System Booting

• BIOS loads MBR (Master Boot Record) from first boot device.
• MBR contains lilo(boot.b) code and absolute disk pointers to kernel(s).
• LILO loads selected kernel (or other boot program; like NT)
• Kernel loads and starts executing. Compiled-in drivers are run.
• Kernel modules are loaded as needed.
• The init program starts.
  • /etc/inittab.
    • /etc/rc.d/rc.sysinit
      • /etc/rc.d/rc.local
        • /etc/rc.d/rc.serial if exists
    • /etc/rc.d/rc runs contents of /etc/rc.d/rc[012345].d based on run level
• Programs to help place items in the /etc/rc.d/ directories. These are symlinks from /etc/rc.d/init.d
• chkconfig
  • based on SGI chkconfig
  • Just makes symlink from /etc/rc.d/init.d to /etc/rc.d/rcx.d/????
• ntsysv
  • menu type program
• just makes symlink
• System messages from the boot process are in /var/log/messages
• Serial console.
• /boot/
  • boot.0300 -- saved bootblock
  • kernel -- kernel-2.0.35
  • initrd
    • needed if scsi kernel modules are used
    • rebuild if kernel is rebuilt. It contains all of the modules that were recompiled. Needed because the scsi drivers need to be loaded before the scsi devices can be used. You cannot load them off of scsi disk because you do not have drivers that can access them yet. The old catch 22 problem.
    • mkinitrd <initrd-image-to be made> <kernel version>
      • kernel version is used to find the modules in /lib/modules/<kernel version>