Grub Configuration Guide

This document describes how to configure the GRUB boot loader for LadinOS kernel.

Overview

GRUB (Grand Unified Bootloader) is the default boot loader for LadinOS. It manages the boot process and allows selecting between multiple kernel versions or operating systems.

Key features for LadinOS:

Automatic detection of installed kernels
Support for custom boot parameters
Recovery mode options

Configuration Files

GRUB configuration in LadinOS is managed through the following files:

/boot/grub/grub.cfg - Main configuration file (auto-generated, do not edit directly)
/etc/default/grub - Global settings (edit this file for customizations)
/etc/grub.d/ - Scripts used to generate grub.cfg (advanced customization)

To add custom menu entries, create a new script in /etc/grub.d/ (e.g., 40_custom):

#!/bin/sh exec tail -n +3 $0 # This file provides an easy way to add custom menu entries. menuentry 'LadinOS (Custom Kernel)' --class ladinos { insmod ext2 set root='(hd0,1)' linux /boot/vmlinuz-custom root=/dev/sda1 ro quiet initrd /boot/initrd-custom }

Make the script executable:

chmod +x /etc/grub.d/40_custom

Kernel Parameters

Common kernel parameters for LadinOS:

ro - Mount root filesystem as read-only initially
rw - Mount root filesystem as read-write
quiet - Suppress most boot messages
debug - Enable kernel debugging output
init=/bin/systemd - Specify init system

To set permanent parameters, edit /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX="root=/dev/sda1"

Updating Grub

After making changes to configuration files, regenerate grub.cfg:

sudo update-grub

This command runs all scripts in /etc/grub.d/ and updates /boot/grub/grub.cfg.

Troubleshooting

Common issues and solutions:

Grub menu not appearing: Check GRUB_TIMEOUT in /etc/default/grub (set to 5 for 5-second delay)
Kernel panic on boot: Try adding nomodeset to kernel parameters
Changes not taking effect: Ensure you ran update-grub after editing files