Boot Process Flashcards
The “ boot process “ includes ?
\+ Power On \+ BIOS \+ Master Boot Record \+ Boot Loader (GRUB) \+ Kernel (Linux OS) \+ Initial RAM Disk \+ /sbin/init \+ Command Shell using getty \+ X Windows System (GUI)
BIOS stands for ?
Basic Input Output System
BIOS does ?
+ Initialize hardwares like screen and keyboard
+ Tests the main memory (POST)
BIOS is stored on ?
ROM chip
MBR stands for ?
Master Boot Record
MBR is ?
A small bit of computer code that the BIOS executes to start the boot process.
MBR does ?
When fully executed, this code transfers control to the boot program stored on the bootable partition to search for the boot loaders (GRUB) and loads it into RAM memory.
Boot Loaders are stored ?
+ First block of the bootable medium.
+ A specific partition of the bootable medium.
Boot Loaders serve as ?
Mediator between the hardware and the operating system.
Two stages of Boot Loaders ?
+ Load the main memory.
+ Load the kernel of the operating system & Initialize the RAM disk.
Initial RAM Disk ?
A scheme for loading the root filesystem into memory.
” initramfs “ is ?
A method to initialize RAM disk (load the root filesystem into memory).
” initramfs “ includes ?
Programs & Binary files
” udev “ is responsible for ?
Figuring out which device is present, locating the device drivers and load it into memory.
” mount “ program is used for ?
Instruct the OS that the root filesystem is mounted properly and ready for used.
/sbin/init (or init) is responsible for ?
+ Start the processes
+ Keep the system running
+ Shut it down cleanly
+ Manager of all non-kernel processes
The root filesystem is loaded by ?
The kernel
” init “ is ?
The initial process, followed by other processes to get the system running.
Difference between “ systemd “ and “ init “ ?
+ Similarity: First process that starts at boot
+ Difference: Start up faster than “ init “
” systemd “ is faster than “ init “ because ?
Replaces a serialized of steps with aggressive parallelization techniques, meaning multiple services are initiated simultaneously.
