Review of OS Concepts

Kernel vs. User Mode

• Capabilities (power)
• Entering Kernel Mode (hardware)
• Entering Kernel Mode (software)

Purpose of OS

• Resource Management
• Abstraction
• Protected Access to Resources

Kernel Organization

• Monolithic
  • Historical use
  • Current use
• Layered
• Modularized
• Microkernel

Processes and Threads

Syncronization

• Critical Sections
• Hardware Support for Syncronization
  • Interrupts
  • TSB and friends (requires hardware-level sync!)
• Semaphores
• Monitors