Nachos II: User Programs

Tom Kelliher, CS 318

Mar. 23, 1998

Announcements: Nachos threads grades.

From last time: Disk operation.

Outline: Idea, directories, compiling, experiment.

Assignment: For Friday, implement exec as a print string call.

Nachos User Programs

Idea

1. Protect the MIPS engine. How?

2. Support multiple address spaces. Address spaces not contiguous.

3. Time slice. Instrument.

4. Write a shell, utility programs.

Important Directories

1. machine

2. thread

3. bin

4. test

5. userprog

Compiling

1. coff2noff

2. A user program.

3. nachos

4. Running the user program.

A Small Test

1. Tracing a system call:
   1. syscall.h

   2. start.s

   3. exception.cc

2. Using exec to print a string:
   1. How is the parameter passed?

   2. What address space?

   3. Incrementing the PC. Subtle problems.

   4. See StartProcess in progtest.cc to see skeletal exec.