This system uses EFI, therefore the Red Hat Upgrade Tool will install the grub2-efi and shim packages during the upgrade. Create the /etc/default/grub file before running redhat-upgrade-tool to ensure the correct grub2 configuration. Misconfiguration might make the system unbootable. As an example, the /etc/defaults/grub file can look like this:

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="(insert the storage and other kernel parameters here, for example:) rd.lvm.lv=rhel/root crashkernel=auto  rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet"
GRUB_DISABLE_RECOVERY="true"

