WAMOS 2015 Second Wiesbaden Workshop on Advanced Microkernel Operating Systems
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A Microkernel API for Fine-Grained Decomposition
A Microkernel API for Fine-Grained Decomposition Sebastian Reichelt Jan Stoess Frank Bellosa System Architecture Group, University of Karlsruhe, Germany freichelt,stoess,[email protected] ABSTRACT from the microkernel APIs in existence. The need, for in- Microkernel-based operating systems typically require spe- stance, to explicitly pass messages between servers, or the cial attention to issues that otherwise arise only in dis- need to set up threads and address spaces in every server for tributed systems. The resulting extra code degrades per- parallelism or protection require OS developers to adopt the formance and increases development effort, severely limiting mindset of a distributed-system programmer rather than to decomposition granularity. take advantage of their knowledge on traditional OS design. We present a new microkernel design that enables OS devel- Distributed-system paradigms, though well-understood and opers to decompose systems into very fine-grained servers. suited for physically (and, thus, coarsely) partitioned sys- We avoid the typical obstacles by defining servers as light- tems, present obstacles to the fine-grained decomposition weight, passive objects. We replace complex IPC mecha- required to exploit the benefits of microkernels: First, a nisms by a simple function-call approach, and our passive, lot of development effort must be spent into matching the module-like server model obviates the need to create threads OS structure to the architecture of the selected microkernel, in every server. Server code is compiled into small self- which also hinders porting existing code from monolithic sys- contained files, which can be loaded into the same address tems. Second, the more servers exist | a desired property space (for speed) or different address spaces (for safety). -
A Case Against the GOT' O William a . Wulf, Carnegie-Mellon Universit Y
A Case Against the GOT' O William A . Wulf, Carnegie-Mellon Universit y ABSTRAC T suggestion to ban the goto appears to have been a part of the computing folklore for several years , It has been proposed, by E . W . Dijkstra and others , to this author's knowledge the suggestion wa s that the goto statement in programming language i s first made in print by Professor E . W . Dijkstra i n a principal culprit in programs which are diffi- a letter to the editor of the _Communications o f cult to understand, modify, and debug . More cor- the ACM in 1968 (1) . rectly, the argument is that it is possible t o In this paper we shall examine the rational e use the goto to synthesize program structures wit h for the elimination of the Soto in programin g these undesirable properties . Not all uses of th e languages, and some of the theoretical and practi- goto are to be considered harmful ; however, it i s cal implications of its (total) elimination . further argued that the "good" uses of the got o fall into one of a small number of specific case s RATIONAL E which may be handled by specific language con- structs . This paper summarizes the arguments i n At one level, the rationale for eliminatin g favor of eliminating the goto statement and som e the poto has already been given in the introduc- of the theoretical and practical implications o f tion . Namely, it is possible to use the goto in a the proposal . manner which obscures the logical structure of a program to a point where it becomes virtually im- KEY WORDS AND PHRASES : programming, programmin g possible to understand (1,3,4), It is not claimed languages, goto-less programming, structured pro- that every use of the goto obscures the logica l grammin g structure of a program ; it is only claimed that i t CR CATEGORIES : 4 .2, 4 .22, 5 .2 4 is possible to use the Soto to fabricate a "rat' s nest" of control flow which has the undesirabl e INTRODUCTION properties mentioned above . -
Does the Seventh Amendment Compel Fact-‐Finding Before
HAVE WE GONE TOO FAR: DOES THE SEVENTH AMENDMENT COMPEL FACT-FINDING BEFORE REACHING A DECISION ON PATENT- ELIGIBLE SUBJECT MATTER? JESSE D.H. SNYDER* I. INTRODUCTION Something seems amiss. Settled notions of what can be Patenta- ble are changing.1 To complicate matters further, so far, neither the SuPreme Court nor the Federal Circuit has addressed whether the in- quiry into Patent-eliGible subject matter is factual, legal, or both. And while the scoPe of Patentable subject matter is understandably con- strictinG, the end result may not be coterminous with the SuPreme Court’s Guidance in Alice Corporation Party Limited v. CLS Bank.2 Under Alice, which built uPon the Patent-eliGible subject matter frameworks of Prior cases, for those Patent claims that are directed to a Patent- ineligible concePt (e.G., abstract ideas), Patentability turns on whether an “inventive concePt” exists to “‘transform the nature of the claim’ into a Patent-eliGible aPPlication.”3 The lower courts have seized on the Alice holding, inhuming Pa- tents whose subject-matter failures render them invalid as a matter of law. But what if the means adoPted by the lower courts to reach that leGal conclusion also sidestePs certain constitutional guarantees? What if they are simPlifyinG the analysis at a facial level when a more granular investigation is required? What if, at the motion to dismiss staGe, fact-findinG is still required to determine whether a Patent is * 2015-2016 term law clerk to the Honorable Jimmie V. Reyna of the U.S. Court of APPeals for the Federal Circuit. I earned my J.D., summa cum laude, from Texas Wesleyan School of Law and my B.S. -
Extensible Distributed Operating System for Reliable Control Systems
194 Extensible Distributed Operating System for Reliable Control Systems Katsumi Maruyama, Kazuya Kodama, Soichiro Hidaka, Hiromichi Hashizume National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo, Japan Email:{maruyama,kazuya,hidaka,has}@nii.ac.jp Abstract small monitor-like OSs are used. However, these monitor- like OSs lack program protection mechanisms, and program Since most control systems software is hardware-related, development is difficult. real-time-oriented and complex, adaptable OSs which help Therefore, an extensible/adaptable OS for control sys- program productivity and maintainability improvement are tems is required . We are developing a new OS character- in strong demand. ized by: We are developing an adaptable and extensible OS based on micro-kernel and multi-server scheme: each server runs • Use of an efficient and flexible micro-kernel (L4-ka). • Multi-server based modular OS. (Each OS service is in a protected mode interacting only via messages, and implemented as individual user-level process.) could be added/extended/deleted easily. Since this OS is • Robustness. Only the micro-kernel runs in kernel highly modularized, inter-process messaging overhead is a mode and in kernel space. Other modules run in a pro- concern. Our implementation proved good efficiency and tected user space and mode. maintainability. • Hardware driver programs in user-level process. • Flexible distributed processing by global message passing. 1. Introduction This OS structure proved to enhance OS modularity and ease of programming. However, inter-process messaging Most systems, from large scale public telephone switch- overhead should be considered . We measured the overhead, ing systems to home electronics, are controlled by software, and the overhead was proved to be small enough. -
Run-Time Reconfigurable RTOS for Reconfigurable Systems-On-Chip
Run-time Reconfigurable RTOS for Reconfigurable Systems-on-Chip Dissertation A thesis submited to the Faculty of Computer Science, Electrical Engineering and Mathematics of the University of Paderborn and to the Graduate Program in Electrical Engineering (PPGEE) of the Federal University of Rio Grande do Sul in partial fulfillment of the requirements for the degree of Dr. rer. nat. and Dr. in Electrical Engineering Marcelo G¨otz November, 2007 Supervisors: Prof. Dr. rer. nat. Franz J. Rammig, University of Paderborn, Germany Prof. Dr.-Ing. Carlos E. Pereira, Federal University of Rio Grande do Sul, Brazil Public examination in Paderborn, Germany Additional members of examination committee: Prof. Dr. Marco Platzner Prof. Dr. Urlich R¨uckert Dr. Mario Porrmann Date: April 23, 2007 Public examination in Porto Alegre, Brazil Additional members of examination committee: Prof. Dr. Fl´avioRech Wagner Prof. Dr. Luigi Carro Prof. Dr. Altamiro Amadeu Susin Prof. Dr. Leandro Buss Becker Prof. Dr. Fernando Gehm Moraes Date: October 11, 2007 Acknowledgements This PhD thesis was carried out, in his great majority, at the Department of Computer Science, Electrical Engineering and Mathematics of the University of Paderborn, during my time as a fellow of the working group of Prof. Dr. Franz J. Rammig. Due to a formal agreement between Federal University of Rio Grande do Sul (UFRGS) and University of Paderborn, I had the opportunity to receive a bi-national doctoral degree. Therefore, I had to accomplished, in addition, the PhD Graduate Program in Electrical Engineering of UFRGS. So, I hereby acknowledge, without mention everyone personally, all persons involved in making this agreement possible. -
All Computer Applications Need to Store and Retrieve Information
MyFS: An Enhanced File System for MINIX A Dissertation Submitted in partial fulfillment of the requirement for the award of the degree of MASTER OF ENGINEERING ( COMPUTER TECHNOLOGY & APPLICATIONS ) By ASHISH BHAWSAR College Roll No. 05/CTA/03 Delhi University Roll No. 3005 Under the guidance of Prof. Asok De Department Of Computer Engineering Delhi College Of Engineering, New Delhi-110042 (University of Delhi) July-2005 1 CERTIFICATE This is to certify that the dissertation entitled “MyFS: An Enhanced File System for MINIX” submitted by Ashish Bhawsar in the partial fulfillment of the requirement for the award of degree of Master of Engineering in Computer Technology and Application, Delhi College of Engineering is an account of his work carried out under my guidance and supervision. Professor D. Roy Choudhury Professor Asok De Head of Department Head of Department Department of Computer Engineering Department of Information Technology Delhi College of Engineering Delhi College of Engineering Delhi Delhi 2 ACKNOWLEDGEMENT It is a great pleasure to have the opportunity to extent my heartiest felt gratitude to everybody who helped me throughout the course of this project. I would like to express my heartiest felt regards to Dr. Asok De, Head of the Department, Department of Information Technology for the constant motivation and support during the duration of this project. It is my privilege and owner to have worked under the supervision. His invaluable guidance and helpful discussions in every stage of this thesis really helped me in materializing this project. It is indeed difficult to put his contribution in few words. I would also like to take this opportunity to present my most sincere regards to Dr. -
Introduction
1 INTRODUCTION A modern computer consists of one or more processors, some main memory, disks, printers, a keyboard, a mouse, a display, network interfaces, and various other input/output devices. All in all, a complex system.oo If every application pro- grammer had to understand how all these things work in detail, no code would ever get written. Furthermore, managing all these components and using them optimally is an exceedingly challenging job. For this reason, computers are equipped with a layer of software called the operating system, whose job is to provide user pro- grams with a better, simpler, cleaner, model of the computer and to handle manag- ing all the resources just mentioned. Operating systems are the subject of this book. Most readers will have had some experience with an operating system such as Windows, Linux, FreeBSD, or OS X, but appearances can be deceiving. The pro- gram that users interact with, usually called the shell when it is text based and the GUI (Graphical User Interface)—which is pronounced ‘‘gooey’’—when it uses icons, is actually not part of the operating system, although it uses the operating system to get its work done. A simple overview of the main components under discussion here is given in Fig. 1-1. Here we see the hardware at the bottom. The hardware consists of chips, boards, disks, a keyboard, a monitor, and similar physical objects. On top of the hardware is the software. Most computers have two modes of operation: kernel mode and user mode. The operating system, the most fundamental piece of soft- ware, runs in kernel mode (also called supervisor mode). -
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 -
Shri Vaishnav Vidyapeeth Vishwavidyalaya, Indore
SHRI VAISHNAV VIDYAPEETH VISHWAVIDYALAYA, INDORE Memories are special moments that tell our story SMRITI मृत ALUMNI DIRECTORY 2020 The rising flame epitomises leadership through enlightenment The bright orange colour represents brilliance and colour blue reflects serenity and infinity तमसो मा योतगमय Lead me from darkness to light ABOUT UNIVERSITY Shri Vaishnav Vidyapeeth Vishwavidyalaya is a state private university established under Madhya Pradesh Niji Vishwavidyalaya (Sthapana Avam Sanchalan) Adhiniyam in 2015 at Indore, MP(India). The University has been established with a vision to be a leader in shaping better future for mankind through quality education, training and research. It shall pursue the mission to make a difference in sustaining the growth of global societies by developing socially responsible citizens. Value based education being at the helm, the University offers degree and diploma programs through 13 constituent institutes and schools, besides Faculty of Doctoral Studies and Research. Some of the objectives of the University are as under: • To provide teaching and training in higher education and make provision for research as well as advancement and dissemination of knowledge. • To ensure world class quality in its offerings and create higher levels of intellectual abilities. • To create centres of excellence for research and development for sharing knowledge and its applications. Shri Vaishnav Vidyapeeth Vishwavidyalaya at Indore is a multi-disciplinary university focusing on the needs of various segments of the society. FROM THE DESK OF CHANCELLOR “To emerge as a winner, learn to balance relaxation and action” Shri Vaishnav Vidyapeeth Vishwavidyalaya was conceived as an institution of higher learning for imparting quality education to the young and experienced learners alike. -
Microkernel Construction Introduction
Microkernel Construction Introduction Nils Asmussen 04/06/2017 1 / 28 Outline Introduction Goals Administration Monolithic vs. Microkernel Overview About L4/NOVA 2 / 28 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 at TU Dresden 3 / 28 Administration Thursday, 4th DS, 2 SWS Slides: www.tudos.org ! Teaching ! Microkernel Construction Subscribe to our mailing list: www.tudos.org/mailman/listinfo/mkc2017 In winter term: Microkernel-based operating systems (MOS) Various labs 4 / 28 Outline Introduction Monolithic vs. Microkernel Kernel design comparison Examples for microkernel-based systems Vision vs. Reality Challenges Overview About L4/NOVA 5 / 28 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 / 28 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 and frequently changing interfaces Big and inflexible Difficult to replace system components Difficult to understand and maintain Why something different? ! Increasingly difficult to manage growing OS complexity 7 / 28 Microkernel System Design Application -
Assessing Unikernel Security April 2, 2019 – Version 1.0
NCC Group Whitepaper Assessing Unikernel Security April 2, 2019 – Version 1.0 Prepared by Spencer Michaels Jeff Dileo Abstract Unikernels are small, specialized, single-address-space machine images constructed by treating component applications and drivers like libraries and compiling them, along with a kernel and a thin OS layer, into a single binary blob. Proponents of unikernels claim that their smaller codebase and lack of excess services make them more efficient and secure than full-OS virtual machines and containers. We surveyed two major unikernels, Rumprun and IncludeOS, and found that this was decidedly not the case: unikernels, which in many ways resemble embedded systems, appear to have a similarly minimal level of security. Features like ASLR, W^X, stack canaries, heap integrity checks and more are either completely absent or seriously flawed. If an application running on such a system contains a memory corruption vulnerability, it is often possible for attackers to gain code execution, even in cases where the applica- tion’s source and binary are unknown. Furthermore, because the application and the kernel run together as a single process, an attacker who compromises a unikernel can immediately exploit functionality that would require privilege escalation on a regular OS, e.g. arbitrary packet I/O. We demonstrate such attacks on both Rumprun and IncludeOS unikernels, and recommend measures to mitigate them. Table of Contents 1 Introduction to Unikernels . 4 2 Threat Model Considerations . 5 2.1 Unikernel Capabilities ................................................................ 5 2.2 Unikernels Versus Containers .......................................................... 5 3 Hypothesis . 6 4 Testing Methodology . 7 4.1 ASLR ................................................................................ 7 4.2 Page Protections .................................................................... -
L4 – Virtualization and Beyond
L4 – Virtualization and Beyond Hermann Härtig!," Michael Roitzsch! Adam Lackorzynski" Björn Döbel" Alexander Böttcher! #!Department of Computer Science# "GWT-TUD GmbH # Technische Universität Dresden# 01187 Dresden, Germany # 01062 Dresden, Germany {haertig,mroi,adam,doebel,boettcher}@os.inf.tu-dresden.de Abstract Mac OS X environment, using full hardware After being introduced by IBM in the 1960s, acceleration by the GPU. Virtual machines are virtualization has experienced a renaissance in used to test potentially malicious software recent years. It has become a major industry trend without risking the host environment and they in the server context and is also popular on help developers in debugging crashes with back- consumer desktops. In addition to the well-known in-time execution. benefits of server consolidation and legacy In the server world, virtual machines are used to preservation, virtualization is now considered in consolidate multiple services previously located embedded systems. In this paper, we want to look on dedicated machines. Running them within beyond the term to evaluate advantages and virtual machines on one physical server eases downsides of various virtualization approaches. management and helps saving power by We show how virtualization can be increasing utilization. In server farms, migration complemented or even superseded by modern of virtual machines between servers is used to operating system paradigms. Using L4 as the balance load with the potential of shutting down basis for virtualization and as an advanced completely unloaded servers or adding more to microkernel provides a best-of-both-worlds increase capacity. Lastly, virtual machines also combination. Microkernels can contribute proven isolate different customers who can purchase real-time capabilities and small trusted computing virtual shares of a physical server in a data center.