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Chapter 5. Optional: Customizing boot options

When you are installing RHEL on x86_64 or ARM64 architectures, you can edit the boot options to customize the installation process based on your specific environment.

5.1. Boot options

You can append multiple options separated by space to the boot command line. Boot options specific to the installation program always start with inst. The following are the available boot options:

Options with an equals "=" sign
You must specify a value for boot options that use the = symbol. For example, the inst.vncpassword= option must contain a value, in this example, a password. The correct syntax for this example is inst.vncpassword=password.
Options without an equals "=" sign
This boot option does not accept any values or parameters. For example, the rd.live.check option forces the installation program to verify the installation media before starting the installation. If this boot option is present, the installation program performs the verification and if the boot option is not present, the verification is skipped.

You can customize boot options for a particular menu entry in the following ways:

  • On BIOS-based systems: Press the Tab key and add custom boot options to the command line. You can also access the boot: prompt by pressing the Esc key but no required boot options are preset. In this scenario, you must always specify the Linux option before using any other boot options. For more information, see Editing the boot: prompt in BIOS
  • On UEFI-based systems: Press the e key and add custom boot options to the command line. When ready press Ctrl+X to boot the modified option.

For more information, see Editing boot options for the UEFI-based systems

5.2. Editing the boot: prompt in BIOS

When using the boot: prompt, the first option must always specify the installation program image file that you want to load. In most cases, you can specify the image using the keyword. You can specify additional options according to your requirements.

Prerequisites

  • You have created bootable installation media (USB, CD or DVD).
  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. With the boot menu open, press the Esc key on your keyboard.
  2. The boot: prompt is now accessible.
  3. Press the Tab key on your keyboard to display the help commands.
  4. Press the Enter key on your keyboard to start the installation with your options. To return from the boot: prompt to the boot menu, restart the system and boot from the installation media again.

Additional resources

  • dracut.cmdline(7) man page on your system

5.3. Editing predefined boot options using the > prompt

On BIOS-based AMD64 and Intel 64 systems, you can use the > prompt to edit predefined boot options.

Prerequisites

  • You have created bootable installation media (USB, CD or DVD).
  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. From the boot menu, select an option and press the Tab key on your keyboard. The > prompt is accessible and displays the available options.
  2. Optional: To view a full set of options, select Test this media and install RHEL 8.

  3. Append the options that you require to the > prompt.

    For example, to enable the cryptographic module self-checks mandated by the Federal Information Processing Standard (FIPS) 140, add fips=1: 

    >vmlinuz initrd=initrd.img inst.stage2=hd:LABEL=RHEL-9-5-0-BaseOS-x86_64 rd.live.check quiet fips=1
  4. Press Enter to start the installation.
  5. Press Esc to cancel editing and return to the boot menu.

5.4. Editing boot options for the UEFI-based systems

You can edit the GRUB boot menu on UEFI-based systems during a RHEL installation to customize parameters. This allows configuring specific settings ensuring the installation meets their requirements.

Prerequisites

  • You have created bootable installation media (USB, CD or DVD).
  • You have booted the installation from the media, and the installation boot menu is open.

Procedure

  1. From the boot menu window, select the required option and press e.
  2. On UEFI systems, the kernel command line starts with linuxefi. Move the cursor to the end of the linuxefi kernel command line.

  3. Edit the parameters as required. For example, to enable the cryptographic module self-checks mandated by the Federal Information Processing Standard (FIPS) 140, add fips=1: 

    linuxefi /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-9-4-0-BaseOS-x86_64 rd.live.\
check quiet fips=1
  4. When you finish editing, press Ctrl+X to start the installation using the specified options.

5.5. Updating drivers during installation

You can update drivers during the Red Hat Enterprise Linux installation process. Updating drivers is completely optional. Do not perform a driver update unless it is necessary. Ensure you have been notified by Red Hat, your hardware vendor, or a trusted third-party vendor that a driver update is required during Red Hat Enterprise Linux installation.

5.5.1. Overview

Red Hat Enterprise Linux supports drivers for many hardware devices but some newly-released drivers may not be supported. A driver update should only be performed if an unsupported driver prevents the installation from completing. Updating drivers during installation is typically only required to support a particular configuration. For example, installing drivers for a storage adapter card that provides access to your system’s storage devices.

Warning

Driver update disks may disable conflicting kernel drivers. In rare cases, unloading a kernel module may cause installation errors.

5.5.2. Types of driver update

Red Hat, your hardware vendor, or a trusted third party provides the driver update as an ISO image file. Once you receive the ISO image file, choose the type of driver update.

Types of driver update

Automatic
In this driver update method; a storage device (including a CD, DVD, or USB flash drive) labeled OEMDRV is physically connected to the system. If the OEMDRV storage device is present when the installation starts, it is treated as a driver update disk, and the installation program automatically loads its drivers.
Assisted
The installation program prompts you to locate a driver update. You can use any local storage device with a label other than OEMDRV. The inst.dd boot option is specified when starting the installation. If you use this option without any parameters, the installation program displays all of the storage devices connected to the system, and prompts you to select a device that contains a driver update.
Manual
Manually specify a path to a driver update image or an RPM package. You can use any local storage device with a label other than OEMDRV, or a network location accessible from the installation system. The inst.dd=location boot option is specified when starting the installation, where location is the path to a driver update disk or ISO image. When you specify this option, the installation program attempts to load any driver updates found at the specified location. With manual driver updates, you can specify local storage devices, or a network location (HTTP, HTTPS or FTP server). You can use both inst.dd=location and inst.dd simultaneously, where location is the path to a driver update disk or ISO image. In this scenario, the installation program attempts to load any available driver updates from the location and also prompts you to select a device that contains the driver update.
Note

Initialize the network using the ip= option when loading a driver update from a network location.

Limitations

On UEFI systems with the Secure Boot technology enabled, all drivers must be signed with a valid certificate. Red Hat drivers are signed by one of Red Hat’s private keys and authenticated by its corresponding public key in the kernel. If you load additional, separate drivers, verify that they are signed.

5.5.3. Preparing a driver update

This procedure describes how to prepare a driver update on a CD and DVD.

Prerequisites

  • You have received the driver update ISO image from Red Hat, your hardware vendor, or a trusted third-party vendor.
  • You have burned the driver update ISO image to a CD or DVD.
Warning

If only a single ISO image file ending in .iso is available on the CD or DVD, the burn process has not been successful. See your system’s burning software documentation for instructions on how to burn ISO images to a CD or DVD.

Procedure

  1. Insert the driver update CD or DVD into your system’s CD/DVD drive, and browse it using the system’s file manager tool.
  2. Verify that a single file rhdd3 is available. rhdd3 is a signature file that contains the driver description and a directory named rpms, which contains the RPM packages with the actual drivers for various architectures.

5.5.4. Performing an automatic driver update

This procedure describes how to perform an automatic driver update during installation.

Prerequisites

  • You have placed the driver update image on a standard disk partition with an OEMDRV label or burnt the OEMDRV driver update image to a CD or DVD. Advanced storage, such as RAID or LVM volumes, may not be accessible during the driver update process.
  • You have connected a block device with an OEMDRV volume label to your system, or inserted the prepared CD or DVD into your system’s CD/DVD drive before starting the installation process.

Procedure

  • When you complete the prerequisite steps, the drivers load automatically when the installation program starts and installs during the system’s installation process.

5.5.5. Performing an assisted driver update

This procedure describes how to perform an assisted driver update during installation.

Prerequisites

  • You have connected a block device without an OEMDRV volume label to your system and copied the driver disk image to this device, or you have prepared a driver update CD or DVD and inserted it into your system’s CD or DVD drive before starting the installation process.
Note

If you burn an ISO image file to a CD or DVD but it does not have the OEMDRV volume label, you can use the inst.dd option with no arguments. The installation program provides an option to scan and select drivers from the CD or DVD. In this scenario, the installation program does not prompt you to select a driver update ISO image. Another scenario is to use the CD or DVD with the inst.dd=location boot option; this allows the installation program to automatically scan the CD or DVD for driver updates. For more information, see Performing a manual driver update.

Procedure

  1. From the boot menu window, press the Tab key on your keyboard to display the boot command line.
  2. Append the inst.dd boot option to the command line and press Enter to execute the boot process.
  3. From the menu, select a local disk partition or a CD or DVD device. The installation program scans for ISO files, or driver update RPM packages.

  4. Optional: Select the driver update ISO file.

    This step is not required if the selected device or partition contains driver update RPM packages rather than an ISO image file, for example, an optical drive containing a driver update CD or DVD.

  5. Select the required drivers.

    1. Use the number keys on your keyboard to toggle the driver selection.
    2. Press c to install the selected driver. The selected driver is loaded and the installation process starts.

5.5.6. Performing a manual driver update

This procedure describes how to perform a manual driver update during installation.

Prerequisites

  • You have placed the driver update ISO image file on a USB flash drive or a web server and connected it to your computer.

Procedure

  1. From the boot menu window, press the Tab key on your keyboard to display the boot command line.
  2. Append the inst.dd=location boot option to the command line, where location is a path to the driver update. Typically, the image file is located on a web server, for example, http://server.example.com/dd.iso, or on a USB flash drive, for example, /dev/sdb1. It is also possible to specify an RPM package containing the driver update, for example http://server.example.com/dd.rpm.
  3. Press Enter to execute the boot process. The drivers available at the specified location are automatically loaded and the installation process starts.

Additional resources

5.5.7. Disabling a driver

This procedure describes how to disable a malfunctioning driver.

Prerequisites

  • You have booted the installation program boot menu.

Procedure

  1. From the boot menu, press the Tab key on your keyboard to display the boot command line.

  2. Append the modprobe.blacklist=driver_name boot option to the command line.

    Replace driver_name with the name of the driver or drivers you want to disable, for example: 

    modprobe.blacklist=ahci

    Drivers disabled using the modprobe.blacklist= boot option remain disabled on the installed system and appear in the /etc/modprobe.d/anaconda-blacklist.conf file.

  3. Press Enter to execute the boot process.
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