Friday, September 2, 2011

How your Linux Boots ?

This is the Normal boot process of a Linux Operating System in to your computer. Boot process takes place in 4 scenes with 4 main characters.

Scene 1
when the computer is switched on,it automatically invokes BIOS[a ROM chip embedded in the motherboard].The BIOS will start the processor and perform a POST[power on self test] to check whether the connected device are ready to use and are working properly. Once the POST is completes BIOS will jump to a specified location in the RAM and check for the booting device.The boot sector is always the first sector of the hard disk and BIOS will load the MBR into the memory.

Scene 2
Here the boot loader takes the control of the booting process.LILO or GRUB are the boot loaders commonly available. It will help the user to select various boot options.Depending on the boot option selected the kernel is loaded.

scene 3

After kernel is loaded the kernel will take the control of the booting process and it will initialize all the hardwares including I/O processors etc.kernel then creates a root device and mounts the partitions.

Scene 4
INIT is loaded