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Booting, initializing, and virtualizing Linux - Coggle Diagram
- Booting, initializing, and virtualizing Linux
5.1. The boot process
The boot process
- The boot loader runs and determines which Linux kernel program to load
- The kernel program loads into memory, mounts the root partition and runs the initialization program
- Firmware starts, check the hardware and it looks for a boot loader program to run from a bootable device
- The initialization program starts the background programs required for the system to operate
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5.2. Firmware
The BIOS startup
Master Boot Record (MBR) informs how to find the boot loader program and is the first sector on the first hard drive partition on the system
Since the boot loader program must fit in one sector, , it can't do much
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The UEFI startup
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It specifies a a special disk partition called the EFI System Partition (ESP) that allows for any size of boot loader program
5.3. Boot loaders
GRUB legacy
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Example of referencing the second partition on the first hard drive: root (hd0,1)
Installing GRUB legacy
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Referencing the partition too: grub-install '(hd0,0)'
GRUB 2
grub.cfg
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menuentry "CenOS Linux" { [...] set root=(hd1,1) [...] }
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5.5. Stoping the system
Stopping the processes, shuts down the CPU, and sends signals to the hardware to power down: poweroff
Stopping the processes, shuts down the CPU, and then restarts the system: reboot
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Stopping the processes, shuts down the CPU, and sends signals to the hardware to power down:shutdown
5.6. Notifying the users
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Sends message to users logged into a tty terminal or who has a GUI terminal emulator open: /bin/wall or usr/bin/wall
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5.7. Virtual Machine
Hypervisors
Type 1: Runs directlyon the physical system. It is called a "bare-metal" hypervisor for this reason.
Type 2: Operates between its created VM (guest) and the physical system (host). It interacts with the host's OS. These VMS each have their own OS.
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