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The main content of this article is "introduction to the boot process of Linux system". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Next let the editor to take you to learn the "introduction to the boot process of Linux system"!

Press the power button until the welcome page comes out, and what linux does in total can be done in five steps.

1. BIOS power-on self-test:

Power-on self-test, detect hardware equipment. Then search for bootable devices that are active in the order above cmos. It can be optical drive, floppy disk, USB, etc.

2. Load the master boot loader (MBR):

The master bootstrapper is a 512-byte image. Contains a little bit of machine code and a small partition.

The task of the master bootstrap is to find and load the secondary bootstrap on the hard disk partition. Find the active partition through the partition table, and read the secondary boot loader in the active partition into memory to run.

3. Load the secondary boot logger (GRUB)

The secondary boot loader simply loads the linux kernel.

After the end of the previous phase, the second boot loader will run in memory. A GRUB graphical interface appears, allowing the user to choose which kernel to load.

4. Linux kernel image:

After the user selects the kernel to load, the secondary boot loader (GRUB) reads the Linux kernel image from the partition where / boot/grub.conf resides based on the information set in the / boot/ configuration file, then loads the kernel image into memory and gives control to the Linux kernel.

After the linux kernel gained control, it began to mind its own business.

1), detection hardware

2) extract yourself and install the necessary drivers

3), initialize the file system-related virtual device, LVM or RAID

4) Mount the root file system and hang it under the root directory

5) after completion, linux loads the init program in the process space, and it's init's turn to do the work.

5. Init process

Init is the initiator and controller of all processes, and all processes are derived from it.

After the init process gains control, it executes the / etc/rc.d/rc.sysinit script, sets environment variables, network, starts swap, checks and mounts the file system, and performs other initialization work according to the code inside.

At this point, the linux startup is complete.

Let's sum up a little bit:

First, the BIOS power-on self-test, then load the primary boot loader, secondary boot loader, and finally the linux kernel image, and then hand over control to the init process to complete the initialization work.

What is the swap partition?

Similar to virtual memory in windows systems, memory in swap is used when physical memory is insufficient.

At this point, I believe that everyone on the "Linux system boot process introduction" have a deeper understanding, might as well to the actual operation of it! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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