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


  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


  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


  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 to see skeletal exec.

Thomas P. Kelliher
Mon Mar 23 10:15:52 EST 1998
Tom Kelliher