Persistent kernel boot parameters are configured in two primary ways on modern systems like Oracle Linux. The /etc/default/grub file is used for global settings; parameters added to the GRUBCMDLINELINUX directive in this file are applied to all kernel menu entries after regenerating the main configuration.

Additionally, systems using the Boot Loader Specification (BLS), such as Oracle Linux 8 and later, manage boot entries via individual configuration files located in /boot/loader/entries/. Each file corresponds to a specific kernel and contains an options line where kernel-specific boot parameters are defined, ensuring they are persistent for that entry.

B. Changes made at the GRUB command-line interface are temporary and apply only to the immediate boot session; they are not persistent across reboots.

D. Editing parameters from the GRUB 2 boot menu (by pressing 'e') is a non-persistent method that only affects the current boot.

1. Oracle Linux 9 Documentation

Managing Core System Configuration

Chapter 3. Working with the GRUB 2 Boot Loader

Section 3.3. Modifying Kernel Boot Parameters: This section details the two methods for making persistent changes. It states

"To apply a change to all boot entries

you would edit the /etc/default/grub file... On systems where the Boot Loader Specification (BLS) is enabled... each kernel has its own configuration file in the /boot/loader/entries directory."

2. Red Hat Enterprise Linux 8 Documentation

Configuring basic system settings

Chapter 26. Managing the boot loader

Section 26.5. Adding kernel boot parameters: This official documentation (for the upstream distribution of Oracle Linux) explicitly confirms both correct methods: "To add kernel boot parameters to all menu entries

use the /etc/default/grub file. To add kernel boot parameters to a single menu entry

use the /boot/loader/entries/ files." It also clarifies that temporary changes are made by editing the boot menu.