18. Boot Code

• If ExtX contains bootable Linux kernel, then its partition can have boot code

  • (sometimes it doesn't -- see next slide.)

• Boot code knows exactly which blocks are allocated to the Linux kernel.

• Boot code loads kernel into memory during boot.

• Non-bootable ExtX file system will have no boot code.

• If exists, the boot code is in the 1,024 bytes before the superblock -- that is, in the first two sectors of the partition.

• The boot code is executed after control is passed to it from the Master Boot Record (MBR) program in disk sector zero.