Kernel Concepts Presented by Hayden Tremethick
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Interrupts and Exceptions CPU Modes and Address Spaces Dual-Mode Of
CPU Modes and Address Spaces There are two processor (CPU) modes of operation: • Kernel (Supervisor) Mode and • User Mode The processor is in Kernel Mode when CPU mode bit in Status Interrupts and Exceptions register is set to zero. The processor enters Kernel Mode at power-up, or as result of an interrupt, exception, or error. The processor leaves Kernel Mode and enters User Mode when the CPU mode bit is set to one (by some instruction). Memory address space is divided in two ranges (simplified): • User address space – addresses in the range [0 – 7FFFFFFF16] Studying Assignment: A.7 • Kernel address space Reading Assignment: 3.1-3.2, A.10 – addresses in the range [8000000016 – FFFFFFFF16] g. babic Presentation B 28 g. babic 29 Dual-Mode of CPU Operation MIPS Privilege Instructions • CPU mode bit indicates the current CPU mode: 0 (=kernel) With CPU in User Mode, the program in execution has access or 1 (=user). only to the CPU and FPU registers, while when CPU operates • When an interrupt occurs, CPU hardware switches to the in Kernel Mode, the program has access to the full capabilities kernel mode. of processor including CP0 registers. • Switching to user mode (from kernel mode) done by setting CPU mode bit (by an instruction). Privileged instructions can not be executed when the Exception/Interrupt processor is in User mode, they can be executed only when the processor is in Kernel mode. kernel user Examples of MIPS privileged instructions: Set user mode • any instruction that accesses Kernel address space • all instructions that access any of CP0 registers, e.g. -
RTA-OSEK Binding Manual: TMS470/TI
RTA-OSEK Binding Manual: TMS470/TI Contact Details ETAS Group www.etasgroup.com Germany USA ETAS GmbH ETAS Inc. Borsigstraße 14 3021 Miller Road 70469 Stuttgart Ann Arbor, MI 48103 Tel.:+49 (711) 8 96 61-102 Tel.: +1 (888) ETAS INC Fax:+49 (711) 8 96 61-106 Fax: +1 (734) 997-94 49 www.etas.de www.etasinc.com Japan France ETAS K.K. ETAS S.A.S. Queen's Tower C-17F, 1, place des États-Unis 2-3-5, Minatomirai, Nishi-ku, SILIC 307 Yokohama, Kanagawa 94588 Rungis Cedex 220-6217 Japan Tel.: +33 (1) 56 70 00 50 Tel.: +81 (45) 222-0900 Fax: +33 (1) 56 70 00 51 Fax: +81 (45) 222-0956 www.etas.fr www.etas.co.jp Korea Great Britain ETAS Korea Co. Ltd. ETAS UK Ltd. 4F, 705 Bldg. 70-5 Studio 3, Waterside Court Yangjae-dong, Seocho-gu Third Avenue, Centrum 100 Seoul 137-889, Korea Burton-upon-Trent Tel.: +82 (2) 57 47-016 Staffordshire DE14 2WQ Fax: +82 (2) 57 47-120 Tel.: +44 (0) 1283 - 54 65 12 www.etas.co.kr Fax: +44 (0) 1283 - 54 87 67 www.etas-uk.net Copyright Notice © 2001 - 2007 LiveDevices Ltd. All rights reserved. Version: M00088-001 No part of this document may be reproduced without the prior written consent of LiveDevices Ltd. The software described in this document is furnished under a license and may only be used or copied in accordance with the terms of such a license. Disclaimer The information in this document is subject to change without notice and does not represent a commitment on any part of LiveDevices. -
Bringing Virtualization to the X86 Architecture with the Original Vmware Workstation
12 Bringing Virtualization to the x86 Architecture with the Original VMware Workstation EDOUARD BUGNION, Stanford University SCOTT DEVINE, VMware Inc. MENDEL ROSENBLUM, Stanford University JEREMY SUGERMAN, Talaria Technologies, Inc. EDWARD Y. WANG, Cumulus Networks, Inc. This article describes the historical context, technical challenges, and main implementation techniques used by VMware Workstation to bring virtualization to the x86 architecture in 1999. Although virtual machine monitors (VMMs) had been around for decades, they were traditionally designed as part of monolithic, single-vendor architectures with explicit support for virtualization. In contrast, the x86 architecture lacked virtualization support, and the industry around it had disaggregated into an ecosystem, with different ven- dors controlling the computers, CPUs, peripherals, operating systems, and applications, none of them asking for virtualization. We chose to build our solution independently of these vendors. As a result, VMware Workstation had to deal with new challenges associated with (i) the lack of virtual- ization support in the x86 architecture, (ii) the daunting complexity of the architecture itself, (iii) the need to support a broad combination of peripherals, and (iv) the need to offer a simple user experience within existing environments. These new challenges led us to a novel combination of well-known virtualization techniques, techniques from other domains, and new techniques. VMware Workstation combined a hosted architecture with a VMM. The hosted architecture enabled a simple user experience and offered broad hardware compatibility. Rather than exposing I/O diversity to the virtual machines, VMware Workstation also relied on software emulation of I/O devices. The VMM combined a trap-and-emulate direct execution engine with a system-level dynamic binary translator to ef- ficiently virtualize the x86 architecture and support most commodity operating systems. -
Distribution and Operating Systems
Distributed Systems | Distribution and Operating Systems Allan Clark School of Informatics University of Edinburgh http://www.inf.ed.ac.uk/teaching/courses/ds Autumn Term 2012 Distribution and Operating Systems Overview I This part of the course will be chiefly concerned with the components of a modern operating system which allow for distributed systems I We will examine the design of an operating system within the context that we expect it to be used as part of a network of communicating peers, even if only as a client I In particular we will look at providing concurrency of individual processes all running on the same machine I Concurrency is important because messages take time to send and the machine can do useful work in between messages which may arrive at any time I An important point is that in general we hope to provide transparency of concurrency, that is each process believes that it has sole use of the machine I Recent client machines such as smartphones, have, to some extent, shunned this idea Distribution and Operating Systems Operating Systems I An Operating System is a single process which has direct access to the hardware of the machine upon which it is run I The operating system must therefore provide and manage access to: I The processor I System memory I Storage media I Networks I Other devices, printers, scanners, coffee machines etc http://fotis.home.cern.ch/fotis/Coffee.html Distribution and Operating Systems Operating Systems I As a provider of access to physical resources we are interested in the operating system providing: I Encapsulation: Not only should the operating system provide access to physical resources but also hide their low-level details behind a useful abstraction that applications can use to get work done I Concurrent Processing: Applications may access these physcial resources (including the processor) concurrently, and the process manager is responsible for achieving concurrency transparency I Protection: Physical resources should only be accessed by processes with the correct permissions and then only in safe ways. -
Impact of Hybrid Kernel for the Performance of the Operating System
ISSN (Online) 2278-1021 ISSN (Print) 2319-5940 International Journal of Advanced Research in Computer and Communication Engineering Vol. 4, Issue 3, March 2015 Impact of Hybrid Kernel for the Performance of the Operating System Miss Hema K Reddy1, Dr. M A Pund2 ME Student, CSE , Prof. Ram Meghe Institute of Technology Research, Badnera1 Professor, CSE, Prof. Ram Meghe Institute of Technology & Research, Badnera2 Abstract: Embedded system application is a hot topic in today’s date & Linux gradually becomes the most important operating system for embedded applications. Embedded real-time system must be able to response and deal with system events within the pre-defined time limitation. In real-time multi-tasking system, a lot of events and multiple concurrent tasks are running at the same time. Therefore, to meet the system response time requirement, we must ensure that each mission can be achieved within the required time frame. Current Operating Systems includes a graphical user interface that is widely used. Due to the absence of Real-Time ability, current Operating Systems has not been suitable for all industrial applications. On the other hand normal operating system has the advantage of having both widespread applications and broad user acceptance. Moreover lot many low priced user programs are available. This is an attempt to create a way to make operating system useful for industrial real-time applications eliminating its disadvantages without giving up its advantages of popular user applications. Keywords: Operating System Kernel, Hybrid Kernel, Performance arguments. I. INTRODUCTION The Hybrid Kernel combines the Desktop OS and RTOS operating system provides a powerful tool for real-time so that they can run concurrently on the same PC and the systems design and development because of its real-time user can get best of both worlds. -
Introduction to Linux Operating System Table of Contents
Introduction to Linux Operating System Table of contents • Operating system tasks • UNIX history, Linux history • Linux basic features • Linux distributions • Building OS kernels • Linux modules • eBPF • Linux structure and kernel functions • Basic concepts – process, user mode and kernel mode, context switch, system calls, user stack and kernel stack, process state transitions • Kernel reports – what is going on in the kernel • Additional reading 2 Operating system tasks Operating System is a program that mediates between user and computer hardware. • Hides hardware details of the computer system by creating abstractions (virtual machines). Examples: – a unified way to access external devices, – sets of disk blocks seen as files with symbolic names, – large, fast, dedicated operating memory, – concurrent program execution (as an abstraction of parallelism), – a container provides OS-level virtualization by abstracting the „user space”. • Manages resources: – resources are objects necessary to execute the program, e.g. memory, processor (CPU), input/output, communication ports, – strategies for allocation and deallocation of resources (memory management, processor management, file management, device management), – efficiency of resource management determines efficient operation of computer hardware. • Provides a friendly interface. 3 Computer system layers (source: Stallings, Operating Systems) 4 UNIX history • Created in 1969; authors: Ken Thompson, Denis Ritchie from Bell Laboratories, machine: PDP-7, which had many features of MULTICS. -
AMD APP SDK V2.9.1
AMD APP SDK v2.9.1 FAQ 1 General Questions 1. Do I need to use additional software with the SDK? To run an OpenCL™ application, you must have an OpenCL™ runtime on your system. If your system includes a recent AMD discrete GPU, or an APU, you also should install the latest Catalyst™ drivers, which can be downloaded from AMD.com. Information on supported devices can be found at developer.amd.com/appsdk. If your system does not include a recent AMD discrete GPU, or APU, the SDK installs a CPU-only OpenCL™ run-time. Also, we recommend using the debugging profiling and analysis tools contained in the AMD CodeXL heterogeneous compute tools suite. 2. Which versions of the OpenCL™ standard does this SDK support? AMD APP SDK 2.9.1 supports the development of applications using the OpenCL™ Specification v 1.2. 3. Will applications developed to execute on OpenCL™ 1.1 still operate in an OpenCL™ 1.2 environment? OpenCL™ is designed to be backwards compatible. The OpenCL™ 1.2 run-time delivered with the AMD Catalyst drivers run any OpenCL™ 1.1-compliant application. However, an OpenCL™ 1.2-compliant application will not execute on an OpenCL™ 1.1 run-time if APIs only supported by OpenCL™ 1.2 are used. 4. Does AMD provide any additional OpenCL™ samples, other than those contained within the SDK? The most recent versions of all of the samples contained within the SDK are also available for individual download from the developer.amd.com/appsdk “Samples & Demos” page. This page also contains additional samples that either were too large to include in the SDK, or which have been developed since the most recent SDK release. -
Openafs Client for Macos
OpenAFS client for macOS Marcio Barbosa 2021 OpenAFS Workshop AGENDA • A high-level view of XNU • Kernel Extensions • Securing Modular Architecture • System Extensions • Apple Silicon • Conclusion • References / Contact A HIGH-LEVEL VIEW OF XNU A HIGH-LEVEL VIEW OF XNU • The Mac OS X kernel is called XNU. • Stands for X is Not UNIX. • Microkernel architecture? No, XNU is a hybrid kernel. FreeBSD Mach MONOLITHIC KERNELS • "Classic" kernel architecture. • Predominant in the UNIX and Linux realms. • All kernel functionality in one address space. • If any service fails, the whole system crashes. • Hard to extend. MICROKERNELS • Consists of only the core kernel functionality. • The rest of the functionality exported to external servers. • There exists complete isolation between the individual servers. • Communication between them is carried out by message passing. • Failure is contained. • Monolithic kernel failures usually trigger a complete kernel panic. • Performance can be an issue. HYBRID KERNELS • Hybrid kernels attempt to synthesize the best of both worlds. • The innermost core of the kernel is self-contained. • All other services are outside this core, but in the same memory space. • XNU is a hybrid. • The kernel is modular and allows for pluggable Kernel Extensions. • Absence of isolation exposes the system to bugs introduced by KEXTs. MONOLITHIC, MICROKERNELS, AND HYBRID Golftheman, Public domain, via Wikimedia Commons https://commons.wikimedia.org/wiki/File:OS-structure2.svg KERNEL EXTENSIONS KERNEL EXTENSIONS • No kernel can completely accommodate all the hardware, peripheral devices, and services available. • KEXTs are kernel modules, which may be dynamically inserted or removed on demand. • Augments kernel functionality with entirely self-contained subsystems. -
Operating Systems
Operating Systems − they will be added as we go • you can also use slides from previous years Petr Ročkai − they are already in study materials − but: not everything is covered in those These are draft (work in progress) lecture notes for PB152. It is expected to be gradually ��illed in, hopefully before the semester You are reading the lecture notes for the course PB152 Operating ends. For now, it is mostly a printable version of the slides. Systems. This is a supplementary resource based on the lecture Organisation slides, but with additional details that would not it into the slide format. These lecture notes should be self-contained in the sense • lectures, with an optional seminar that they only rely on knowledge you have from other courses, • written exam at the end like PB150 Computer Systems (or PB151) or PB071 Principles of − multiple choice Low-Level programming. Likewise, being familiar with the topics − free-form questions covered in these lecture notes is suficient to pass the exam. • 1 online test mid-term, 1 before exam − mainly training for the exam proper Books The written exam will consist of two parts, a multiple-choice test • there are a few good OS books (with exactly one correct answer on each question) and a free- • you are encouraged to get and read them form question. Additionally, you will be required to pass a mid- term test with the same pool of multiple-choice questions. The • A. Tanenbaum: Modern Operating Systems question pool is known in advance: both the entire mid-term and • A. -
Kguard: Lightweight Kernel Protection Against Return-To-User Attacks
kGuard: Lightweight Kernel Protection against Return-to-user Attacks VasileiosP.Kemerlis GeorgiosPortokalidis AngelosD.Keromytis Network Security Lab Department of Computer Science Columbia University, New York, NY, USA {vpk, porto, angelos}@cs.columbia.edu Abstract Such return-to-user (ret2usr) attacks have affected all major OSs, including Windows [60], Linux [16, 18], Return-to-user (ret2usr) attacks exploit the operating sys- and FreeBSD [19, 59, 61], while they are not limited to tem kernel, enabling local users to hijack privileged ex- x86 systems [23], but have also targeted the ARM [30], ecution paths and execute arbitrary code with elevated DEC [31], and PowerPC [25] architectures. privileges. Current defenses have proven to be inade- There are numerous reasons to why attacks against the quate, as they have been repeatedly circumvented, in- kernel are becoming more common. First and foremost, cur considerable overhead, or rely on extended hypervi- processes running with administrative privileges have be- sors and special hardware features. We present kGuard, come harder to exploit due to the various defense mech- a compiler plugin that augments the kernel with com- anisms adopted by modern OSs [34,52]. Second, NULL pact inline guards, which prevent ret2usr with low per- pointer dereference errors had not received significant at- formance and space overhead. kGuard can be used with tention, until recently, exactly because they were thought any operating system that features a weak separation be- impractical and too difficult to exploit. In fact, 2009 has tween kernel and user space, requires no modifications been proclaimed, by some security researchers, as “the to the OS, and is applicable to both 32- and 64-bit ar- year of the kernel NULL pointer dereference flaw”[15]. -
Vsphere Virtual Machine Administration
vSphere Virtual Machine Administration 02 APR 2020 VMware vSphere 7.0 VMware ESXi 7.0 vCenter Server 7.0 vSphere Virtual Machine Administration You can find the most up-to-date technical documentation on the VMware website at: https://docs.vmware.com/ VMware, Inc. 3401 Hillview Ave. Palo Alto, CA 94304 www.vmware.com © Copyright 2009-2020 VMware, Inc. All rights reserved. Copyright and trademark information. VMware, Inc. 2 Contents About vSphere Virtual Machine Administration 10 1 Updated Information 11 2 Introduction to VMware vSphere Virtual Machines 12 Virtual Machine Files 12 Virtual Machines and the Virtual Infrastructure 13 Virtual Machine Lifecycle 14 Virtual Machine Components 14 Virtual Machine Hardware Available to vSphere Virtual Machines 16 Virtual Machine Options 18 The vSphere Client 19 Where to Go From Here 20 3 Deploying Virtual Machines 21 Create a Virtual Machine with the New Virtual Machine Wizard 22 Clone a Virtual Machine to a Template 25 Deploy a Virtual Machine from a Template 28 Clone an Existing Virtual Machine 32 Cloning a Virtual Machine with Instant Clone 37 Clone a Template to a Template 37 Convert a Template to a Virtual Machine 40 4 Deploying OVF and OVA Templates 42 OVF and OVA File Formats and Templates 42 Deploy an OVF or OVA Template 43 Export an OVF Template 45 Browse VMware Virtual Appliance Marketplace 46 5 Using Content Libraries 47 Hierarchical Inheritance of Permissions for Content Libraries 48 Content Library Administrator Role 50 Create a Library 50 Edit a Content Library 52 Configure Advanced Content Library Settings 54 Managing a Publisher Local Library 55 Create a Subscription for a Local Library 57 Publish the Contents of a Library to a Subscriber 58 VMware, Inc. -
CIS 3207 - Operating Systems CPU Mode
CIS 3207 - Operating Systems CPU Mode Professor Qiang Zeng Spring 2018 CPU Modes • Two common modes – Kernel mode • The CPU has to be in this mode to execute the kernel code – User mode • The CPU has to be in this mode to execute the user code CIS 3207 – Operating Systems 2 Important questions • How are CPU modes implemented? • Why are CPU modes needed? • Difference between Kernel mode and User mode • How are system calls implemented? • Advanced topic: Virtualization CIS 3207 – Operating Systems 3 How CPU Modes are implemented • Implemented through protection rings – A modern CPU typical provides different protection rings, which represent different privilege levels • A ring with a lower number has higher privileges – Introduced by Multics in 60’s – E.g., an X86 CPU usually provides four rings, and a Linux/Unix/Windows OS uses Ring 0 for the kernel mode and Ring 3 for the user mode CIS 3207 – Operating Systems 4 Why are Protection Rings needed? • Fault isolation: a fault (e.g., divided by 0) in the code running in a less-privileged ring can be captured and handled by code in a more-privileged ring • Privileged instructions: certain instructions can only be issued in a privileged ring; thus an OS can implement resource management and isolation here • Privileged memory space: certain memory can only be accessed in a privileged ring All these are demonstrated in the difference between the kernel mode and the user mode CIS 3207 – Operating Systems 5 Kernel Mode vs. User Mode? • A fault in the user space (e.g., divided by zero, invalid access,