Table of Contents
Abstract
In this chapter we have made a lifelong friend with a
beautifully simple microkernel called MINIX. We solve an exercise of Tanenbaum
and Woodhull's operating systems book,
first with the modification of a part of PCB (Process Control Block) defined in proc.h,
then with the creation of a new system call.
First of all we setup a MINIX system and we show how to compile the MINIX kernel.
„Re 2: your job is being a professor and researcher: That's one hell of a good excuse for some of the brain-damages of minix.”
Eric Steven Raymond (esr) changed the term
free software to open source in
The
Cathedral and the Bazaar in 1998. More than ten years back,
the MINIX had been released in 1987, so obviously it was not open
source.
GNU GPL
It may be noted that the first version of GNU GPL was released in 1989 and the first Linux had already been licensed under GNU GPL version 2, released in 1991.
At the beginning of the informatics profession, the C source codes of UNIX systems could have been used in university courses, but it lasted only a short period of time due to UNIXs had become a very valuable product quickly and then it was no longer possible to teach the operating systems in its C source form. The MINIX was born in this environment. The purpose of it was specifically to allow the usage of the source code of a UNIX-like operating system in education again.
From this aspect, the MINIX can be regarded as a pioneer of open source operating systems and, ultimately, we can say that the open source was brought into existence by the closing of the source code [OS3].
The IPC (Inter-Process Communication) determines a communication method in which programs can exchange data with each other. There are several IPC mechanisms, from pipes through anonymous, local and network sockets to using shared memory (from these methods semaphore arrays and the shared memory will be used in the third case studies). The MINIX IPC is based on the message passing. The massage passing takes place between two appropriately synchronised (by the rendezvous principle) processes, so we would not buffer the messages [OS], [OS3], as shown in the following figures.
