Linux Journey system Boot process

CentOS 6.x version boot process 1. Press the power-on button and the motherboard reads the BIOS information; 2. Biso loads the CMOS information to find the startup item and reads the MBR3 of the first startup item. Depending on the settings of the MBR, the bootloader,6.x version is loaded using GRUB4. Grub reads the/boot/grub/menu.lst file to obtain the location of the kernel files Vmlinuz and INITRD 5. Read Vmlinuz and INITRD files 6 according to the configuration in the/boot/grub/menu.lst file. Unzip the initrd file in memory, generate the root directory, load the core Vmlinuz, start to detect the hardware with the core functionality, and load the driver. 7. Kernel Load driver releases the virtual file system and mounts the actual root file system, reads the hard disk file, calls the Init process to start system initialization 8. The init process reads the/etc/initab file for boot level (runlevel), calls the/etc/rc.d/rc.sysinit file to prepare the software operating environment (network, time zone, etc.) 9. According to the boot level read/etc/rc.d/rc[0-6].d/and/etc/sysconfig directory configuration file initialization related services, run rc.local Configure personal settings 10. Init runs the terminal emulator Mingetty to start the login program, waiting for the user to log in   the primary configuration file to use during the boot process/boot/grub/menu.lst/etc/rc.d/rc.sysinit/etc/rc.d/rc[ 0-6].d/*/etc/sysconfig/* centos 7.x version Start-up process 1. Press the power-on button and the motherboard reads the BIOS information; 2. Biso looks for the startup item based on the setup information and reads the MBR3 of the first startup item. Depending on the settings of the MBR, the bootloader,7.x version is loaded using GRUB24. GRUB2 read the/boot/grub2/grub.cfg file to get the location of the kernel file Vmlinuz and INITRD 5. Read Vmlinuz and INITRD files 6 according to the configuration in the/boot/grub2/grub.cfg file. Unzip the initrd file in memory, generate the root directory, load the core Vmlinuz, start to detect the hardware with the core functionality, and load the driver. 7. The kernel calls the SYSTEMD program to default.target the process to boot 8. SYSTEMD performing Sysinit.target initialization system and Basic.target preparing the operating system 9. Systemd Start MultiNative and server services under-user.target 10. SYSTEMD executes the/etc/rc.d/rc.local file under Multi-user.target 11. SYSTEMD implementation of Multi-user.target under the Getty.target and landing services. SYSTEMD perform graphical required services (graphical interface required)   main configuration files used during boot/etc/ modprobe.d/*.conf/etc/modules-load.d/*.conf/etc/sysconfig/*

Linux Journey system Boot process