Chapter 2, The Character of Operating Systems Video Solutions, Smartphone Operating System Concepts with Symbian OS: A Tutorial Guide

Problem 1

Consider the following services and classify them as taking place in the kernel or outside the kernel. Do this for both microkernel and hybrid kernel systems.
a. Opening and closing files
b. Writing to a register
c. Reading a memory cell
d. Receiving a text message
e. Playing a sound bite.

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Problem 2

Software interrupts are useful for many things. We discussed timers as an example of software interrupts. Think of other examples in a computer system of software interrupts. (Hint: Think of software interrupts as events.)

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Problem 3

With software interrupts, what form does the interrupt vector take? Where is it stored?

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Problem 4

Context-switching is expensive because of the 'context' that is switched. Try to identify as many parts of this context as you can.

Adam Conner

Numerade Educator

Problem 5

Often people think of 'protection' as 'security'. We discussed ways to protect user programs and the operating system from each other. In what ways could the protection mechanisms we discussed be a form of security?

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Problem 6

We gave a few examples of device $1 / O$ types. Can you develop more examples for each I/O type? Explain your answers.

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Problem 7

Which of the following operations should be done in the kernel as privileged mode?
a. Reading and writing files
b. Sending a text message
c. Taking a picture with the camera
d. Notifying a program about data received
e. Switching processes on the CPU
f. Reading from a memory cell.

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Problem 8

What would a system look like without a privileged mode? Could such an operating system be useful? How would it be possible to implement protection?

Adam Conner

Numerade Educator

Problem 9

Systems typically have multiple caches built into the hardware; we called them L1 and L2. Why is multilevel caching useful?

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Problem 10

Survey the concepts and structures we discussed in this chapter. In what ways would hardware be useful to help implement a specific structure? For example, how could hardware help with context-switching or memory protection?

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Problem 11

How would you classify a kernel that implemented the various forms of the OS/360 operating systems?

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Problem 12

As we discussed, Symbian OS uses two levels of kernel space operations: the executive call and the kernel-server request. Why would this be necessary? Why should executive calls be barred from creating objects in the kernel? (Hint: think about the usefulness of the servers in a microkernel.)

James Kiss

Numerade Educator

Problem 13

Symbian OS has an object-oriented design. Survey our discussion of Symbian OS and flag places where object orientation would complement the design strategies.

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Problem 14

Symbian OS is designed for use on smartphones. Consider a smartphone platform and identify the forms of communication that it would use. For each of these forms of communication, identify the type of device $\mathrm{I} / \mathrm{O}$ that could be used to implement that form.

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Problem 15

Consider your answer to the previous question. Must Symbian OS be a real-time operating system? Are there portions of system operation that do not have to operate in real time? How does the microkernel design of Symbian OS help reduce the need for real-time operation?

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