DOCSLIB.ORG

A Multiserver User-Space Unikernel for a Distributed Virtualization System

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Multiserver User-Space Unikernel for a Distributed Virtualization System A Multiserver User-space Unikernel for a Distributed Virtualization System Pablo Pessolani Departamento de Ingeniería en Sistemas de Información Facultad Regional Santa Fe, UTN Santa Fe, Argentina [email protected] Abstract— Nowadays, most Cloud applications are developed application components began to be deployed in Containers. using Service Oriented Architecture (SOA) or MicroService Containers (and similar OS abstractions such as Jails [7] and Architecture (MSA). The scalability and performance of them Zones [8]) are isolated execution environments or domains is achieved by executing multiple instances of its components in in user-space to execute groups of processes. Although different nodes of a virtualization cluster. Initially, they were Containers share the same OS, they provide enough security, deployed in Virtual Machines (VMs) but, they required enough performance and failure isolation. As Containers demand computational, memory, network and storage resources to fewer resources than VMs [9], they are a good choice to hold an Operating System (OS), a set of utilities, libraries, and deploy swarms. the application component. By deploying hundreds of these Another option to reduce resource requirements is to use application components, the resource requirements increase a the application component embedded in a Unikernel [10, lot. To minimize them, usually small OSs with small memory footprint are used. Another way to reduce the resource 11]. A Unikernel is defined as “specialized, single-address- requirements is integrating the application components in a space machine image constructed by using library operating Unikernel. This article proposes a Unikernel called MUK, system” [12]. A Unikernel is a technology which integrates based on a multiserver OS, to be used as a tool to integrate monolithically network, storage, and file systems services Cloud application components. MUK was built to run in user- with the application component resulting in a single space of a Distributed Virtualization System. Both technologies executable code. This way of building an environment to run facilitate the scattering of application components in a the application optimizes resource usage because only those virtualization cluster keeping the isolation properties and services that the application requires are integrated. minimal attack surface of a Unikernel. Therefore, the size of the resulting executable code, memory footprint and the application attack surface are reduced to a Keywords: virtualization, multiserver, middleware minimum. Those facts improve application security, and make application components easily distributable, replicable I. INTRODUCTION and deployable. It is unlikely that the application component embedded Nowadays, there is a need to build and to deploy into a Unikernel will be completely autonomous. Probably, it distributed applications to satisfy the performance needs of needs to communicate with other components running within Cloud information systems. They must be able to manipulate other Unikernels, and with external servers such as storage big data volumes (sounds, videos, photographs, documents, servers, file servers, logging-servers, database servers, key- etc.) in huge and complex databases. Most of these Cloud value servers, etc. A provider-class Cloud application must applications are developed using the SOA [1] or MSA [2] coordinate the actions among its components and with the methodologies. Both software architectures, consist of external servers to provide fault tolerance and replicated factoring a monolithic application into multiple components services. Peer to peer and group communications, leader that communicate with each other through some standardized election mechanisms, fault detection, distributed locking, protocol (such as SOAP [3]), with a weak coupling between etc., are requirements to coordinate actions among them. distributed components. All of these are complex services The application scalability and performance is achieved which must be considered in the application design and by deploying multiple instances of its components in development stages and in the application-Unikernel build. different nodes of a virtualization cluster (usually called This article presents a Unikernel called MUK, based on a "swarms"). Initially, Virtual Machines (VMs) were used, but multi-server user-space OS instead of a Library OS. As its they required enough computational, memory, network and components (servers) are autonomous by definition, the storage resources to hold a complete Operating System (OS), integration with the application is facilitated. The chosen OS its utilities, libraries, and the application component. When used as a base to build MUK was Minix Over Linux (MoL) deploying a swarm of VMs, the resource needs increase [13], a user-space Minix branch which run as a set of Linux proportionally. To reduce that demand, OSs with small processes. Minix is a POSIX-compliant OS, and because memory footprint are often used. MoL is a port of it to user-space, it is compliant too. As Later, as management tools such as Docker [4], MUK is the Unikernel version of MoL, it keeps the POSIX- Kubernetes [5], Mesos [6] (among others) were improved, compliance which allows it to execute legacy applications Instead of running the application on the hosts-OS, a under its environment. This feature represents an important VOS (Virtual Operating Systems) [15] is needed to improve advantage over some other Unikernels which provide their security and fault isolation and provide a greater variety of own non-compliance APIs forcing developers to port their options for applications. The DVS enables the execution of legacy applications. multiple instances of different VOS each one executing in its MUK runs inside a Distributed Container of a Distributed own DC. A subset of nodes is allocated for each DC, but Virtualization System (DVS) [14]. A Distributed Container they can share the nodes between several DCs (Fig. 1). This covers several related Linux Containers scattered on nodes of higher degree of granularity of resource allocation allows a a virtualization cluster. The Unikernel and DVS technologies better use of the infrastructure and provides greater elasticity facilitate the distribution of application components as and efficiency. swarms across the nodes of a DVS cluster. A DVS provides MUK and its integrated application components, several A. DVS Architecture services required by distributed applications such as The main components of the DVS architecture model are location-transparent IPC, a Group Communication System (Fig. 2): (GCS), fault detection, replication, leader election mechanisms, easy deployment and management, etc. All Generic Applications - A Generic Applications - B these features are the platform requirements to develop and DC A Guest DVOS - A Guest DVOS - B DC B to deploy elastic, high availability, high performance, Container-1 Container-2 Container-3 Container-4 Distributed Virtualization distributed Cloud application. Distributed Virtualization Kernel (DVK) The rest of this article is organized as follows. Section II Management System (DVMS) refers to related works and background technologies. Section Host OS - 1 Host OS - 2 Host OS - 3 III describes the architecture of MoL as a Unikernel (MUK) and the design and implementation of its prototype. Partial performance evaluation results of the prototype are reported Node 1 Node 2 Node 3 in section IV and finally, Section V presents conclusions, in- Figure 2. Distributed Virtualization System architecture model. progress works, and future research projects. 1) Distributed Virtualization Kernel (DVK): It is the II. RELATED WORKS AND BACKGROUND TECHNOLOGIES core software layer that integrates the resources of the The most commonly adopted virtualization technologies cluster, manages and limits the resources assigned to each are VMs and Containers as isolated execution environments. DC. It provides interfaces for low-level protocols and Both are partitions of a physical computer, so that their services, which can be used to build a VOS, such as IPC, computing resources are limited by the latter. The architecture model of a DVS [14] is based on several GCS, synchronization, replication, locking, leader election, Virtualization and DOS [15, 16] technologies getting the fault detection, mutual exclusion, performance parameter benefits of both worlds. Due to its features, it is a good sensing, processes migration mechanism, etc. choice to offer high performance provider-class Cloud 2) Distributed Virtualization Management System (DVMS): services. In this sense, it presents attractive features for It is the software layer that allows the DVS administrator to Cloud service providers such as high availability, replication, both manage and monitor the resources of the cluster. elasticity, load balancing and process migration. In a DVS, 3) Container: It is a host-OS abstraction which provides an the administrator can build execution domains, called isolated environment to run the components of a VOS. A set Distributed Containers (DC), which can be extended beyond of related Containers makes up a DC. the limits of a physical machine or cluster node (Fig. 1). 4) Distributed Container (DC): It is a set of single Containers, each one being set up by the DVMS in the host- OS of each node. There is one DC per VOS, and a DC can span from one to all nodes. Only processes belonging to the same DC can communicate transparently between them
Load more

Recommended publications
  • What Is LLVM? and a Status Update
    What is LLVM? And a Status Update. Approved for public release Hal Finkel Leadership Computing Facility Argonne National Laboratory Clang, LLVM, etc. ✔ LLVM is a liberally-licensed(*) infrastructure for creating compilers, other toolchain components, and JIT compilation engines. ✔ Clang is a modern C++ frontend for LLVM ✔ LLVM and Clang will play significant roles in exascale computing systems! (*) Now under the Apache 2 license with the LLVM Exception LLVM/Clang is both a research platform and a production-quality compiler. 2 A role in exascale? Current/Future HPC vendors are already involved (plus many others)... Apple + Google Intel (Many millions invested annually) + many others (Qualcomm, Sony, Microsoft, Facebook, Ericcson, etc.) ARM LLVM IBM Cray NVIDIA (and PGI) Academia, Labs, etc. AMD 3 What is LLVM: LLVM is a multi-architecture infrastructure for constructing compilers and other toolchain components. LLVM is not a “low-level virtual machine”! LLVM IR Architecture-independent simplification Architecture-aware optimization (e.g. vectorization) Assembly printing, binary generation, or JIT execution Backends (Type legalization, instruction selection, register allocation, etc.) 4 What is Clang: LLVM IR Clang is a C++ frontend for LLVM... Code generation Parsing and C++ Source semantic analysis (C++14, C11, etc.) Static analysis ● For basic compilation, Clang works just like gcc – using clang instead of gcc, or clang++ instead of g++, in your makefile will likely “just work.” ● Clang has a scalable LTO, check out: https://clang.llvm.org/docs/ThinLTO.html 5 The core LLVM compiler-infrastructure components are one of the subprojects in the LLVM project. These components are also referred to as “LLVM.” 6 What About Flang? ● Started as a collaboration between DOE and NVIDIA/PGI.
    [Show full text]
  • A DSL for Resource Checking Using Finite State Automaton-Driven Symbolic Execution Code
    Open Comput. Sci. 2021; 11:107–115 Research Article Endre Fülöp and Norbert Pataki* A DSL for Resource Checking Using Finite State Automaton-Driven Symbolic Execution https://doi.org/10.1515/comp-2020-0120 code. Compilers validate the syntactic elements, referred Received Mar 31, 2020; accepted May 28, 2020 variables, called functions to name a few. However, many problems may remain undiscovered. Abstract: Static analysis is an essential way to find code Static analysis is a widely-used method which is by smells and bugs. It checks the source code without exe- definition the act of uncovering properties and reasoning cution and no test cases are required, therefore its cost is about software without observing its runtime behaviour, lower than testing. Moreover, static analysis can help in restricting the scope of tools to those which operate on the software engineering comprehensively, since static anal- source representation, the code written in a single or mul- ysis can be used for the validation of code conventions, tiple programming languages. While most static analysis for measuring software complexity and for executing code methods are designed to detect anomalies (called bugs) in refactorings as well. Symbolic execution is a static analy- software code, the methods they employ are varied [1]. One sis method where the variables (e.g. input data) are inter- major difference is the level of abstraction at which the preted with symbolic values. code is represented [2]. Because static analysis is closely Clang Static Analyzer is a powerful symbolic execution related to the compilation of the code, the formats used engine based on the Clang compiler infrastructure that to represent the different abstractions are not unique to can be used with C, C++ and Objective-C.
    [Show full text]
  • SMT-Based Refutation of Spurious Bug Reports in the Clang Static Analyzer
    SMT-Based Refutation of Spurious Bug Reports in the Clang Static Analyzer Mikhail R. Gadelha∗, Enrico Steffinlongo∗, Lucas C. Cordeiroy, Bernd Fischerz, and Denis A. Nicole∗ ∗University of Southampton, UK. yUniversity of Manchester, UK. zStellenbosch University, South Africa. Abstract—We describe and evaluate a bug refutation extension bit in a is one, and (a & 1) ˆ 1 inverts the last bit in a. for the Clang Static Analyzer (CSA) that addresses the limi- The analyzer, however, produces the following (spurious) bug tations of the existing built-in constraint solver. In particular, report when analyzing the program: we complement CSA’s existing heuristics that remove spurious bug reports. We encode the path constraints produced by CSA as Satisfiability Modulo Theories (SMT) problems, use SMT main.c:4:12: warning: Dereference of null solvers to precisely check them for satisfiability, and remove pointer (loaded from variable ’z’) bug reports whose associated path constraints are unsatisfi- return *z; able. Our refutation extension refutes spurious bug reports in ˆ˜ 8 out of 12 widely used open-source applications; on aver- age, it refutes ca. 7% of all bug reports, and never refutes 1 warning generated. any true bug report. It incurs only negligible performance overheads, and on average adds 1.2% to the runtime of the The null pointer dereference reported here means that CSA full Clang/LLVM toolchain. A demonstration is available at claims to nevertheless have found a path where the dereference https://www.youtube.com/watch?v=ylW5iRYNsGA. of z is reachable. Such spurious bug reports are in practice common; in our I.
    [Show full text]
  • Compiling and Makefiles
    Compiling C Programs Makefiles Compiling and Makefiles 2501ICT/7421ICTNathan René Hexel School of Information and Communication Technology Griffith University Semester 1, 2012 René Hexel Compiling and Makefiles Compiling C Programs Makefiles Outline 1 Compiling C Programs 2 Makefiles Using the make Utility Makefiles for Objective-C Code Makefiles for C++ Code René Hexel Compiling and Makefiles Compiling C Programs Makefiles Compiling C Programs Integrated Development Environment (IDE) Eclipse, XCode, Visual C++, Project Center, . Compiles programs at the press of a button (like BlueJ) Often difficult to customise Very rarely support multiple platforms and languages Command Line Requires manual invocation Requires knowledge of command line parameters Can be tedious for large projects Cross-platform and -language compilers (e.g. clang) Makefiles Combine the best of both worlds Recompile a complex project with a simple make command René Hexel Compiling and Makefiles Compiling C Programs Makefiles Getting a Command Line Interface Via Dwarf ssh dwarf.ict.griffith.edu.au using putty (Windows) Via a local Terminal Mac OS X: e.g. Applications / Utilities / Terminal.app Linux: e.g. through the Gnome program menu Windows: e.g. Start / Programs / Programming Tools / GNUstep / Shell ) Enter commands to compile your program Hit Return (or Enter) after every command! René Hexel Compiling and Makefiles Compiling C Programs Makefiles Compiling a C program using clang or gcc Once on the command line change to the directory (folder) your program is in cd /my/example/directory
    [Show full text]
  • ENCM 335 Fall 2018: Command-Line C Programming on Macos
    page 1 of 4 ENCM 335 Fall 2018: Command-line C programming on macOS Steve Norman Department of Electrical & Computer Engineering University of Calgary September 2018 Introduction This document is intended to help students who would like to do ENCM 335 C pro- gramming on an Apple Mac laptop or desktop computer. A note about software versions The information in this document was prepared using the latest versions of macOS Sierra version 10.12.6 and Xcode 9.2, the latest version of Xcode available for that version of macOS. Things should work for you if you have other but fairly recent versions of macOS and Xcode. If you have versions that are several years old, though you may experience difficulties that I'm not able to help with. Essential Software There are several key applications needed to do command-line C programming on a Mac. Web browser I assume you all know how to use a web browser to find course documents, so I won't say anything more about web browsers here. Finder Finder is the tool built in to macOS for browsing folders and files. It really helps if you're fluent with its features. Terminal You'll need Terminal to enter commands and look at output of commands. To start it up, look in Utilities, which is a folder within the Applications folder. It probably makes sense to drag the icon for Terminal to the macOS Dock, so that you can launch it quickly. macOS Terminal runs the same bash shell that runs in Cygwin Terminal, so commands like cd, ls, mkdir, and so on, are all available on your Mac.
    [Show full text]
  • Microkernel Construction Introduction
    Microkernel Construction Introduction Nils Asmussen 04/09/2020 1 / 32 Normal Organization Thursday, 4th DS, 2 SWS Slides: www.tudos.org ! Studies ! Lectures ! MKC Subscribe to our mailing list: www.tudos.org/mailman/listinfo/mkc2020 In winter term: Microkernel-based operating systems (MOS) Various labs 2 / 32 Organization due to COVID-19 Slides and video recordings of lectures will be published Questions can be asked on the mailing list Subscribe to the mailing list! Practical exercises are planed for the end of the semester Depending on how COVID-19 continues, exercises are in person or we use some video-conferencing tool 3 / 32 Goals 1 Provide deeper understanding of OS mechanisms 2 Look at the implementation details of microkernels 3 Make you become enthusiastic microkernel hackers 4 Propaganda for OS research done at TU Dresden and Barkhausen Institut 4 / 32 Outline Organization Monolithic vs. Microkernel Kernel design comparison Examples for microkernel-based systems Vision vs. Reality Challenges Overview About L4/NOVA 5 / 32 Monolithic Kernel System Design u s Application Application Application e r k Kernel e r File Network n e Systems Stacks l m Memory Process o Drivers Management Management d e Hardware 6 / 32 Monolithic Kernel OS (Propaganda) System components run in privileged mode No protection between system components Faulty driver can crash the whole system Malicious app could exploit bug in faulty driver More than 2=3 of today's OS code are drivers No need for good system design Direct access to data structures Undocumented
    [Show full text]
  • Can Microkernels Mitigate Microarchitectural Attacks?⋆
    Can Microkernels Mitigate Microarchitectural Attacks?? Gunnar Grimsdal1, Patrik Lundgren2, Christian Vestlund3, Felipe Boeira1, and Mikael Asplund1[0000−0003−1916−3398] 1 Department of Computer and Information Science, Link¨oping University, Sweden ffelipe.boeira,[email protected] 2 Westermo Network Technologies [email protected] 3 Sectra AB, Link¨oping,Sweden Abstract. Microarchitectural attacks such as Meltdown and Spectre have attracted much attention recently. In this paper we study how effec- tive these attacks are on the Genode microkernel framework using three different kernels, Okl4, Nova, and Linux. We try to answer the question whether the strict process separation provided by Genode combined with security-oriented kernels such as Okl4 and Nova can mitigate microar- chitectural attacks. We evaluate the attack effectiveness by measuring the throughput of data transfer that violates the security properties of the system. Our results show that the underlying side-channel attack Flush+Reload used in both Meltdown and Spectre, is effective on all in- vestigated platforms. We were also able to achieve high throughput using the Spectre attack, but we were not able to show any effective Meltdown attack on Okl4 or Nova. Keywords: Genode, Meltdown, Spectre, Flush+Reload, Okl4, Nova 1 Introduction It used to be the case that general-purpose operating systems were mostly found in desktop computers and servers. However, as IoT devices are becoming in- creasingly more sophisticated, they tend more and more to require a powerful operating system such as Linux, since otherwise all basic services must be im- plemented and maintained by the device developers. At the same time, security has become a prime concern both in IoT and in the cloud domain.
    [Show full text]
  • Operating System Support for Run-Time Security with a Trusted Execution Environment
    Operating System Support for Run-Time Security with a Trusted Execution Environment - Usage Control and Trusted Storage for Linux-based Systems - by Javier Gonz´alez Ph.D Thesis IT University of Copenhagen Advisor: Philippe Bonnet Submitted: January 31, 2015 Last Revision: May 30, 2015 ITU DS-nummer: D-2015-107 ISSN: 1602-3536 ISBN: 978-87-7949-302-5 1 Contents Preface8 1 Introduction 10 1.1 Context....................................... 10 1.2 Problem....................................... 12 1.3 Approach...................................... 14 1.4 Contribution.................................... 15 1.5 Thesis Structure.................................. 16 I State of the Art 18 2 Trusted Execution Environments 20 2.1 Smart Cards.................................... 21 2.1.1 Secure Element............................... 23 2.2 Trusted Platform Module (TPM)......................... 23 2.3 Intel Security Extensions.............................. 26 2.3.1 Intel TXT.................................. 26 2.3.2 Intel SGX.................................. 27 2.4 ARM TrustZone.................................. 29 2.5 Other Techniques.................................. 32 2.5.1 Hardware Replication........................... 32 2.5.2 Hardware Virtualization.......................... 33 2.5.3 Only Software............................... 33 2.6 Discussion...................................... 33 3 Run-Time Security 36 3.1 Access and Usage Control............................. 36 3.2 Data Protection................................... 39 3.3 Reference
    [Show full text]
  • Compiling Linux with LLVM
    Open Source Open Possibilities Compiling Linux with LLVM Presented by: Mark Charlebois Presentation Date: 06/07/2012 PAGE 1 Open Source Open Possibilities Agenda Why would I want to use Clang to compile Linux? Status updates: cross compiling for ARM with Clang building Linux kernel with Clang running Linux compiled with Clang To do list PAGE 2 Open Source Open Possibilities Open Source Open Possibilities Why Would I Want to Use Clang to Compile Linux? PAGE 3 Open Source Open Possibilities Better Diagnostics $ gcc-4.2 -fsyntax-only t.c t.c:7: error: invalid operands to binary + (have 'int' and 'struct A') $ clang -fsyntax-only t.c t.c:7:39: error: invalid operands to binary expression ('int' and 'struct A') return y + func(y ? ((SomeA.X + 40) + SomeA) / 42 + SomeA.X : SomeA.X); ~~~~~~~~~~~~~~ ^ ~~~~~ See http://clang.llvm.org/diagnostics.html for more examples GCC extensions: all extensions are explicitly recognized as such and marked with extension diagnostics, which can be mapped to warnings, errors, or just ignored. Google builds their products also with Clang just for the better debug output Rich diagnostic output enables auto-generation of patches PAGE 4 Open Source Open Possibilities Fix-it Hints "Fix-it" hints provide advice for fixing small, localized problems in source code. $ clang t.c t.c:5:28: warning: use of GNU old-style field designator extension struct point origin = { x: 0.0, y: 0.0 }; ~~ ^ .x = t.c:5:36: warning: use of GNU old-style field designator extension struct point origin = { x: 0.0, y: 0.0 }; ~~ ^ .y = PAGE 5
    [Show full text]
  • Code Transformation and Analysis Using Clang and LLVM Static and Dynamic Analysis
    Code transformation and analysis using Clang and LLVM Static and Dynamic Analysis Hal Finkel1 and G´abor Horv´ath2 Computer Science Summer School 2017 1 Argonne National Laboratory 2 Ericsson and E¨otv¨osLor´adUniversity Table of contents 1. Introduction 2. Static Analysis with Clang 3. Instrumentation and More 1 Introduction Space of Techniques During this set of lectures we'll cover a space of techniques for the analysis and transformation of code using LLVM. Each of these techniques have overlapping areas of applicability: Static Analysis LLVM Instrumentation Source Transformation 2 Space of Techniques When to use source-to-source transformation: • When you need to use the instrumented code with multiple compilers. • When you intend for the instrumentation to become a permanent part of the code base. You'll end up being concerned with the textual formatting of the instrumentation if humans also need to maintain or enhance this same code. 3 Space of Techniques When to use Clang's static analysis: • When the analysis can be performed on an AST representation. • When you'd like to maintain a strong connection to the original source code. • When false negatives are acceptable (i.e. it is okay if you miss problems). https://clang-analyzer.llvm.org/ 4 Space of Techniques When to use IR instrumentation: • When the necessary conditions can be (or can only be) detected at runtime (often in conjunction with a specialized runtime library). • When you require stronger coverage guarantees than static analysis. • When you'd like to reduce the cost of the instrumentation by running optimizations before the instrumentation is inserted, after the instrumentation is inserted, or both.
    [Show full text]
  • View Article(3467)
    Problems of information technology, 2018, №1, 92–97 Kamran E. Jafarzade DOI: 10.25045/jpit.v09.i1.10 Institute of Information Technology of ANAS, Baku, Azerbaijan [email protected] COMPARATIVE ANALYSIS OF THE SOFTWARE USED IN SUPERCOMPUTER TECHNOLOGIES The article considers the classification of the types of supercomputer architectures, such as MPP, SMP and cluster, including software and application programming interfaces: MPI and PVM. It also offers a comparative analysis of software in the study of the dynamics of the distribution of operating systems (OS) for the last year of use in supercomputer technologies. In addition, the effectiveness of the use of CentOS software on the scientific network "AzScienceNet" is analyzed. Keywords: supercomputer, operating system, software, cluster, SMP-architecture, MPP-architecture, MPI, PVM, CentOS. Introduction Supercomputer is a computer with high computing performance compared to a regular computer. Supercomputers are often used for scientific and engineering applications that need to process very large databases or perform a large number of calculations. The performance of a supercomputer is measured in floating-point operations per second (FLOPS) instead of millions of instructions per second (MIPS). Since 2015, the supercomputers performing up to quadrillion FLOPS have started to be developed. Modern supercomputers represent a large number of high performance server computers, which are interconnected via a local high-speed backbone to achieve the highest performance [1]. Supercomputers were originally introduced in the 1960s and bearing the name or monogram of the companies such as Seymour Cray of Control Data Corporation (CDC), Cray Research over the next decades. By the end of the 20th century, massively parallel supercomputers with tens of thousands of available processors started to be manufactured.
    [Show full text]
  • KOS - Principles, Design, and Implementation
    KOS - Principles, Design, and Implementation Martin Karsten, University of Waterloo Work In Progress - September 29, 2015 Abstract KOS is an experimental operating system kernel that is designed to be simple and accessible to serve as a platform for research, experimen- tation, and teaching. The overall focus of this project is on system-level infrastructure software, in particular runtime systems. 1 Introduction KOS (pronounce "Chaos") is an experimental operating system kernel that is designed to be simple and accessible to serve as a platform for research, ex- perimentation, and teaching. It is focused on building a nucleus kernel that provides the basic set of operating system functionality, primarily for resource mediation, that must realistically be implemented for execution in privileged mode. While being simple KOS is not simplistic and avoids taking design shortcuts that would prohibit adding more sophisticated resource management strategies later on { inside the kernel or at higher software layers. The nu- cleus kernel is augmented with several prototype subsystems typically found in an operating system to eventually support running realistic applications. The entire code base is written in C++, except for small assembler parts. The C++ code makes use of advanced language features, such as code reuse with efficient strong type safety using templates, the C++ library for data struc- ture reuse, as well as (limited) polymorphism. Existing open-source software is reused for non-nucleus subsystems as much as possible. The project is hosted at https://git.uwaterloo.ca/mkarsten/KOS 2 Motivation In principle, an operating system has two basic functions. First, it consolidates low-level hardware interfaces and provides higher-level software abstractions to facilitate and alleviate application programming.
    [Show full text]