First, the system boot process:
1 , POST (BIOS): hardware self-test, a separate battery ( button cells ), generally can be prevented to forget basic input output system (BIOS), password buckle down and connected to the positive and negative discharge about 8 seconds password expiration. (1, 2 add self-test, hardware initialization, 3, booting the operating system) generally fault condition, 1, blue 2, sound
2 , the MBR boot: the first hard disk track 0 is called the MBR first sector, i.e. the Boot Master the Record, the master boot record, its size is 512 bytes, the main task is to find a boot program and loads in secondary boot program on the hard disk partition. Find the active partition by the partition table, and in the active partition of the secondary boot loader is read into memory to run.
3, GRUB: secondary boot loader was the main function is to load the linux kernel, secondary bootstrap (boot loader) will boot the operating system. When the machine boots its operating system, BIOS will read the medium on the top of the guide 512 bytes (the master boot record, i.e., master boot record, MBR). In a single boot record MBR can only store an operating system, so the problem will arise when multiple operating systems, the need for more flexible boot loader
Secondary boot loader will be up and running in memory. The system reads the memory grub configuration information (usually menu.lst or grub.lst) there will be GRUB graphical interface, allowing users to choose what kind of kernel loads and in accordance with the configuration information to start a different operating system. (Linux guide)
4, after loading the kernel (Kernel) the user to select the kernel to load, the secondary boot loader (GRUB) will be based on / boot / grub information .conf profile set, read from the Linux partition / boot / where kernel image, then the kernel image is loaded into memory and passes control to the Linux kernel. (Executable binary file)
5, the init process is initialized after the kernel is loaded, the program is first run / sbin / init (become a user process), the program reads / etc / inittab configuration file, init according to / etc / inittab configuration file to execute the appropriate script for system initialization, such as setting up the keyboard, fonts, load modules, network settings, etc. in fact, / etc / inittab file the most important role is to set the run level of Linux. (The first is a system process, the parent of all processes) (PID is always 1)