Due Date: May 4, 1999
These problems ask you to make small modifications to the MINIX kernel. You
will be modifying the kernel's source code, recompiling and assembling it,
using make(1) to link the various executable files, and then produce a
new MINIX boot "disk."
These programs require only rather minor modifications to MINIX. The key is
locating the current code that should be modified; surely, there are many
To receive credit for your solutions, show the TAs the modifications you have
made to the kernel source code. Also demonstrate your new kernel running
programs that show that your new kernel meets the requirements of the problem.
Think carefully to come up with programs that demonstrate your new kernel.
Submit a boot disk with your new Minix system to the homework box by the
deadline. Put your sources for your changes to the MINIX kernel, and the
program(s) you wish to run to demonstrate your new kernel, onto a second disk,
and submit that disk as well.
- Modify the MINIX kernel to record the number of open,
close, read, write,
exec, getpid, fork, stat, unlink, and
kill system calls each process makes.
That is, you will use an array, perhaps as part of the process table, to
record for each process how many times it has made a specific system call,
e.g., open. When a particular hot-key is depressed (you
pick the key), this array will be displayed. To convince yourself that the
kernel is functioning according to the requirement, run a program that will
make lots of system calls and show that they are being recorded. Remember to
initialize the array when the process begins
For details on the hot keys, look over the description on the bottom of page
- Modify the MINIX process table so that it contains a priority field
for each process. The priority of a newly created process is to be zero, and
the priority is to decrease by 1 each time the process loses the CPU -- whether
by having its quantum expire or when it makes a system call. When the
scheduler picks a process to run, it will pick the highest-priority process.
Pick a hot-key that when struck will print the priorities of all processes.
You will be asked to demonstrate that your new MINIX kernel properly modifies
priority and always schedules processes with highest priority. To do this, you
might want to have a number of long processes around, and then create a few
short processes and demonstrate that these get scheduled as you would expect.
Send email to
Department of Computer Science
University of California at Davis
Davis, CA 95616-8562
Page last modified on 4/22/99