recap: architecture support in os - bowdoin collegesbarker/teaching/courses/os/14fall/lectur… ·...

Sean Barker

Recap: Architecture Support in OS

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OS Service Hardware Support

Protection Kernel/user mode, protected instructions, base/limit registers

Interrupts Interrupt vectors

System calls Trap instructions and trap vectors

I/O InterruptsScheduling, error recovery,

accounting Timer

Synchronization Atomic instructions

Virtual memory Translation look-aside buffers

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Today: OS Services and Structure

! System call implementation

! Organization and components of an OS

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System Calls

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Making a System Call

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user mode

kernel mode

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Example System Calls

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System Call Implementation

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OS Architecture: Mac OS X

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OS Architecture: Windows 8

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Monolithic Kernel Design

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Layered OS Design

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User programs

Device drivers

Virtual memory

I/O channel

CPU scheduler

Hardware

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Microkernel Design

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Mac OS X - hybrid approach

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Modules

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Summary

! System calls as interface to the OS

! OS design approaches• Monolithic• Layered• Microkernels• Modules

! Tradeoffs: simplicity vs. performance

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