what is a kernal, bootloader?

Question

hello friends, i need to know about boot loader and kernel in deep from its basic. i search the google and got a lot of links... but i need to find the good ones. if you pals have any docs or video or htmls share with me.....

thanks in advance

Answer 1

Kernel is the core code component of the operating system. It is used to interact with the hardware and provides an interface for application software. Read wikipedia here for detailed info.

Details vary from platform to platform, but in general the following steps represent the boot process.

• When the computer starts, the BIOS performs Power-On-Self-Test (POST) and initial device discovery and initialization, since the OS’ boot process may rely on access to disks, screens, keyboards, etc.
• Next, the first sector of the boot disk, the MBR (Master Boot Record) is read into a fixed memory location and executed. This sector contains a small (512-byte) program that loads a standalone program called boot from the boot device, usually an IDE or SCSI disk.
• The boot program first copies itself to a fixed high memory address to
  free up low memory for the operating system. Once moved, boot reads the root directory of the boot device.

• To do this, it must understand the file system and directory format, which is the case with some bootloaders such as GRUB BootloaderGRandUnified.

• Other popular bootloaders, such as Intel’s LILO, do not rely on any specific filesystem. Instead, they need a block map, and low-level addresses, which describe physical sectors, heads, and cylinders, to find the relevant sectors to be loaded.

• Then it reads in the operating system kernel and jumps to it. At this point, boot has finished its job and the kernel is running.