3.3. Systems with UEFI firmware

menuentry - Defines the title of the entry. It is specified in single or double quotes (' or "). You can use the --class option to group menu entries into different classes, which can then be styled differently by using GRUB2 themes.

linuxefi - Defines the kernel that boots (/images/pxeboot/vmlinuz from the example) and the other additional options, if any.

You can customize these options to change the behavior of the boot entry.

One of the notable options is inst.ks=, which allows you to specify a location of a Kickstart file. You can place a Kickstart file on the boot ISO image and use the inst.ks= option to specify its location; for example, you can place a kickstart.ks file into the image’s root directory and use inst.ks=hd:LABEL=RHEL-10-0-BaseOS-x86_64:/kickstart.ks.

You can also use dracut options which are listed on the dracut.cmdline(7) man page on your system.

set timeout - Determines how long is the boot menu displayed before the default menu entry is automatically used. The default value is 60, which means the menu is displayed for 60 seconds. Setting this value to -1 disables the timeout completely.

submenu - A submenu block allows you to create a sub-menu and group some entries under it, instead of displaying them in the main menu. The Troubleshooting submenu in the default configuration contains entries for rescuing an existing system.

The title of the entry is in single or double quotes (' or ").

The submenu block contains one or more menuentry definitions as described above, and the entire block is enclosed in curly braces ({}) For example:

submenu 'Submenu title' {
  menuentry 'Submenu option 1' {
    linuxefi /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 nomodeset quiet
    initrdefi /images/pxeboot/initrd.img
  }
  menuentry 'Submenu option 2' {
    linuxefi /images/pxeboot/vmlinuz inst.stage2=hd:LABEL=RHEL-10-0-BaseOS-x86_64 inst.rescue quiet
    initrdefi /images/pxeboot/initrd.img
  }
}