A Secure Computing Platform for Building Automation Using Microkernel-Based Operating Systems Xiaolong Wang University of South Florida, [email protected]
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Demystifying the Real-Time Linux Scheduling Latency
Demystifying the Real-Time Linux Scheduling Latency Daniel Bristot de Oliveira Red Hat, Italy [email protected] Daniel Casini Scuola Superiore Sant’Anna, Italy [email protected] Rômulo Silva de Oliveira Universidade Federal de Santa Catarina, Brazil [email protected] Tommaso Cucinotta Scuola Superiore Sant’Anna, Italy [email protected] Abstract Linux has become a viable operating system for many real-time workloads. However, the black-box approach adopted by cyclictest, the tool used to evaluate the main real-time metric of the kernel, the scheduling latency, along with the absence of a theoretically-sound description of the in-kernel behavior, sheds some doubts about Linux meriting the real-time adjective. Aiming at clarifying the PREEMPT_RT Linux scheduling latency, this paper leverages the Thread Synchronization Model of Linux to derive a set of properties and rules defining the Linux kernel behavior from a scheduling perspective. These rules are then leveraged to derive a sound bound to the scheduling latency, considering all the sources of delays occurring in all possible sequences of synchronization events in the kernel. This paper also presents a tracing method, efficient in time and memory overheads, to observe the kernel events needed to define the variables used in the analysis. This results in an easy-to-use tool for deriving reliable scheduling latency bounds that can be used in practice. Finally, an experimental analysis compares the cyclictest and the proposed tool, showing that the proposed method can find sound bounds faster with acceptable overheads. 2012 ACM Subject Classification Computer systems organization → Real-time operating systems Keywords and phrases Real-time operating systems, Linux kernel, PREEMPT_RT, Scheduling latency Digital Object Identifier 10.4230/LIPIcs.ECRTS.2020.9 Supplementary Material ECRTS 2020 Artifact Evaluation approved artifact available at https://doi.org/10.4230/DARTS.6.1.3. -
A Programmable Microkernel for Real-Time Systems∗
A Programmable Microkernel for Real-Time Systems∗ Christoph M. Kirsch Marco A.A. Sanvido Thomas A. Henzinger University of Salzburg VMWare Inc. EPFL and UC Berkeley [email protected] tah@epfl.ch ABSTRACT Categories and Subject Descriptors We present a new software system architecture for the im- D.4.7 [Operating Systems]: Organization and Design— plementation of hard real-time applications. The core of the Real-time systems and embedded systems system is a microkernel whose reactivity (interrupt handling as in synchronous reactive programs) and proactivity (task General Terms scheduling as in traditional RTOSs) are fully programma- Languages ble. The microkernel, which we implemented on a Strong- ARM processor, consists of two interacting domain-specific Keywords virtual machines, a reactive E (Embedded) machine and a proactive S (Scheduling) machine. The microkernel code (or Real Time, Operating System, Virtual Machine microcode) that runs on the microkernel is partitioned into E and S code. E code manages the interaction of the system 1. INTRODUCTION with the physical environment: the execution of E code is In [9], we advocated the E (Embedded) machine as a triggered by environment interrupts, which signal external portable target for compiling hard real-time code, and in- events such as the arrival of a message or sensor value, and it troduced, in [11], the S (Scheduling) machine as a universal releases application tasks to the S machine. S code manages target for generating schedules according to arbitrary and the interaction of the system with the processor: the exe- possibly non-trivial strategies such as nonpreemptive and cution of S code is triggered by hardware interrupts, which multiprocessor scheduling. -
The Design of the EMPS Multiprocessor Executive for Distributed Computing
The design of the EMPS multiprocessor executive for distributed computing Citation for published version (APA): van Dijk, G. J. W. (1993). The design of the EMPS multiprocessor executive for distributed computing. Technische Universiteit Eindhoven. https://doi.org/10.6100/IR393185 DOI: 10.6100/IR393185 Document status and date: Published: 01/01/1993 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. -
Interrupt Handling in Linux
Department Informatik Technical Reports / ISSN 2191-5008 Valentin Rothberg Interrupt Handling in Linux Technical Report CS-2015-07 November 2015 Please cite as: Valentin Rothberg, “Interrupt Handling in Linux,” Friedrich-Alexander-Universitat¨ Erlangen-Nurnberg,¨ Dept. of Computer Science, Technical Reports, CS-2015-07, November 2015. Friedrich-Alexander-Universitat¨ Erlangen-Nurnberg¨ Department Informatik Martensstr. 3 · 91058 Erlangen · Germany www.cs.fau.de Interrupt Handling in Linux Valentin Rothberg Distributed Systems and Operating Systems Dept. of Computer Science, University of Erlangen, Germany [email protected] November 8, 2015 An interrupt is an event that alters the sequence of instructions executed by a processor and requires immediate attention. When the processor receives an interrupt signal, it may temporarily switch control to an inter- rupt service routine (ISR) and the suspended process (i.e., the previously running program) will be resumed as soon as the interrupt is being served. The generic term interrupt is oftentimes used synonymously for two terms, interrupts and exceptions [2]. An exception is a synchronous event that occurs when the processor detects an error condition while executing an instruction. Such an error condition may be a devision by zero, a page fault, a protection violation, etc. An interrupt, on the other hand, is an asynchronous event that occurs at random times during execution of a pro- gram in response to a signal from hardware. A proper and timely handling of interrupts is critical to the performance, but also to the security of a computer system. In general, interrupts can be emitted by hardware as well as by software. Software interrupts (e.g., via the INT n instruction of the x86 instruction set architecture (ISA) [5]) are means to change the execution context of a program to a more privileged interrupt context in order to enter the kernel and, in contrast to hardware interrupts, occur synchronously to the currently running program. -
Quantifying Security Impact of Operating-System Design
Copyright Notice School of Computer Science & Engineering COMP9242 Advanced Operating Systems These slides are distributed under the Creative Commons Attribution 3.0 License • You are free: • to share—to copy, distribute and transmit the work • to remix—to adapt the work • under the following conditions: 2019 T2 Week 09b • Attribution: You must attribute the work (but not in any way that Local OS Research suggests that the author endorses you or your use of the work) as @GernotHeiser follows: “Courtesy of Gernot Heiser, UNSW Sydney” The complete license text can be found at http://creativecommons.org/licenses/by/3.0/legalcode 1 COMP9242 2019T2 W09b: Local OS Research © Gernot Heiser 2019 – CC Attribution License Quantifying OS-Design Security Impact Approach: • Examine all critical Linux CVEs (vulnerabilities & exploits database) • easy to exploit 115 critical • high impact Linux CVEs Quantifying Security Impact of • no defence available to Nov’17 • confirmed Operating-System Design • For each establish how microkernel-based design would change impact 2 COMP9242 2019T2 W09b: Local OS Research © Gernot Heiser 2019 – CC Attribution License 3 COMP9242 2019T2 W09b: Local OS Research © Gernot Heiser 2019 – CC Attribution License Hypothetical seL4-based OS Hypothetical Security-Critical App Functionality OS structured in isolated components, minimal comparable Trusted inter-component dependencies, least privilege to Linux Application computing App requires: base • IP networking Operating system Operating system • File storage xyz xyz • Display -
Ebook - Informations About Operating Systems Version: August 15, 2006 | Download
eBook - Informations about Operating Systems Version: August 15, 2006 | Download: www.operating-system.org AIX Internet: AIX AmigaOS Internet: AmigaOS AtheOS Internet: AtheOS BeIA Internet: BeIA BeOS Internet: BeOS BSDi Internet: BSDi CP/M Internet: CP/M Darwin Internet: Darwin EPOC Internet: EPOC FreeBSD Internet: FreeBSD HP-UX Internet: HP-UX Hurd Internet: Hurd Inferno Internet: Inferno IRIX Internet: IRIX JavaOS Internet: JavaOS LFS Internet: LFS Linspire Internet: Linspire Linux Internet: Linux MacOS Internet: MacOS Minix Internet: Minix MorphOS Internet: MorphOS MS-DOS Internet: MS-DOS MVS Internet: MVS NetBSD Internet: NetBSD NetWare Internet: NetWare Newdeal Internet: Newdeal NEXTSTEP Internet: NEXTSTEP OpenBSD Internet: OpenBSD OS/2 Internet: OS/2 Further operating systems Internet: Further operating systems PalmOS Internet: PalmOS Plan9 Internet: Plan9 QNX Internet: QNX RiscOS Internet: RiscOS Solaris Internet: Solaris SuSE Linux Internet: SuSE Linux Unicos Internet: Unicos Unix Internet: Unix Unixware Internet: Unixware Windows 2000 Internet: Windows 2000 Windows 3.11 Internet: Windows 3.11 Windows 95 Internet: Windows 95 Windows 98 Internet: Windows 98 Windows CE Internet: Windows CE Windows Family Internet: Windows Family Windows ME Internet: Windows ME Seite 1 von 138 eBook - Informations about Operating Systems Version: August 15, 2006 | Download: www.operating-system.org Windows NT 3.1 Internet: Windows NT 3.1 Windows NT 4.0 Internet: Windows NT 4.0 Windows Server 2003 Internet: Windows Server 2003 Windows Vista Internet: Windows Vista Windows XP Internet: Windows XP Apple - Company Internet: Apple - Company AT&T - Company Internet: AT&T - Company Be Inc. - Company Internet: Be Inc. - Company BSD Family Internet: BSD Family Cray Inc. -
Trinity Iot Product Catalogue
IoT Devices TRINITY IOT PRODUCT CATALOGUE Teltonika Device Range 2021 TABLE OF CONTENTS 1 RUT950 27 TRB142 3 RUT955 29 TRB145 5 RUTX09 31 RUTX10 7 RUTX11 33 RUTX12 9 TRB141 35 RUTX08 11 RUT230 37 TRB255 13 RUT240 39 FMB920 15 RUT850 41 RUTXR1 17 RUT900 43 FM130 19 GH5200 45 BLUE SLIM ID 21 TRB245 47 BLUE COIN MAG 23 TSW100 49 BLUE COIN T 25 TRB140 PRODUCT SHEET / RUT950 ROUTER INTRODUCING RUT950 TRINITY APPROVED & SMART™ COMPATIBLE RUT950 is a highly reliable and secure LTE router for professional applications. Router delivers high performance, mission-critical cellular communication. RUT950 is equipped with connectivity redundancy through dual SIM failover. External antenna connectors make it possible to attach desired antennas and to easily find the best signal location. LTE LTE Cat4 Cat4 LTE Cat 4 with Dual SIM – significantly speeds up to 150 Mps reduce roaming costs WANLTE 4 LTEX failoverCat4 Cat4 Automatic switch to available 4x Ethernet ports backup connection with VLAN functionality LTE LTE Cat4 Cat4 Wireless Access Point Linux Powered with Hotspot functionality Simply order, and we’ll take care of the rest Source Import Test ICASA Management Onboarding 24/7 Platform Support www.trinity.co.za 1 PRODUCT SHEET / RUT950 ROUTER LAN Ethernet Ports WAN Ethernet Ports LTE antenna connectors Power socket WiFi antenna SIM card connectors slots Hardware Weight 256 g CPU Atheros Wasp, MIPS 74Kc, 550 MHz Memory 16 MBytes Flash, 128 MBytes DDR2 RAM Ethernet 4 x 10/100 Ethernet ports: 1 x WAN (configurable as LAN), 3 x LAN ports Power supply 9 -
Microkernels in a Bit More Depth Early Operating Systems Had Very Little Structure a Strictly Layered Approach Was Promoted by Dijkstra
Motivation Microkernels In a Bit More Depth Early operating systems had very little structure A strictly layered approach was promoted by Dijkstra THE Operating System [Dij68] COMP9242 2007/S2 Week 4 Later OS (more or less) followed that approach (e.g., Unix). UNSW Such systems are known as monolithic kernels COMP9242 07S2 W04 1 Microkernels COMP9242 07S2 W04 2 Microkernels Issues of Monolithic Kernels Evolution of the Linux Kernel E Advantages: Kernel has access to everything: all optimisations possible all techniques/mechanisms/concepts implementable Kernel can be extended by adding more code, e.g. for: new services support for new harwdare Problems: Widening range of services and applications OS bigger, more complex, slower, more error prone. Need to support same OS on different hardware. Like to support various OS environments. Distribution impossible to provide all services from same (local) kernel. COMP9242 07S2 W04 3 Microkernels COMP9242 07S2 W04 4 Microkernels Approaches to Tackling Complexity Evolution of the Linux Kernel Part 2 A Classical software-engineering approach: modularity Software-engineering study of Linux kernel [SJW+02]: (relatively) small, mostly self-contained components well-defined interfaces between them Looked at size and interdependencies of kernel "modules" enforcement of interfaces "common coupling": interdependency via global variables containment of faults to few modules Analysed development over time (linearised version number) Doesn't work with monolithic kernels: Result 1: -
Building Performance Measurement Tools for the MINIX 3 Operating System
Building Performance Measurement Tools for the MINIX 3 Operating System Rogier Meurs August 2006 Contents 1 INTRODUCTION 1 1.1 Measuring Performance 1 1.2 MINIX 3 2 2 STATISTICAL PROFILING 3 2.1 Introduction 3 2.2 In Search of a Timer 3 2.2.1 i8259 Timers 3 2.2.2 CMOS Real-Time Clock 3 2.3 High-level Description 4 2.4 Work Done in User-Space 5 2.4.1 The SPROFILE System Call 5 2.5 Work Done in Kernel-Space 5 2.5.1 The SPROF Kernel Call 5 2.5.2 Profiling using the CMOS Timer Interrupt 6 2.6 Work Done at the Application Level 7 2.6.1 Control Tool: profile 7 2.6.2 Analyzing Tool: sprofalyze.pl 7 2.7 What Can and What Cannot be Profiled 8 2.8 Profiling Results 8 2.8.1 High Scoring IPC Functions 8 2.8.2 Interrupt Delay 9 2.8.3 Profiling Runs on Simulator and Other CPU Models 12 2.9 Side-effect of Using the CMOS Clock 12 3 CALL PROFILING 13 3.1 Introduction 13 3.1.1 Compiler-supported Call Profiling 13 3.1.2 Call Paths, Call and Cycle Attribution 13 3.2 High-level Description 14 3.3 Work Done in User-Space 15 3.3.1 The CPROFILE System Call 15 3.4 Work Done in Kernel-Space 16 3.4.1 The PROFBUF and CPROF Kernel Calls 16 3.5 Work Done in Libraries 17 3.5.1 Profiling Using Library Functions 17 3.5.2 The Procentry Library Function 17 3.5.3 The Procexit Library Function 20 3.5.4 The Call Path String 22 3.5.5 Testing Overhead Elimination 23 3.6 Profiling Kernel-Space/User-Space Processes 24 3.6.1 Differences in Announcing and Table Sizes 24 3.6.2 Kernel-Space Issue: Reentrancy 26 3.6.3 Kernel-Space Issue: The Call Path 26 3.7 Work Done at the Application -
The OKL4 Microvisor: Convergence Point of Microkernels and Hypervisors
The OKL4 Microvisor: Convergence Point of Microkernels and Hypervisors Gernot Heiser, Ben Leslie Open Kernel Labs and NICTA and UNSW Sydney, Australia ok-labs.com ©2010 Open Kernel Labs and NICTA. All rights reserved. Microkernels vs Hypervisors > Hypervisors = “microkernels done right?” [Hand et al, HotOS ‘05] • Talks about “liability inversion”, “IPC irrelevance” … > What’s the difference anyway? ok-labs.com ©2010 Open Kernel Labs and NICTA. All rights reserved. 2 What are Hypervisors? > Hypervisor = “virtual machine monitor” • Designed to multiplex multiple virtual machines on single physical machine VM1 VM2 Apps Apps AppsApps AppsApps OS OS Hypervisor > Invented in ‘60s to time-share with single-user OSes > Re-discovered in ‘00s to work around broken OS resource management ok-labs.com ©2010 Open Kernel Labs and NICTA. All rights reserved. 3 What are Microkernels? > Designed to minimise kernel code • Remove policy, services, retain mechanisms • Run OS services in user-mode • Software-engineering and dependability reasons • L4: ≈ 10 kLOC, Xen ≈ 100 kLOC, Linux: ≈ 10,000 kLOC ServersServers ServersServers Apps Servers Device AppsApps Drivers Microkernel > IPC performance critical (highly optimised) • Achieved by API simplicity, cache-friendly implementation > Invented 1970 [Brinch Hansen], popularised late ‘80s (Mach, Chorus) ok-labs.com ©2010 Open Kernel Labs and NICTA. All rights reserved. 4 What’s the Difference? > Both contain all code executing at highest privilege level • Although hypervisor may contain user-mode code as well > Both need to abstract hardware resources • Hypervisor: abstraction closely models hardware • Microkernel: abstraction designed to support wide range of systems > What must be abstracted? • Memory • CPU • I/O • Communication ok-labs.com ©2010 Open Kernel Labs and NICTA. -
Amigaos 3.2 FAQ 47.1 (09.04.2021) English
$VER: AmigaOS 3.2 FAQ 47.1 (09.04.2021) English Please note: This file contains a list of frequently asked questions along with answers, sorted by topics. Before trying to contact support, please read through this FAQ to determine whether or not it answers your question(s). Whilst this FAQ is focused on AmigaOS 3.2, it contains information regarding previous AmigaOS versions. Index of topics covered in this FAQ: 1. Installation 1.1 * What are the minimum hardware requirements for AmigaOS 3.2? 1.2 * Why won't AmigaOS 3.2 boot with 512 KB of RAM? 1.3 * Ok, I get it; 512 KB is not enough anymore, but can I get my way with less than 2 MB of RAM? 1.4 * How can I verify whether I correctly installed AmigaOS 3.2? 1.5 * Do you have any tips that can help me with 3.2 using my current hardware and software combination? 1.6 * The Help subsystem fails, it seems it is not available anymore. What happened? 1.7 * What are GlowIcons? Should I choose to install them? 1.8 * How can I verify the integrity of my AmigaOS 3.2 CD-ROM? 1.9 * My Greek/Russian/Polish/Turkish fonts are not being properly displayed. How can I fix this? 1.10 * When I boot from my AmigaOS 3.2 CD-ROM, I am being welcomed to the "AmigaOS Preinstallation Environment". What does this mean? 1.11 * What is the optimal ADF images/floppy disk ordering for a full AmigaOS 3.2 installation? 1.12 * LoadModule fails for some unknown reason when trying to update my ROM modules. -
Technical Proposal for One Day Workshop on Fog and Edge
1 Technical Proposal for One Day Workshop on Fog and Edge Computing for Beyond IoT Services and Opportunities IEEE 7th World Forum on Internet of Things New Orleans, Louisiana, USA Workshop Title: Fog and Edge Computing for 6G Networks/IoT Services and Opportunities 1. Preamble As we evolve toward the Internet of Things (IoT), our 5G/6G and future mobile networks must support a much wider range of applications, including vehicular networking, automated man- ufacturing, smart cities, drones, smart grids, e-health, and the many emerging AI-enabled applications such as Virtual Reality (VR) and Augmented Reality (AR). The cloud computing plus communication pipe model is no longer adequate for supporting these emerging appli- cations. Connecting every device directly to the cloud can often be impractical due to factors such as limited resources on the devices, software and management complexity, limited net- work agility and cognition, and system scalability. In such scenarios, users will desire local services. Future mobile networks will also require computing capabilities inside or close to the radio access networks (RANs) to enable advanced networking capabilities, such as estab- lishing radio connections more timely and adjusting radio channel coding dynamically in re- sponse to changing user needs and communication environments, and allow user applica- tions to be hosted in the RANs that are closer to the users. These and the many other new requirements call for a new computing paradigm – fog/edge computing and networking. Fog/Edge envisions an open and standards-based horizontal ar- chitecture for distributing functions (from computing to storage to control and to networking functions) closer to users, not just to any specific type of network edge device but anywhere along the cloud-to-thing continuum that can best meet user requirements.