Running on the bare metal with GeekOS

Abstract

Undergraduate operating systems courses are generally taught using one of two approaches: abstract or concrete. In the abstract approach, students learn the concepts underlying operating systems theory, and perhaps apply them using user-level threads in a host operating system. In the concrete approach, students apply concepts by working on a real operating system kernel. In the purest manifestation of the concrete approach, students implement operating system projects that run on real hardware.GeekOS is an instructional operating system kernel which runs on real hardware. It provides the minimum functionality needed to schedule threads and control essential devices on an x86 PC. On this foundation, we have developed projects in which students build processes, semaphores, a multilevel feedback scheduler, paged virtual memory, a filesystem, and inter-process communication. We use the Bochs emulator for ease of development and debugging. While this approach (tiny kernel run on an emulator) is not new, we believe GeekOS goes further towards the goal of combining realism and simplicity than previous systems have.

Teaching operating systems as how computers work

“…This is a deliberate decision, as the goal of these exercises is to illustrate particular issues and mechanisms, not to teach students how to work with a large body of systems code. The largest amount of "scaffolding" required for the CS 5600 assignments is 600 lines of actual code (including headers) for the file system assignment, compared to 4500 lines for project0 in GeekOS [3,4], or over 7000 for just the scheduler in a recent Linux kernel.…”

An experimental laboratory environment for teaching embedded operating systems

“…There have been simulated RISC operating systems [16], and educational systems that execute on bare CISC hardware [4,11]. To our knowledge, Embedded XINU is the first educational O/S targetted to a RISC architecture embedded in a system-on-a-chip platform.…”

The pintos instructional operating system kernel

“…Approaches to teaching OS courses generally fall along two axes: whether the treatment of the material is abstract or concrete [13], and whether they adopt an internal or external perspective [8]. An abstract approach discusses algorithms and techniques used in operating systems and may include partial implementation or simulation exercises, whereas a Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page.…”

“…Although Pintos follows in the tradition of instructional operating systems such as TOY OS [9], Nachos [6], OS/161 [12], and GeekOS [13], PortOS [2], BLITZ [16], JOS [1], or Yalnix [1], we believe that it is unique in two aspects. First, Pintos runs on both real hardware and in emulated and simulated environments.…”