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OS161

OS/161 is a teaching operating system, that is, a simplified system used for teaching undergraduate operating systems classes. It is BSD-like in feel and has more "reality" than most other teaching OSes; while it runs on a simulator it has the structure and design of a larger system.

More info here: http://os161.eecs.harvard.edu

Modify the kernel

  1. Create a file in kern/main/yourfile.c and write a function

  2. Modify kern/main/main.c entering a call to your function

  3. In test.h:

    #include "opt-yourfile.h" //(opt-optname.h)
Insert a prototype of your function

  4. Modify kern/conf/conf.kern inserting the new file (#Startup and initialization):

     defoption yourfile
 optfile   yourfile   main/yourfile.c

  5. Generate in kern/conf a new file (for example YOURFILE)

     It can be a copy of DUMBVM adding a new line: "options yourfile"

  6. Finally do the make of the kernel:

       In kern/conf
       ./config YOURFILE
       
   In kern/compile/YOURFILE
       bmake depend
       bmake
       bmake install

Writing a new system call

  1. In kern/arch/mips/syscall/syscall.c there is switch case in which you can menage the system calls

  2. To menage a system call it's necessary an integer code. See:

    kern/include/kern/syscall.h

  3. Create your system call in kern/syscall/my_syscalls.c

  4. Modify kern/include/syscall.h adding a prototype of the syscall function

  5. Modify kern/conf/conf.kern inserting the new file (#System call layer):

    file syscall/my_syscalls.c

  6. Finally do the make of the kernel

     In kern/conf
   ./config DUMBVM
   
 In kern/compile/DUMBVM
     bmake depend
     bmake
     bmake install