Boot Process

Question 1

boot process order

Answer 1

Firmware phase
bootloader phase
kernel phase
initialization phase

Question 2

what is the primary job of the the bootloader program?

Answer 2

find the Linux kernel code in the /boot file system, decompress it, load it into memory based on the config defined in /boot/grub2/grub.cfg or /boot/efi for UEFI

Question 3

what is the kernel

Answer 3

central program of the operating system, providing access to hardware and system services

Question 4

explain the kernel phase

Answer 4

extracts Initial RAM disk (initrd) found in /boot
mounts initrd to /sysroot temporarily
Loads necessary modules from initrd image
allows access to physical disks and partitions
loads drivers to support boot process
unmount initrd and mount actual root file system on /
executes systemd with PID 1

Question 5

where is the default GRUB2 config file

Answer 5

/etc/default/grub

must run grub2-mkconfig afterwards

Question 6

change default system boot timeout

Answer 6

edit /etc/default/grub file
GRUB_TIMEOUT=8

execute grub2-mkconfig
sudo grub2-mkconfig -o /boot/grub2/grub.cfg

reboot

Question 7

which files are the kernel in /boot

Answer 7

vmlinuz, initramfs, config, and System.map

Question 8

where is cpu info and memory info stored

Answer 8

/proc/cpuinfo

/proc/meminfo