Redhawk Linux User's Guide
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Debugging Kernel Problems
Debugging Kernel Problems by GregLehey Edition for AsiaBSDCon 2004 Taipei, 13 March 2004 Debugging Kernel Problems by GregLehey([email protected]) Copyright © 1995-2004 GregLehey 3Debugging Kernel Problems Preface Debugging kernel problems is a black art. Not manypeople do it, and documentation is rare, in- accurate and incomplete. This document is no exception: faced with the choice of accuracyand completeness, I chose to attempt the latter.Asusual, time was the limiting factor,and this draft is still in beta status. This is a typical situation for the whole topic of kernel debugging: building debug tools and documentation is expensive,and the people who write them are also the people who use them, so there'satendencytobuild as much of the tool as necessary to do the job at hand. If the tool is well-written, it will be reusable by the next person who looks at a particular area; if not, it might fall into disuse. Consider this book a starting point for your own develop- ment of debugging tools, and remember: more than anywhere else, this is an area with ``some as- sembly required''. Debugging Kernel Problems 4 1 Introduction Operating systems fail. All operating systems contain bugs, and theywill sometimes cause the system to behave incorrectly.The BSD kernels are no exception. Compared to most other oper- ating systems, both free and commercial, the BSD kernels offer a large number of debugging tools. This tutorial examines the options available both to the experienced end user and also to the developer. In this tutorial, we’ll look at the following topics: • Howand whykernels fail. -
Linux Kernel and Driver Development Training Slides
Linux Kernel and Driver Development Training Linux Kernel and Driver Development Training © Copyright 2004-2021, Bootlin. Creative Commons BY-SA 3.0 license. Latest update: October 9, 2021. Document updates and sources: https://bootlin.com/doc/training/linux-kernel Corrections, suggestions, contributions and translations are welcome! embedded Linux and kernel engineering Send them to [email protected] - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 1/470 Rights to copy © Copyright 2004-2021, Bootlin License: Creative Commons Attribution - Share Alike 3.0 https://creativecommons.org/licenses/by-sa/3.0/legalcode You are free: I to copy, distribute, display, and perform the work I to make derivative works I to make commercial use of the work Under the following conditions: I Attribution. You must give the original author credit. I Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one. I For any reuse or distribution, you must make clear to others the license terms of this work. I Any of these conditions can be waived if you get permission from the copyright holder. Your fair use and other rights are in no way affected by the above. Document sources: https://github.com/bootlin/training-materials/ - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 2/470 Hyperlinks in the document There are many hyperlinks in the document I Regular hyperlinks: https://kernel.org/ I Kernel documentation links: dev-tools/kasan I Links to kernel source files and directories: drivers/input/ include/linux/fb.h I Links to the declarations, definitions and instances of kernel symbols (functions, types, data, structures): platform_get_irq() GFP_KERNEL struct file_operations - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 3/470 Company at a glance I Engineering company created in 2004, named ”Free Electrons” until Feb. -
Appendix B Development Tools
Appendix B Development Tools Problem Statement Although more proprietary packages are available, there are abundant open source packages, giving its users unprecedented flexibility and freedom of choice, that most users can find an application that exactly meets their needs. However, it is also this pool of choices that drive individuals to share a wide range of preferences and biases. As a result, Linux/Open source packages (and softeware in general) is flooded with religious wars over programming languages, editors, licences, etc. Some are worthwhile debates, others are meaningless flamewars. Throughout Appendix B and next chapter, Appendix C, we intend to summarize a few essential tools (from our point of view) that may help readers to know the aspects and how-to of (1) development tools including programming, debugging, and maintaining, and (2) network experiment tools including name-addressing, perimeter probing, traffic-monitoring, benchmarking, simulating/emulating, and finally hacking. Section B.1 guides readers to begin the developing journey with programming tools. A good first step would be writing the first piece of codes using a Visual Improved (vim) text editor. Then compiling it to binary executables with GNU C compiler (gcc), and furthermore offloading some repetitive compiling steps to the make utility. The old 80/20 rule still works on programming where 80% of your codes come from 20% of your efforts leaving 80% of your efforts go buggy about your program. Therefore you would need some debugging tools as dicussed in Section 1.2. including source-level debugging, GNU Debugger (gdb), or a GUI fasion approach, Data Display Debugger (ddd), and debug the kernel itself using remote Kernel GNU Debugger (kgdb). -
Devt: Let the Device Talk
Iowa State University Capstones, Theses and Creative Components Dissertations Summer 2020 DevT: Let the Device Talk Chander Bhushan Gupta Follow this and additional works at: https://lib.dr.iastate.edu/creativecomponents Part of the Data Storage Systems Commons Recommended Citation Gupta, Chander Bhushan, "DevT: Let the Device Talk" (2020). Creative Components. 585. https://lib.dr.iastate.edu/creativecomponents/585 This Creative Component is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Creative Components by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. DevT: Let the Device Talk by Chander Bhushan Gupta A Creative Component submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Computer Engineering Program of Study Committee: Mai Zheng, Major Professor The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this creative component. The Graduate College will ensure this creative component is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2020 Copyright c Chander Bhushan Gupta, 2020. All rights reserved. ii TABLE OF CONTENTS Page LIST OF TABLES . iv LIST OF FIGURES . .v ACKNOWLEDGMENTS . vii ABSTRACT . viii CHAPTER 1. INTRODUCTION . .1 1.1 Motivation . .3 1.2 Related Work . .5 1.3 Outline . .6 CHAPTER 2. REVIEW OF LITERATURE . .7 2.1 Why FEMU? . -
Thread Scheduling in Multi-Core Operating Systems Redha Gouicem
Thread Scheduling in Multi-core Operating Systems Redha Gouicem To cite this version: Redha Gouicem. Thread Scheduling in Multi-core Operating Systems. Computer Science [cs]. Sor- bonne Université, 2020. English. tel-02977242 HAL Id: tel-02977242 https://hal.archives-ouvertes.fr/tel-02977242 Submitted on 24 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Ph.D thesis in Computer Science Thread Scheduling in Multi-core Operating Systems How to Understand, Improve and Fix your Scheduler Redha GOUICEM Sorbonne Université Laboratoire d’Informatique de Paris 6 Inria Whisper Team PH.D.DEFENSE: 23 October 2020, Paris, France JURYMEMBERS: Mr. Pascal Felber, Full Professor, Université de Neuchâtel Reviewer Mr. Vivien Quéma, Full Professor, Grenoble INP (ENSIMAG) Reviewer Mr. Rachid Guerraoui, Full Professor, École Polytechnique Fédérale de Lausanne Examiner Ms. Karine Heydemann, Associate Professor, Sorbonne Université Examiner Mr. Etienne Rivière, Full Professor, University of Louvain Examiner Mr. Gilles Muller, Senior Research Scientist, Inria Advisor Mr. Julien Sopena, Associate Professor, Sorbonne Université Advisor ABSTRACT In this thesis, we address the problem of schedulers for multi-core architectures from several perspectives: design (simplicity and correct- ness), performance improvement and the development of application- specific schedulers. -
Linux Update
Linux Kernel Debugging Tools Jason Wessel - Product Architect for WR Linux Core Runtime - Kernel.org KGDB Maintainer June 23th, 2010 Agenda • Talk about a number of common kernel debugging tools • Describe high level tactics for using kernel debugging tools • Demonstrate using several tools The harsh reality is you could spend a whole day or more talking about each tool. *** Later find slides/code at: http://kgdb.wiki.kernel.org *** 2 © 2010 Wind River Exciting news • For 2.6.35-rc1 – kdb (the kernel debug shell) merged to mainline! – Ability to debug before console_init() – You can use the EHCI debug port with kgdb • There are thoughts about next few years of kgdb/kdb – Implement complete atomic kernel mode setting – Continue to improve the non ehci debug usb console – Improve keyboard panic handler – Further integration with kprobes and hw assisted debugging – netconsole / kgdboe v2 – Use dedicated HW queues • The only bad news is it takes a long time to get there. 3 © 2010 Wind River Is there anything better than kgdb? • Good – kgdb / kdb • Better – QEMU/KVM backend debugger – Virtual box backend debugger – vmware backend debugger – kdump/kexec • Best – ICE (usb or ethernet) – Simics (because it has backward stepping) • In a class by itself – printk() / trace_printk() The challenge is knowing what to use when... Working tools rock! 4 © 2010 Wind River A bit about printk() and timing • printk is probably the #1 most reliable debug • Any seasoned kernel developer has surely experienced: – Add a printk and the bug goes away! – Timing in -
Kshot: Live Kernel Patching with SMM and SGX
KShot: Live Kernel Patching with SMM and SGX Lei Zhou∗y, Fengwei Zhang∗, Jinghui Liaoz, Zhengyu Ning∗, Jidong Xiaox Kevin Leach{, Westley Weimer{ and Guojun Wangk ∗Department of Computer Science and Engineering, Southern University of Science and Technology, Shenzhen, China, zhoul2019,zhangfw,ningzy2019 @sustech.edu.cn f g ySchool of Computer Science and Engineering, Central South University, Changsha, China zDepartment of Computer Science, Wayne State University, Detroit, USA, [email protected] xDepartment of Computer Science, Boise State University, Boise, USA, [email protected] Department of Computer Science and Engineering, University of Michigan, Ann Arbor, USA, kjleach,weimerw @umich.edu { f g kSchool of Computer Science and Cyber Engineering, Guangzhou University, Guangzhou, China, [email protected] Abstract—Live kernel patching is an increasingly common kernel vulnerabilities also merit patching. Organizations often trend in operating system distributions, enabling dynamic up- use rolling upgrades [3], [6], in which patches are designed dates to include new features or to fix vulnerabilities without to affect small subsystems that minimize unplanned whole- having to reboot the system. Patching the kernel at runtime lowers downtime and reduces the loss of useful state from running system downtime, to update and patch whole server systems. applications. However, existing kernel live patching techniques However, rolling upgrades do not altogether obviate the need (1) rely on specific support from the target operating system, to restart software or reboot systems; instead, dynamic hot and (2) admit patch failures resulting from kernel faults. We patching (live patching) approaches [7]–[9] aim to apply present KSHOT, a kernel live patching mechanism based on patches to running software without having to restart it. -
Red Hat Enterprise Linux 7 Kernel Administration Guide
Red Hat Enterprise Linux 7 Kernel Administration Guide Examples of Tasks for Managing the Kernel Last Updated: 2018-05-21 Red Hat Enterprise Linux 7 Kernel Administration Guide Examples of Tasks for Managing the Kernel Marie Dolezelova Red Hat Customer Content Services [email protected] Mark Flitter Red Hat Customer Content Services Douglas Silas Red Hat Customer Content Services Eliska Slobodova Red Hat Customer Content Services Jaromir Hradilek Red Hat Customer Content Services Maxim Svistunov Red Hat Customer Content Services Robert Krátký Red Hat Customer Content Services Stephen Wadeley Red Hat Customer Content Services Florian Nadge Red Hat Customer Content Services Legal Notice Copyright © 2018 Red Hat, Inc. The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/ . In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux ® is the registered trademark of Linus Torvalds in the United States and other countries. Java ® is a registered trademark of Oracle and/or its affiliates. -
Using Kgdb and the Kgdb Internals.Pdf
Using kgdb and the kgdb Internals Jason Wessel [email protected] Tom Rini [email protected] Amit S. Kale [email protected] Using kgdb and the kgdb Internals by Jason Wessel by Tom Rini by Amit S. Kale Copyright © 2008 Wind River Systems, Inc. Copyright © 2004-2005 MontaVista Software, Inc. Copyright © 2004 Amit S. Kale This file is licensed under the terms of the GNU General Public License version 2. This program is licensed "as is" without any warranty of any kind, whether express or implied. Table of Contents 1. Introduction............................................................................................................................................1 2. Compiling a kernel.................................................................................................................................2 3. Enable kgdb for debugging...................................................................................................................3 3.1. Kernel parameter: kgdbwait........................................................................................................3 3.2. Kernel parameter: kgdboc...........................................................................................................3 3.2.1. Using kgdboc..................................................................................................................3 3.3. Kernel parameter: kgdbcon.........................................................................................................4 4. Connecting gdb......................................................................................................................................6 -
Red Hat Enterprise Linux 8 Managing, Monitoring and Updating the Kernel
Red Hat Enterprise Linux 8 Managing, monitoring and updating the kernel A guide to managing the Linux kernel on Red Hat Enterprise Linux 8 Last Updated: 2019-11-05 Red Hat Enterprise Linux 8 Managing, monitoring and updating the kernel A guide to managing the Linux kernel on Red Hat Enterprise Linux 8 Legal Notice Copyright © 2019 Red Hat, Inc. The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/ . In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, the Red Hat logo, JBoss, OpenShift, Fedora, the Infinity logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux ® is the registered trademark of Linus Torvalds in the United States and other countries. Java ® is a registered trademark of Oracle and/or its affiliates. XFS ® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries. MySQL ® is a registered trademark of MySQL AB in the United States, the European Union and other countries. -
Understanding the Linux Virtual Memory Manager
1 Understanding The Linux Virtual Memory Manager Mel Gorman 15th February 2004 Contents List of Figures 5 List of Tables 7 Acknowledgements 9 1 Introduction 12 1.1 General Kernel Literature . 13 1.2 Thesis Overview . 14 1.3 Typographic Conventions . 14 1.4 About this Document . 14 1.5 Companion CD . 15 2 Code Management 17 2.1 Managing the Source . 17 2.2 Getting Started . 23 2.3 Submitting Work . 24 3 Describing Physical Memory 26 3.1 Nodes . 27 3.2 Zones . 29 3.3 Pages . 31 3.4 High Memory . 33 4 Page Table Management 36 4.1 Describing the Page Directory . 37 4.2 Describing a Page Table Entry . 38 4.3 Using Page Table Entries . 39 4.4 Translating and Setting Page Table Entries . 42 4.5 Allocating and Freeing Page Tables . 42 4.6 Kernel Page Tables . 43 4.7 Mapping addresses to struct pages .................. 44 5 Process Address Space 47 5.1 Linear Address Space . 48 5.2 Managing the Address Space . 49 2 CONTENTS 3 5.3 Process Address Space Descriptor . 50 5.4 Memory Regions . 55 5.5 Exception Handling . 70 5.6 Page Faulting . 71 5.7 Copying To/From Userspace . 77 6 Boot Memory Allocator 80 6.1 Representing the Boot Map . 81 6.2 Initialising the Boot Memory Allocator . 81 6.3 Allocating Memory . 83 6.4 Freeing Memory . 85 6.5 Retiring the Boot Memory Allocator . 85 7 Physical Page Allocation 90 7.1 Managing Free Blocks . 90 7.2 Allocating Pages . 91 7.3 Free Pages . -
Using Serial Kdb / Kgdb to Debug the Linux Kernel
Using Serial kdb / kgdb to Debug the Linux Kernel Doug Anderson, Google Chrome OS Intro Chrome OS About Me ● Random kernel Engineer at Google working on Chrome OS. ● I like debugging. ● I like debuggers. ● Not the author nor maintainer of kdb / kgdb, but I fix bugs sometimes. ● I really only have deep experience with Linux on arm32 / arm64. Chrome OS About You ● You're a kernel Engineer. ● You sometimes run into crashes / hangs / bugs on devices you're working on. ● You have a serial connection to the device you're working on. ○ There are other ways to talk to kdb / kgdb, but I won't cover those. ● You're here in person (or watching a video), since much of this will be demo. ● You like to go for long romantic walks through the woods at night. Chrome OS Syllabus ● What is kdb / kgdb? ● What kdb / kgdb are best suited for ● Comparison to similar tools ● Getting setup ● Debugging your first problem ● Debugging your second problem ● Next steps Chrome OS What is kdb / kgdb? ● The docs are the authority. https://www.kernel.org/doc/html/v5.2/dev-tools/kgdb.html ● kdb = The Kernel DeBugger. A simple shell that can do simple peeks/pokes but also has commands that can print kernel state at time of crash. ● kgdb = The Kernel GDB server. Allows a second computer to run GDB and debug the kernel. Chrome OS Do I want kdb, or kgdb? ● Before my time, I believe you had to pick. Now, you can have both. ● kgdb just lets you use vanilla gdb to debug the kernel.