BIOS-MBR-BOOT LOADER– KERNEL-INIT -RUN LEVEL
1) BIOS IT WILL LOAD THE MBR INTO THE MEMORY FROM THE BOOT SECTOR ( BOOT SECTOR IT WILL BE FLOPPY ,HARD DISK , CDROM. THESE BOOT LOAD PRIORITY IT WILL BE CHANGE FROM THE BIOS SETUP)
2)THEN BOOT LOADER IT WILL TAKE THE CONTROL OF THE SYSTEM FROM THE FOLLOWING FILE /ETC/LILO.CONF /ETC/GRUB.CONF (LILO IS MOST LINUX DISTRIBUTION DEFAULT BOOT LOADER) [LINUX IT WILL LOAD THE IMAGE WINDOWS IT WILL LOAD THE DOS].
3)IT WILL SHOW THE LIST OF OPERATING SYSTEM WHICH ONE NEED TO BOOT. IT WILL IDENTIFY WHICH KERNEL NEEDS TO BOOT.
SYSTEM STARTUB
LINUX LOADS THE KERNEL & INITIAL RAM DISK IMAGE INTO SYSTEM MEMORY TO BOOT THE SYSTEM .
4)THEN KERNEL RUN INIT (INITIALIZATION) PROGRAM ACCORDING TO THE /ETC/INITTAB.
UNDER THE /ETC/INITTAB FILE IT HAS RUN LEVEL SCRIPT
EXAMPLE : /ETC/RC.D/RC0.D
JUST LIKE IT HAS THE LINUX SIX RUN LEVEL
UNDER THE RUN LEVEL
IF FILE START WITH
K-SHUTDOWN SCRIPT
S-START UP SCRIPT
5)BASED ON THE DEFAULT RUN LEVEL IT WILL EXECUTED THE PROCESS.STUDY ABOUT RUN LEVEL REFER THESE LINK
IMPORTANT FILES FOR LINUX BOOT SEQUENCE
BOOT LOADER
/ETC/GRUB/GRUB.CONF
/ETC/LILO.CONF
SYSTEM INSTILLATION IT WILL REFER TO THE THE MOUNT PARTITION TABLE FROM THE /ETC/FSTAB FILE
RUN LEVEL IT WILL REFERS TO THE /ETC/INITTAB FILE
