The Boot process

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The Boot process
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The Boot process
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Booting on a PC

• POST
• Hardware test may not run CPU ie fan not
  working
• CPU start-up
• Jumps to fixed location to execute BIOS code
• BIOS
• Initialises hardware allows user interaction
• Bootloader
• Allows selection of OS and parameters

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Booting with GRUB

• Grand Unified Bootloader
• Part of the GNU development
• Currently changing from GRUB1 to GRUB2
• Currently seen as the replacement for LILO

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GRUB

• 3 stage booting process
• Stages 1, 1.5 2
• GRUB can be file system aware
• Can ignore that stage
• Can run GRUB from the OS (LINUX)

MBR resident code
Stage 1
File system Aware code
Stage 1.5
Linux resident Kernel
Stage 2
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Why use GRUB?

• Although LILO works and has a huge Linux user
  base, many are changing to GRUB
• More robust
• Does use maps which can easily change
• Lower maintenance
• Dont need to run lilo/silo
• Easier maintenance
• Can run from OS
• More features/command line options
• Bash style shell