nachos.userprog
Class UserKernel

java.lang.Object
  nachos.machine.Kernel
      nachos.threads.ThreadedKernel
          nachos.userprog.UserKernel

Direct Known Subclasses:

VMKernel

public class UserKernel
extends ThreadedKernel

A kernel that can support multiple user processes.

Field Summary

static SynchConsole

console Globally accessible reference to the synchronized console.

Fields inherited from class nachos.threads.ThreadedKernel

alarm, fileSystem, scheduler

Fields inherited from class nachos.machine.Kernel

kernel

Constructor Summary

UserKernel()
Allocate a new user kernel.

Method Summary

static UserProcess	currentProcess() Returns the current process.
void	exceptionHandler() The exception handler.
void	initialize(String[] args) Initialize this kernel.
void	run() Start running user programs, by creating a process and running a shell program in it.
void	selfTest() Test the console device.
void	terminate() Terminate this kernel.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

console

public static SynchConsole console

Globally accessible reference to the synchronized console.

Constructor Detail

UserKernel

public UserKernel()

Allocate a new user kernel.

Method Detail

initialize

public void initialize(String[] args)

Initialize this kernel. Creates a synchronized console and sets the processor's exception handler.

Overrides:

initialize in class ThreadedKernel

selfTest

public void selfTest()

Test the console device.

Overrides:

selfTest in class ThreadedKernel

currentProcess

public static UserProcess currentProcess()

Returns the current process.

Returns:

the current process, or null if no process is current.

exceptionHandler

public void exceptionHandler()

The exception handler. This handler is called by the processor whenever a user instruction causes a processor exception.

When the exception handler is invoked, interrupts are enabled, and the processor's cause register contains an integer identifying the cause of the exception (see the exceptionZZZ constants in the Processor class). If the exception involves a bad virtual address (e.g. page fault, TLB miss, read-only, bus error, or address error), the processor's BadVAddr register identifies the virtual address that caused the exception.

run

public void run()

Start running user programs, by creating a process and running a shell program in it. The name of the shell program it must run is returned by Machine.getShellProgramName().

Overrides:

run in class ThreadedKernel

See Also:

Machine.getShellProgramName()

terminate

public void terminate()

Terminate this kernel. Never returns.

Overrides:

terminate in class ThreadedKernel