1. Slide 5-1 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 5 Device Management

2. Slide 5-2 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Input/Output Devices Input Device Processor Output Device

3. Slide 5-3 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 The Device Driver Interface Device Interface … write(…); … Terminal Driver Terminal Driver Printer Driver Printer Driver Disk Driver Disk Driver Terminal Controller Terminal Controller Printer Controller Printer Controller Disk Controller Disk Controller

4. Slide 5-4 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Device Management Organization Application Process Application Process File Manager File Manager Device Controller Command Status Data Hardware Interface System Interface Device-Independent Device-Dependent

5. Slide 5-5 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Overlapping the Operation of a Device and the CPU Variable x Register Data on device... read(dev_I, %d, x); y = f(x)... Device dev_I Memory CPU... startRead(dev_I, %d, x);... While(stillReading()) ; y = f(x)...

6. Slide 5-6 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Polling I/O Read Operation read(device, …); Data Device Controller Command Status Data read function write function 1 234 5 Hardware Interface System Interface

7. Slide 5-7 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Interrupt-driven I/O Operation read(device, …); Data Device Controller Command Status Data read driver write driver 1 2 3 4 5 Hardware Interface System Interface Device Status Table Device Handler Device Handler Interrupt Handler Interrupt Handler 6 7 8a 8b 9

8. Slide 5-8 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Device Independent Function Call func i (…) Trap Table dev_func_i(devID, …) { // Processing common to all devices … switch(devID) { case dev0:dev0_func_i(…); break; case dev1:dev1_func_i(…); break; … case devM:devM_func_i(…); break; }; // Processing common to all devices … }

9. Slide 5-9 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Driver-Kernel Interface Drivers are distinct from main part of kernel Kernel makes calls on specific functions, drivers implement them Drivers use kernel functions for: –Device allocation –Resource (e.g., memory) allocation –Scheduling –etc. (varies from OS to OS)

10. Slide 5-10 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Reconfigurable Device Drivers Other Kernel services Other Kernel services Entry Points for Device j open(){…} read(){…} etc. System call interface Driver for Device j

11. Slide 5-11 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Handling Interrupts int read(…) { // Prepare for I/O save_state(J); outdev# // Done (no return) } Device driver J Device Controller Interrupt Handler void dev_handler(…) { get_state(J); //Cleanup after op signal(dev[j]); return_from_sys_call(); } Device interrupt handler J J Device status table

12. Slide 5-12 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Handling Interrupts(2) int read(…) { … outdev# // Return after interrupt wait(dev[J}); return_from_sys_call(); } Device driver J Device Controller Interrupt Handler void dev_handler(…) { //Cleanup after op signal(dev[j]); } Device interrupt handler J

13. Slide 5-13 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 The Pure Cycle Water Company Water CompanyCustomer Office Water Consumers Water Producer Delivering Water Returning the Empties

14. Slide 5-14 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Hardware Buffering Process Controller Data Device Process Controller B Device A Process Controller B Device A Unbuffered Process reads b i-1 Controller reads b i Process reads b i Controller reads b i+1

15. Slide 5-15 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Double Buffering in the Driver Process Controller B Device A Process Controller B Device A BABA Hardware Driver

16. Slide 5-16 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Circular Buffering From data producer To data consumer Buffer i Buffer j

17. Slide 5-17 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 A Generic Communications Device Generic Controller Generic Controller Local Device Local Device Communications Controller Communications Controller Device Cabling connecting the controller to the device Printer Modem Network Bus

18. Slide 5-18 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Rotating Media Track (Cylinder) Sector (a) Multi-surface Disk(b) Disk Surface(b) Cylinders Cylinder (set of tracks)

19. Slide 5-19 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Storage Device Magnetic Disk (SCSI) Controller Driver Get disk description Set SCSI parms read/write ops Interrupt hander SCSI API commands bits per byte etc. Device Driver API

20. Slide 5-20 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Serial Port Serial Device Serial Device Memory CPU Printer Terminal Modem Mouse etc.

21. Slide 5-21 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Adding a Modem Serial Device Serial Device Memory CPU Modem Phone Switched Telephone Network Dialing & connecting Convert analog voice to/from digital Convert bytes to/from bit streams Transmit/receive protocol

22. Slide 5-22 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Serial Communication Modem RS-232 Serial Device Device Driver Set UART parms read/write ops Interrupt hander Driver-Modem Protocol Dialing & connecting Convert analog voice to/from digital Convert bytes to/from bit streams Transmit/receive protocol

23. Slide 5-23 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Comm Device Comm Device Memory CPU Modem Phone Comm Device Comm Device Memory CPU Modem Phone Switched Telephone Network Exploiting the Phone Network Logical Communication

24. Slide 5-24 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 5 Data Networks Network Device Network Device Memory CPU Network Device Network Device Memory CPU Data Network Logical Communication Technology focus includes protocols and software (more on this later … Chapter 15 and beyond...)