Laboratory 3

Due Date: March 10, 2000	Points: 100

The first problem asks you to make very small modifications to MINIX.  You will be modifying the kernel (actually I/
O driver) server source code, recompiling and assembling them, using make to link the various executable files, and 
then produce a new MINIX boot disk.  All of this is quite straightforward, as described in the handout on recompiling 
MINIX.

The key is locating the current code that should be modified;  surely, there are many acceptable solutions.  You are 
advised to avoid too many recompilations; you are advised to think through the modifications you wish to make 
before doing the recompilation.

To receive credit for your solutions, you must submit a new boot disk and a disk with your programs; they should be 
placed in the homework box by the due date.  Make an appointment to demonstrate your new version of the operating 
system using the test programs you have produced.  During the demonstration, the TAs might ask you to run the pro-
gram with different data or they might ask you questions on the code.

1.	Modify the MINIX disk driver to print the number of blocks in the disk I/O queue whenever a request to read or 
write the disk is made.

2.	Write a user-level program diskloc that takes a single file name as an argument and prints out the number of disk 
blocks in the named file and the location of the blocks on the disk, in order. Create a large file to demonstrate 
your program handles singly-indirect and doubly-indirect blocks.
Hint: Your program will need to be setuid to root. It will have to open the raw disk device, locate the list of 
inodes, and proceed from there.