.blacklist= option instead:

Removed Boot Options

The following options are removed. They were present in previous releases of Red Hat Enterprise Linux, but they cannot be used anymore.
askmethod, asknetwork
The installation program's initramfs is now completely non-interactive, which means that these options are not available anymore. Instead, use the inst.repo= to specify the installation method and ip= to configure network settings.
This option forced Anaconda to use the /dev/ttyS0 console as the output. Use the console=/dev/ttyS0 (or similar) instead.
Specified the location of updates for the installation program. Use the inst.updates= option instead.
essid=, wepkey=, wpakey=
Configured wireless network access. Network configuration is now being handled by dracut, which does not support wireless networking, rendering these options useless.
Used in the past to configure additional low-level network settings. All network settings are now handled by the ip= option.
Allowed you to debug the loader. Use rd.debug instead.
Verified the installation media before starting the installation. Replaced with the option.
Specified a 3.5 inch diskette as the Kickstart file source. These drives are not supported anymore.
Configured a remote display. Replaced with the inst.vnc option.
Added UTF8 support when installing in text mode. UTF8 support now works automatically.
Used to disable IPv6 support in the installation program. IPv6 is now built into the kernel so the driver cannot be blacklisted; however, it is possible to disable IPv6 using the ipv6.disable dracut option.
Upgrades are done in a different way in Red Hat Enterprise Linux 7. For more information about upgrading your system, see Chapter 26, Upgrading Your Current System.
Used to configure Virtual LAN (802.1q tag) devices. Use the vlan= dracut option instead.