General process of Linux Startup

It is always mysterious about how a computer starts. First, you should first understand the related concepts: Hard Disk composition: hard disk consists of multiple sectors and multiple cylinders. For hard disks, the sector is very important, the first sector is the most important, this part stores two important information: the primary boot partition, partition table. Primary boot partition: Also known as MBR, It is the location where the Boot Loader (that is, the kernel) is loaded. The size is 500 bytes (or 446 bytes ). Partition Table: This table records the status of the entire hard disk partition. The size is (64 bytes ). It consists of four parts, each of which records the basic information about this partition, with a size of 16 bytes. (In addition, this is why/dev/sba1 -- 4 is left to the primary partition and extended partition when the hard disk is mounted, while the logical partition starts from/dev/sb5, whether the primary partition and the extended partition are 4 fast ). Www.2cto.com BIOS: In most cases, we need to enter the BIOS and set the boot content. This program is written to the motherboard. Next, let's talk about the Linux system startup process: After the computer starts, it first reads the program on the motherboard, that is, the BIOS. It reads the information about user settings and then reads the storage devices of the relevant devices, for example, the hard disk reads the content of the first sector (MBR). At this time, the BIOS ends and the baton is handed over to MBR. The main function of MBR is to load the Kernel File, the implementation of this function is a short and tough program (boot loader) in MBR, because it was mentioned during system installation, so it can identify the file format of the kernel file in the hard disk. The next step is about the kernel file. It will complete the task of loading the operating system. Www.2cto.com flowchart: computer power start -------> BIOS --------> MBR (boot loader) -------> Kernel File --------> other software supplements: boot loader has the following tasks. provides menus. for multiple systems, different options are provided, which is also an important feature of Multi-boot. 2. Load the Kernel File. 3. Transfer another loader. If multiple loaders exist, the loader will be handed over to other loaders. Author: fjsm20Linux