The document provides an overview of the Linux kernel internals including:
1) The Linux kernel architecture adopts a monolithic design that provides stability, safety, and high performance while maintaining advantages of both monolithic and microkernel approaches.
2) Key kernel components include processes and threads management, memory management using paging and segmentation, file systems, networking, and device drivers.
3) The kernel uses inodes and blocks to organize file system data on disk and supports various file systems like Ext2 through a virtual file system interface.
The document provides an overview of the Linux kernel architecture and processes. It discusses key kernel concepts like the monolithic kernel design, system calls, loadable modules, virtual memory, and preemptive multitasking. It also covers kernel functions, layers, and context switching between processes. The CPU scheduler, multi-threading, inter-process communication techniques, and tunable kernel parameters are summarized as well.
The document provides an overview of the Linux architecture including:
1) It discusses the history of Linux from its origins as a free UNIX-like operating system developed by Linus Torvalds to the over 18 million lines of code it contains today.
2) It describes the key components of the Linux system architecture including the hardware layer, kernel, shell, and utilities. The kernel acts as the core of the OS and interacts with hardware to perform low-level services.
3) It outlines several important kernel functions including file system management, process management and scheduling, memory management, and device drivers which allow communication with I/O devices through device files.
This document provides an overview of the Linux kernel, including its history, structure, build process, installation, updating, and customization. It discusses getting the kernel source code, configuring and building the kernel, installing modules and the kernel, applying updates via patches, and determining the correct driver for PCI devices by matching the vendor and device IDs. The key steps are to find the PCI IDs, search for the IDs in kernel headers to identify the driver, search the kernel makefiles and configuration to enable that driver for compilation.
The document summarizes the architecture of the Linux operating system. It discusses the main components of Linux including the kernel, process management, memory management, file systems, device drivers, network stack, and architecture-dependent code. The kernel is at the core and acts as a resource manager. It uses a monolithic design. Process and memory management are handled via data structures like task_struct and buddy allocation. Virtual memory is implemented using page tables. File systems organize files in a hierarchy with inodes. Device drivers interface with hardware. The network stack follows a layered model. Architecture code is separated by subdirectory.
The document provides an introduction to Linux and device drivers. It discusses Linux directory structure, kernel components, kernel modules, character drivers, and registering drivers. Key topics include dynamically loading modules, major and minor numbers, private data, and communicating with hardware via I/O ports and memory mapping.
Part 02 Linux Kernel Module ProgrammingTushar B Kute
Presentation on "Linux Kernel Module Programming".
Presented at Army Institute of Technology, Pune for FDP on "Basics of Linux Kernel Programming". by Tushar B Kute (http://tusharkute.com).
The document discusses the architecture of the Linux kernel. It describes the user space and kernel space components. In user space are the user applications, glibc library, and each process's virtual address space. In kernel space are the system call interface, architecture-independent kernel code, and architecture-dependent code. It then covers several kernel subsystems like process management, memory management, virtual file system, network stack, and device drivers.
The document provides an overview of the Linux kernel architecture and processes. It discusses key kernel concepts like the monolithic kernel design, system calls, loadable modules, virtual memory, and preemptive multitasking. It also covers kernel functions, layers, and context switching between processes. The CPU scheduler, multi-threading, inter-process communication techniques, and tunable kernel parameters are summarized as well.
The document provides an overview of the Linux architecture including:
1) It discusses the history of Linux from its origins as a free UNIX-like operating system developed by Linus Torvalds to the over 18 million lines of code it contains today.
2) It describes the key components of the Linux system architecture including the hardware layer, kernel, shell, and utilities. The kernel acts as the core of the OS and interacts with hardware to perform low-level services.
3) It outlines several important kernel functions including file system management, process management and scheduling, memory management, and device drivers which allow communication with I/O devices through device files.
This document provides an overview of the Linux kernel, including its history, structure, build process, installation, updating, and customization. It discusses getting the kernel source code, configuring and building the kernel, installing modules and the kernel, applying updates via patches, and determining the correct driver for PCI devices by matching the vendor and device IDs. The key steps are to find the PCI IDs, search for the IDs in kernel headers to identify the driver, search the kernel makefiles and configuration to enable that driver for compilation.
The document summarizes the architecture of the Linux operating system. It discusses the main components of Linux including the kernel, process management, memory management, file systems, device drivers, network stack, and architecture-dependent code. The kernel is at the core and acts as a resource manager. It uses a monolithic design. Process and memory management are handled via data structures like task_struct and buddy allocation. Virtual memory is implemented using page tables. File systems organize files in a hierarchy with inodes. Device drivers interface with hardware. The network stack follows a layered model. Architecture code is separated by subdirectory.
The document provides an introduction to Linux and device drivers. It discusses Linux directory structure, kernel components, kernel modules, character drivers, and registering drivers. Key topics include dynamically loading modules, major and minor numbers, private data, and communicating with hardware via I/O ports and memory mapping.
Part 02 Linux Kernel Module ProgrammingTushar B Kute
Presentation on "Linux Kernel Module Programming".
Presented at Army Institute of Technology, Pune for FDP on "Basics of Linux Kernel Programming". by Tushar B Kute (http://tusharkute.com).
The document discusses the architecture of the Linux kernel. It describes the user space and kernel space components. In user space are the user applications, glibc library, and each process's virtual address space. In kernel space are the system call interface, architecture-independent kernel code, and architecture-dependent code. It then covers several kernel subsystems like process management, memory management, virtual file system, network stack, and device drivers.
The document provides an overview of the key components of the Linux operating system, including:
1) The Linux kernel, which acts as a resource manager for processes, memory, and hardware devices.
2) Process and memory management systems that control how processes are allocated and memory is allocated and freed.
3) The file system which organizes how files are stored and accessed.
4) Device drivers that allow the operating system to interface with hardware.
5) The network stack which handles network protocols and connections.
6) Architecture-dependent code that provides hardware-specific implementations of core functions.
The document discusses the Linux kernel and its structure. The Linux kernel acts as the interface between hardware and software, contains device drivers for peripherals, handles resource allocation and tracking application access to files. It is also responsible for security and access controls for users. The kernel version numbers use even numbers to indicate stable releases.
The document provides an overview of the Linux kernel architecture. It discusses that the kernel includes modules/subsystems that provide operating system functions and forms the core of the OS. It describes the kernel's user space and kernel space, with user processes running in user space and kernel processes running in kernel space. System calls are used to pass arguments between the spaces. The document also summarizes several key kernel functions, including the file system, process management, device drivers, memory management, and networking.
The Linux Kernel Implementation of Pipes and FIFOsDivye Kapoor
A walkthrough of the code structure used in the linux kernel to implement pipes and FIFOs.
This was presented to a Senior level class at the Indian Institute of Technology, Roorkee.
This document discusses kernel modules in Linux. It begins by defining the kernel as the central part of the operating system that manages processes, memory, devices, and storage. Kernel modules allow new functionality to be added to the kernel at runtime without rebooting. Common module commands like insmod, lsmod and rmmod are described. The document outlines how modules are loaded and unloaded by the kernel and provides a simple "hello world" example of a kernel module.
Linux device drivers act as an interface between hardware devices and user programs. They communicate with hardware devices and expose an interface to user applications through system calls. Device drivers can be loaded as kernel modules and provide access to devices through special files in the /dev directory. Common operations for drivers include handling read and write requests either through interrupt-driven or polling-based I/O.
This presentation gives introduction to kernel module programming with sample kernel module.
It helps to start with kernel programming and how it can be used to develop various types of device drivers.
Quontra Solutions offers Job oriented Linux online training with updated technologies. For more info about our Linux online training contact us directly. We are providing Linux online training to all students throughout worldwide by real time faculties. Our Linux training strengthens your skills and knowledge which will helps you to gain a competitive advantage in starting your career. Outclasses will help you to gain knowledge on real time scenario. It will be most use full to boost up your career.
Our training sessions are designed in such a way that all the students can be convenient with the training schedules and course timings.
Along with Training, we also conduct several mock interviews along with Job Placement Assistance. Attend Free Demo before joining the class.
Our Features:
• Real world projects to get practical based experience
• Online tests to explore the resource learning
• Experienced certified trainers as instructors
• One to one personalized training with desktop access
• Case studies and state of art library to access study material
• Resume build assistance to win in interviews
Contact us:
Simson Andrew
Email: info@quontrasolutions.com
web: www.quontrasolutions.com
This document outlines the key components of a Linux character device driver, including modules, major and minor numbers, data structures like struct file and struct file_operations, driver registration, and core functions like open, release, read and write. It provides an introduction to character device drivers in Linux and their basic architecture.
This presentation gives an overview of Linux kernel block I/O susbsystem functionality, importance of I/O schedulers in Block layer. It also describes the different types of I/O Schedulers including the Deadline I/O scheduler, Anticipatory I/O Scheduler, Complete Fair queuing I/O scheduler and Noop I/O scheduler.
Some basic knowledges required for beginners in writing linux kernel module - with a description of linux source tree, so that the idea of where and how develops. The working of insmod and rmmod commands are described also.
This document provides an overview of the Linux architecture. It describes Linux as a free UNIX-like kernel that forms the GNU/Linux operating system together with the GNU project software. The kernel acts as an intermediary between hardware and software, managing processes, scheduling, and resources. Processes can be in different states like running, waiting, or sleeping. The kernel uses preemptive multitasking to switch between processes and prioritize interrupts. System calls allow processes to be created and managed.
This document provides an introduction to the Linux kernel, including its main features and architecture. It discusses the kernel's portable, open source, multi-user nature and hierarchical file system. The document outlines the Linux versioning scheme and describes the kernel's main subsystems, including process management, memory management, the virtual file system, network stack, and system call interface. It explains how the kernel uses virtual memory to separate user space and privileged kernel space.
This document provides an introduction to Linux device drivers. It discusses that device drivers provide an abstraction layer between software and hardware, hiding hardware details. It describes different types of devices like character and block devices. It covers key concepts like loadable modules, driver entry/exit points, interrupts, deferred work, and memory-mapped peripherals. The document uses serial/UART drivers and the TTY layer as examples to illustrate driver concepts.
There are three ARM core variants for memory models:
- Flat memory model provides direct access to all memory but is not suitable for multi-tasking. Examples are ARM7TDMI and ARM7EJ-S.
- Memory Protection Unit (MPU) uses regions of memory to actively protect system resources for multi-tasking platforms. Examples are ARM946E-S.
- Memory Management Unit (MMU) provides protection of resources and enables virtual memory. The ARM1026EJ-S uses an MMU.
The document provides an introduction to Linux kernel modules. It discusses that kernel modules extend the capabilities of the Linux kernel by executing code as part of the kernel. It then describes the anatomy of a kernel module, including initialization and cleanup functions. The document demonstrates a simple "hello world" kernel module example and how to build, load and unload kernel modules. It also introduces the idea of character device drivers as a more advanced kernel module example.
The document provides an overview of the initialization phase of the Linux kernel. It discusses how the kernel enables paging to transition from physical to virtual memory addresses. It then describes the various initialization functions that are called by start_kernel to initialize kernel features and architecture-specific code. Some key initialization tasks discussed include creating an identity page table, clearing BSS, and reserving BIOS memory.
The document discusses Linux device drivers, including how they interface between user programs and hardware using a file interface, are implemented as loadable kernel modules (LKMs) that are inserted into the kernel, and how common operations like open, read, write, and release are mapped to kernel functions through a file operations structure.
The document is a presentation by Vivek Kurmi about the Linux Install Fest-2012 event on October 16th, 2012. It provides an introduction to Linux, discussing that it is free and open source, runs on multiple hardware platforms, and has many flavors due to its open source nature. It covers the history of Linux from UNIX to GNU to Linux's creation in 1991. It also highlights advantages of Linux and examples of organizations that use Linux.
Overview of the Linux Kernel, based on "Anatomy of the Linux Kernel" by M. Tim Jones, (IBM Developerworks) http://www.ibm.com/developerworks/linux/library/l-linux-kernel/
Kernel Recipes 2015: Kernel packet capture technologiesAnne Nicolas
Sniffing through the ages
Capturing packets running on the wire to send them to a software doing analysis seems at first sight a simple tasks. But one has not to forget that with current network this can means capturing 30M packets per second. The objective of this talk is to show what methods and techniques have been implemented in Linux and how they have evolved over time.
The talk will cover AF_PACKET capture as well as PF_RING, dpdk and netmap. It will try to show how the various evolution of hardware and software have had an impact on the design of these technologies. Regarding software a special focus will be made on Suricata IDS which is implementing most of these capture methods.
Eric Leblond, Stamus Networks
The document provides an overview of the key components of the Linux operating system, including:
1) The Linux kernel, which acts as a resource manager for processes, memory, and hardware devices.
2) Process and memory management systems that control how processes are allocated and memory is allocated and freed.
3) The file system which organizes how files are stored and accessed.
4) Device drivers that allow the operating system to interface with hardware.
5) The network stack which handles network protocols and connections.
6) Architecture-dependent code that provides hardware-specific implementations of core functions.
The document discusses the Linux kernel and its structure. The Linux kernel acts as the interface between hardware and software, contains device drivers for peripherals, handles resource allocation and tracking application access to files. It is also responsible for security and access controls for users. The kernel version numbers use even numbers to indicate stable releases.
The document provides an overview of the Linux kernel architecture. It discusses that the kernel includes modules/subsystems that provide operating system functions and forms the core of the OS. It describes the kernel's user space and kernel space, with user processes running in user space and kernel processes running in kernel space. System calls are used to pass arguments between the spaces. The document also summarizes several key kernel functions, including the file system, process management, device drivers, memory management, and networking.
The Linux Kernel Implementation of Pipes and FIFOsDivye Kapoor
A walkthrough of the code structure used in the linux kernel to implement pipes and FIFOs.
This was presented to a Senior level class at the Indian Institute of Technology, Roorkee.
This document discusses kernel modules in Linux. It begins by defining the kernel as the central part of the operating system that manages processes, memory, devices, and storage. Kernel modules allow new functionality to be added to the kernel at runtime without rebooting. Common module commands like insmod, lsmod and rmmod are described. The document outlines how modules are loaded and unloaded by the kernel and provides a simple "hello world" example of a kernel module.
Linux device drivers act as an interface between hardware devices and user programs. They communicate with hardware devices and expose an interface to user applications through system calls. Device drivers can be loaded as kernel modules and provide access to devices through special files in the /dev directory. Common operations for drivers include handling read and write requests either through interrupt-driven or polling-based I/O.
This presentation gives introduction to kernel module programming with sample kernel module.
It helps to start with kernel programming and how it can be used to develop various types of device drivers.
Quontra Solutions offers Job oriented Linux online training with updated technologies. For more info about our Linux online training contact us directly. We are providing Linux online training to all students throughout worldwide by real time faculties. Our Linux training strengthens your skills and knowledge which will helps you to gain a competitive advantage in starting your career. Outclasses will help you to gain knowledge on real time scenario. It will be most use full to boost up your career.
Our training sessions are designed in such a way that all the students can be convenient with the training schedules and course timings.
Along with Training, we also conduct several mock interviews along with Job Placement Assistance. Attend Free Demo before joining the class.
Our Features:
• Real world projects to get practical based experience
• Online tests to explore the resource learning
• Experienced certified trainers as instructors
• One to one personalized training with desktop access
• Case studies and state of art library to access study material
• Resume build assistance to win in interviews
Contact us:
Simson Andrew
Email: info@quontrasolutions.com
web: www.quontrasolutions.com
This document outlines the key components of a Linux character device driver, including modules, major and minor numbers, data structures like struct file and struct file_operations, driver registration, and core functions like open, release, read and write. It provides an introduction to character device drivers in Linux and their basic architecture.
This presentation gives an overview of Linux kernel block I/O susbsystem functionality, importance of I/O schedulers in Block layer. It also describes the different types of I/O Schedulers including the Deadline I/O scheduler, Anticipatory I/O Scheduler, Complete Fair queuing I/O scheduler and Noop I/O scheduler.
Some basic knowledges required for beginners in writing linux kernel module - with a description of linux source tree, so that the idea of where and how develops. The working of insmod and rmmod commands are described also.
This document provides an overview of the Linux architecture. It describes Linux as a free UNIX-like kernel that forms the GNU/Linux operating system together with the GNU project software. The kernel acts as an intermediary between hardware and software, managing processes, scheduling, and resources. Processes can be in different states like running, waiting, or sleeping. The kernel uses preemptive multitasking to switch between processes and prioritize interrupts. System calls allow processes to be created and managed.
This document provides an introduction to the Linux kernel, including its main features and architecture. It discusses the kernel's portable, open source, multi-user nature and hierarchical file system. The document outlines the Linux versioning scheme and describes the kernel's main subsystems, including process management, memory management, the virtual file system, network stack, and system call interface. It explains how the kernel uses virtual memory to separate user space and privileged kernel space.
This document provides an introduction to Linux device drivers. It discusses that device drivers provide an abstraction layer between software and hardware, hiding hardware details. It describes different types of devices like character and block devices. It covers key concepts like loadable modules, driver entry/exit points, interrupts, deferred work, and memory-mapped peripherals. The document uses serial/UART drivers and the TTY layer as examples to illustrate driver concepts.
There are three ARM core variants for memory models:
- Flat memory model provides direct access to all memory but is not suitable for multi-tasking. Examples are ARM7TDMI and ARM7EJ-S.
- Memory Protection Unit (MPU) uses regions of memory to actively protect system resources for multi-tasking platforms. Examples are ARM946E-S.
- Memory Management Unit (MMU) provides protection of resources and enables virtual memory. The ARM1026EJ-S uses an MMU.
The document provides an introduction to Linux kernel modules. It discusses that kernel modules extend the capabilities of the Linux kernel by executing code as part of the kernel. It then describes the anatomy of a kernel module, including initialization and cleanup functions. The document demonstrates a simple "hello world" kernel module example and how to build, load and unload kernel modules. It also introduces the idea of character device drivers as a more advanced kernel module example.
The document provides an overview of the initialization phase of the Linux kernel. It discusses how the kernel enables paging to transition from physical to virtual memory addresses. It then describes the various initialization functions that are called by start_kernel to initialize kernel features and architecture-specific code. Some key initialization tasks discussed include creating an identity page table, clearing BSS, and reserving BIOS memory.
The document discusses Linux device drivers, including how they interface between user programs and hardware using a file interface, are implemented as loadable kernel modules (LKMs) that are inserted into the kernel, and how common operations like open, read, write, and release are mapped to kernel functions through a file operations structure.
The document is a presentation by Vivek Kurmi about the Linux Install Fest-2012 event on October 16th, 2012. It provides an introduction to Linux, discussing that it is free and open source, runs on multiple hardware platforms, and has many flavors due to its open source nature. It covers the history of Linux from UNIX to GNU to Linux's creation in 1991. It also highlights advantages of Linux and examples of organizations that use Linux.
Overview of the Linux Kernel, based on "Anatomy of the Linux Kernel" by M. Tim Jones, (IBM Developerworks) http://www.ibm.com/developerworks/linux/library/l-linux-kernel/
Kernel Recipes 2015: Kernel packet capture technologiesAnne Nicolas
Sniffing through the ages
Capturing packets running on the wire to send them to a software doing analysis seems at first sight a simple tasks. But one has not to forget that with current network this can means capturing 30M packets per second. The objective of this talk is to show what methods and techniques have been implemented in Linux and how they have evolved over time.
The talk will cover AF_PACKET capture as well as PF_RING, dpdk and netmap. It will try to show how the various evolution of hardware and software have had an impact on the design of these technologies. Regarding software a special focus will be made on Suricata IDS which is implementing most of these capture methods.
Eric Leblond, Stamus Networks
A hybrid kernel is a kernel architecture that combines aspects of microkernel and monolithic kernel architectures. It aims to have the modularity of a microkernel but is implemented similarly to a monolithic kernel, with nearly all operating system services running in kernel space rather than user space. The best known example is the Microsoft Windows NT kernel, which is classified as a hybrid kernel due to some subsystems running in user mode processes rather than purely in kernel mode. Another example is the XNU kernel used in macOS and iOS, which combines the Mach microkernel with BSD components.
The document discusses the Filesystem Hierarchy Standard (FHS) used in Red Hat Enterprise Linux. It describes the structure of the root directory and the purpose of each subdirectory, including: /bin for essential user binaries, /sbin for system administration binaries, /etc for configuration files, /dev for device files, /proc for process information, /var for variable and log files, /tmp for temporary files, /usr for secondary user programs, /home for user home directories, /boot for boot loader files, /lib for essential system libraries, /opt for optional third-party software, /mnt for mounting filesystems, and /media for mounting removable media.
Part 1 of 'Introduction to Linux for bioinformatics': IntroductionJoachim Jacob
This is part 1 of the training session 'Introduction to Linux for bioinformatics'. We explain in very general terms what Linux is and stands for, and how we can get access to it. Interested in following this training session? Please contact me at http://www.jakonix.be/contact.html
Linux is a widely used open source operating system kernel that is assembled under a free and open source software development model. It is modular and derives from Unix principles of the 1970s-1980s. Popular Linux distributions like Ubuntu package the Linux kernel along with utilities, libraries and application software. Linux can run on diverse computer architectures and includes graphical user interfaces like GNOME and KDE. It is typically free, reliable and secure compared to Windows but has fewer software options. Overall, Linux and Windows both have advantages and differences that allow IT managers to choose the best operating system for their organization's needs.
SystemTap is a dynamic tracing tool for Linux systems. It allows users to easily gather information about the running Linux system by defining probe points in a script. The script is compiled into a kernel module which can then be loaded to monitor the specified probe points. Some examples of useful probe points include functions, system calls, and kernel statements. SystemTap scripts can be used to trace execution, profile performance, monitor kernel functions and debug problems by printing at probe points. It provides a safe way to observe a live system without needing to recompile the kernel.
"How Fuel Uses Puppet to Deploy OpenStack" -
Master or masterless, sequencing solutions, giant catalogs, getting in sync with upstream community manifests, and more - Christopher Aedo (from Mirantis) will talk about the lessons learned while building Fuel, the open source OpenStack deployment and management tool. (Slides from Portland Puppet Users Group meeting in March 2015)
The document discusses Platform as a Service (PaaS) and Cloud Foundry, an open source PaaS. Cloud Foundry allows developers to deploy and scale applications in seconds across clouds without vendor lock-in. It provides choice of development frameworks, deployment targets, and application services. Cloud Foundry has seen broad adoption due to its support for developer agility and portability across private and public clouds. It has also gained popularity through its open governance model and large, production-grade deployments.
This document provides an overview of the Linux operating system, including its history, design principles, and key components. It describes how Linux originated as a small kernel developed by Linus Torvalds in 1991 and has since grown through collaboration into a full-fledged open source operating system compatible with UNIX standards. The document outlines Linux's modular kernel architecture, use of kernel modules, process and memory management designs, and standards-compliance.
This document provides an overview of the Linux operating system, including its history and design principles. It describes key components like the Linux kernel, kernel modules, process management, scheduling, and memory management. It discusses how Linux implements features like file systems, input/output, and interprocess communication. The document also covers Linux distributions and licensing. It provides details on the evolution of the Linux kernel from early versions to version 2.0 and beyond, which added support for new architectures and multiprocessor systems.
The document discusses network programming with sockets. It outlines basic socket programming concepts like client-server models, TCP and UDP services, and BSD sockets. It then describes key socket functions for creation and setup, establishing connections, sending/receiving data, and tearing down connections.
Debugging linux kernel tools and techniquesSatpal Parmar
This document discusses tools and techniques for debugging the Linux kernel, including debuggers like gdb, built-in debugging facilities, system logs, and crash dump analysis tools like LKCD. It outlines common issues like kernel crashes and hangs, and provides an example of analyzing an "oops" crash dump to identify the failing line of code through tools like ksymoops. It also covers generating a full system memory dump using LKCD for thorough crash investigation.
Mirantis developed Fuel to automate OpenStack deployments. Fuel uses tools like Cobbler and Puppet to provision hardware and deploy OpenStack in an automated, error-proof manner. It supports various deployment topologies including single-node, multi-node non-HA, and multi-node HA. Fuel Web provides a web-based interface for managing OpenStack clusters deployed using Fuel.
The document discusses the history and development of Linux and Windows operating systems. It mentions that Linus Torvalds developed the initial Linux kernel version 0.0.1 in 1991 as an open source operating system. Microsoft developed Windows NT to support both OS/2 and POSIX APIs, though it later switched to the Win32 API. The document also compares advantages and disadvantages of Linux versus Windows, such as Linux being more stable and secure while Windows has a larger software selection.
This document provides an introduction to Linux, including its history and architecture. It describes Linux's origins from Unix in the 1960s and the development of the Linux kernel by Linus Torvalds in 1991. It outlines the key components of a Linux system, including the kernel, shell, file system, processes, networking, and desktop environments. It also discusses booting a Linux system and provides resources for learning more about Linux distributions and building your own operating system.
Troubleshooting Linux Kernel Modules And Device DriversSatpal Parmar
The document discusses various techniques for debugging Linux kernel modules and device drivers, including:
1) Using printk statements to output debug messages from kernel space.
2) Watching system calls with strace to debug interactions between user and kernel space.
3) Adding /proc file system entries and write functions to dynamically modify driver values at runtime.
4) Enabling source-level debugging with tools like kgdb to debug at the level of C source code.
Windows 2000 architecture has a layered design with a kernel mode and user mode. The kernel mode consists of the hardware abstraction layer, kernel, and executive services which have unrestricted system access. The user mode contains subsystems and has limited resource access. The kernel schedules processes and handles interrupts, synchronization, and recovery. Executive services provide common functions like I/O management, security, and power management through components like the object manager and process manager. Environment subsystems allow running applications from other operating systems by converting their API calls.
This document provides an overview of the Linux kernel internals and device drivers. It discusses topics like memory management, process creation, inter-process communication using shared memory, and device drivers. The key aspects covered are virtual memory mapping, demand paging, steps in program execution, different types of device drivers, and how the kernel interacts with hardware through device drivers in the userspace.
The document discusses Linux kernel internals and provides an overview of key concepts such as memory management, process creation, device drivers, and file systems. It describes how the kernel handles tasks like compiling programs, managing memory and processes, and facilitating communication between software and hardware. The document also outlines common Linux system calls and functions related to program execution.
Workshop - Linux Memory Analysis with VolatilityAndrew Case
Slides from my 3 hour workshop at Blackhat Vegas 2011. Covers using Volatility to perform Linux memory analysis investigations as well Linux kernel internals.
The document summarizes the architecture of the Linux operating system. It discusses that Linux is divided into the kernel space and user space. The kernel is responsible for process management, memory management, file systems, device drivers, and the network stack. It also touches on architecture-dependent code and the components of the Linux system like the kernel, user applications, and system libraries.
32-bit preemptive multitasking operating system for Intel microprocessors. Uses a micro-kernel architecture. Uses a micro-kernel architecture. Environmental subsystems emulate different operating systems. Protection subsystems provide security functions
This document summarizes key aspects of disk structure, disk scheduling, disk management, swap space management, and Windows 2000. It discusses how disks are logically structured and addressed, factors that impact disk access time like seek time and rotational latency. It covers disk formatting, partitioning, boot blocks, handling bad blocks. It explains how operating systems manage swap space, where it is located, and examples of swap space use. It provides an overview of Windows 2000, describing its design, components like the kernel, virtual memory manager, I/O manager, and environmental subsystems.
The document provides an overview of operating systems, including processes, threads, interprocess communication, deadlocks, and scheduling. It discusses the evolution of operating systems from first to fourth generation. Key concepts covered include processes, files, system calls, command interpreters, and signals. Operating system structures like monolithic, layered, and client-server models are summarized. Common interprocess communication problems like the bounded buffer, readers-writers, and dining philosophers problems are also briefly outlined. Finally, it discusses process scheduling algorithms, deadlock conditions and strategies to handle deadlocks.
This document provides an overview of embedded Linux for an embedded systems design course. It discusses various commercial and open source embedded Linux distributions and their characteristics. It also covers important topics for embedded Linux including tool chains, the Linux kernel, debugging, driver development, memory management, and synchronization techniques. Example code snippets are provided for common Linux system programming tasks like file I/O, processes, threads, IPC, signals, and sockets. Cross-compiling for embedded targets is also briefly explained.
Windows XP is a 32-bit, preemptive multitasking operating system that was the most widely used OS at the time. It has a layered architecture with a microkernel at its core providing basic services, and various user-mode subsystems that emulate other operating systems. Its design focuses on extensibility, portability, reliability, compatibility, and performance. It uses a file system called NTFS that supports advanced features like security and recovery through transaction logging.
This document summarizes key concepts related to I/O structure in operating systems, including disk structure, disk scheduling, disk management, and swap-space management. It discusses how disks are logically addressed and mapped to physical sectors. It also describes different disk scheduling algorithms like SSTF, SCAN, C-SCAN and factors that influence algorithm selection. The document outlines the processes involved in low-level formatting, logical formatting, and handling bad blocks. It concludes with an overview of swap-space management in various operating systems.
The document provides an overview of the Linux operating system, including:
- An introduction to Linux and its history as an open-source clone of UNIX.
- Descriptions of Linux's core functionality like multi-user support and virtual memory.
- Discussions of key Linux components like kernels, distributions, packages, and updates.
- Explanations of enterprise-level Linux features around performance, scalability, and reliability.
This document provides an overview of the Ubuntu operating system. It discusses Ubuntu's history as a Debian-based Linux distribution first released in 2004. It also covers Ubuntu's key features, components, and principles such as its use of the Linux kernel, GNOME desktop environment, and Ext4 file system. The document discusses Ubuntu's security, processes, memory management, networking, and compares its robustness to other operating systems. It provides examples of basic Ubuntu commands and how to password protect the GRUB boot loader for added security.
This document summarizes key aspects of the Linux kernel's memory management system, including:
1) It describes the virtual address space for a process, including user/kernel segments, virtual memory areas, and system calls like brk for dynamic memory allocation.
2) It explains the block device caching system using buffer lists to cache blocks in memory.
3) It outlines the page cache and management, including finding free pages and handling page faults.
Regarding About Operating System Structuresankarkvdc
The document discusses various operating system structures including monolithic, layered, microkernel, and hybrid structures. It provides examples of each type including UNIX/Linux as monolithic, Mach as microkernel, and macOS/iOS as hybrid using the Darwin kernel based on Mach microkernel and BSD UNIX kernel. The document also discusses building, booting, debugging, and performance tuning operating systems with examples for Linux.
The document discusses best practices for deploying MongoDB including sizing hardware with sufficient memory, CPU and I/O; using an appropriate operating system and filesystem; installing and upgrading MongoDB; ensuring durability with replication and backups; implementing security, monitoring performance with tools, and considerations for deploying on Amazon EC2.
Introduction to Linux Kernel by Quontra SolutionsQUONTRASOLUTIONS
Course Duration: 30-35 hours Training + Assignments + Actual Project Based Case Studies
Training Materials: All attendees will receive,
Assignment after each module, Video recording of every session
Notes and study material for examples covered.
Access to the Training Blog & Repository of Materials
Pre-requisites:
Basic Computer Skills and knowledge of IT.
Training Highlights
* Focus on Hands on training.
* 30 hours of Assignments, Live Case Studies.
* Video Recordings of sessions provided.
* One Problem Statement discussed across the whole training program.
* Resume prep, Interview Questions provided.
WEBSITE: www.QuontraSolutions.com
Contact Info: Phone +1 404-900-9988(or) Email - info@quontrasolutions.com
This document provides an overview of Linux internals and networking concepts covered in 3 sentences or less:
It introduces Linux internals topics like processes, memory management, and virtual file systems. It also discusses networking concepts and provides a brief history of operating systems development. The document contains various sections on Linux components, kernel subsystems, virtual file systems, and transitioning to systems programming.
Linux began in 1991 as a personal project by Finnish student Linus Torvalds to create a free operating system kernel. The Linux kernel forms the core of the operating system, providing functions to run processes and access hardware resources. The Linux system consists of the kernel, system libraries that define standard functions for applications to interact with the kernel, and system utilities for maintaining operating system abstractions. The kernel uses both segmentation and paging for memory management, dividing a process's address space into segments with different protection modes and paging small regions of addresses to physical memory.
This document describes a distributed compilation system called DistCom that utilizes idle computing resources across a network to speed up software build processes. It presents a distributed server/client model using object files as the basic unit. It also discusses CPU scheduling techniques for remote PC resources and cross-compiling for heterogeneous architectures. An evaluation shows DistCom can reduce a mobile platform build time by 65% compared to a local build, achieving performance similar to an 8-core PC using 10 distributed machines.
The Java Collection Framework provides interfaces and implementations for commonly used data structures like lists, sets, maps and queues. Some key interfaces include Collection, Set, List, Map and SortedSet. Common implementations are ArrayList, LinkedList, HashSet, TreeSet, HashMap and TreeMap. The framework also includes iterators for traversing collections and algorithms for sorting. Generic types were introduced in Java 5 for type-safe collections.
The document discusses the C programming language. It notes that C is commonly used for embedded systems as it produces efficient code and is portable across processors. The history of C is described, including its origins in the late 1960s/early 1970s at Bell Labs as a system programming language derived from B and BCPL. Examples of Hello World and Euclid's algorithm in C are provided to illustrate basic C syntax and constructs. Key aspects of C like types, expressions, functions, and memory management are summarized.
This document provides an overview of Unit 1 and Unit 2 of the B.Tech II Yr II Semester course. Unit 1 covers object-oriented programming concepts like classes, inheritance, polymorphism over 5 lectures. The slides cover topics such as the need for OOP, classes and instances, method binding and exceptions. Unit 2 covers Java fundamentals like data types, variables, control statements and classes over 7 lectures across 85 slides, including the history of Java and its evolution from C and C++.
This document discusses Java threads and multithreading. It begins by defining multitasking as allowing multiple programs to run concurrently, while multithreading refers to multiple threads of control within a single program. It notes that threads allow maintaining responsiveness during long tasks and enabling cancellation of separable tasks. The document then covers creating and managing threads in Java by extending the Thread class or implementing Runnable, and describes thread states, priorities, and daemon threads.
This document discusses sorting algorithms. It begins by defining sorting as arranging items in a sequence. It notes that 25-50% of computing power is used for sorting activities. Common sorting applications include organizing lists of student data, test scores, and race results. Sorting methods described include selection sort, bubble sort, shell sort, and quick sort. Selection sort works by repeatedly finding the largest element and swapping it into the sorted portion of the array. Bubble sort compares adjacent elements and swaps them if out of order, pushing larger elements towards the end over multiple passes. Pseudocode and C++ code examples are provided to demonstrate how selection and bubble sort algorithms work on integer and string arrays.
An applet is a Java program that runs within a web browser. Applets are embedded in HTML pages and run in a sandbox that prevents them from accessing the local computer's file system for security reasons. When writing an applet, you extend the JApplet class and override certain methods like init(), start(), stop(), destroy(), and paint() that are called at different points in the applet's lifecycle by the browser. The paint() method is used for any drawing or graphics output from the applet.
Packages in Java enable grouping of related classes and avoid namespace collisions. Package names use dot notation to represent directory structure. The fully qualified name of a class includes its package. To create a package, the directory structure must match the package name hierarchy. A class belongs to a package by including the package statement at the top of its file and storing the class in the corresponding directory. Packages must be imported or the CLASSPATH set to locate non-default packages.
This document provides an introduction to the CS-2303 System Programming Concepts course. It outlines the course objectives which include learning to program in C and C++, gaining experience with data structures and their low-level implementation in C, and learning object-oriented programming concepts. It describes the course structure, assignments, exams, and grading. It also provides background on C and its role as a systems programming language, and a brief history of programming language development leading up to C.
The document discusses binary trees and their properties. It defines binary trees and provides terminology used to describe them, such as nodes, levels, paths, and heights. It describes different types of binary trees like complete, full, and binary search trees. It discusses common traversal methods for binary trees like breadth-first and depth-first. It also covers insertion and deletion of nodes in binary trees, describing approaches like merging subtrees and copying values.
Applets allow Java programs to be run within web browsers. An applet is a Java class that extends Applet and overrides certain methods like init(), start(), stop(), and paint(). These methods control the applet's lifecycle and graphics rendering. Applets are subject to security restrictions like not being able to access the local file system. They can be embedded in HTML pages using special tags and retrieve configuration parameters from <param> tags.
The document discusses the C programming language. It notes that C is commonly used for embedded systems as it produces efficient code and is portable across processors. The history of C is described, including its origins in the late 1960s/early 1970s at Bell Labs as a system programming language derived from B and BCPL. Examples of Hello World and Euclid's algorithm in C are provided to illustrate basic C syntax and constructs. Key aspects of C like types, expressions, functions, and memory management are summarized.
This document discusses abstract classes and interfaces in Java. It explains that abstract classes can contain abstract methods that subclasses must implement. Interfaces also declare methods but do not define them, requiring implementing classes to provide the method definitions. The document provides examples of abstract classes and interfaces, and how they allow for generalized functionality across multiple classes through inheritance and implementation. It also discusses adapter classes that provide empty method bodies to partially implement interfaces.
This document provides an overview of exception handling in Java. It defines what exceptions are, common causes of exceptions, and how exception handling works in Java using keywords like try, catch, throw, throws, and finally. It also discusses different exception types, creating custom exceptions, and key classes related to exceptions in the java.util package like Date, TimeZone, Calendar, and GregorianCalendar.
Inheritance allows one class to acquire properties of another class. A subclass inherits all properties of its superclass and can add its own unique properties. When a method in a subclass has the same name and signature as a method in its superclass, it overrides that method. Dynamic method dispatch determines which version of an overridden method to call based on the actual object type at runtime rather than the reference variable type. Superclass constructors can be called from subclasses using the super keyword, and super can also be used to access hidden superclass members from subclasses.
This document discusses shared memory in Linux, including creating shared memory segments using shmget, attaching and detaching shared memory using shmat and shmdt, controlling shared memory segments using shmctl, and using mmap to map files to shared memory. It provides details on the system calls used for shared memory and examples of creating and using shared memory between processes.
1. Inheritance allows classes to reuse properties of existing classes by extending them, making the extended class a subclass and the original class the superclass.
2. A subclass inherits and can access all public and protected properties of its superclass but can also define its own properties.
3. The subclass constructor must call the superclass constructor either implicitly or explicitly using the super() method.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
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Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
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Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
5. Features
• Free
• Open system
• Open source
• GNU GPL (General Public License)
• POSIX standard
• High portability
• High performance
• Robust
• Large development toolset
• Large number of device drivers
• Large number of application programs
6. Features (Cont.)
• Multi-tasking
• Multi-user
• Multi-processing
• Virtual memory
• Monolithic kernel
• Loadable kernel modules
• Networking
• Shared libraries
• Support different file systems
• Support different executable file formats
• Support different networking protocols
• Support different architectures
13. Analysis of Linux Kernel Architecture
• Stability
• Safety
• Speed
• Brevity
• Compatability
• Portability
• Reusability and modifiability
• Monolithic kernel vs. microkernel
• Linux takes the advantages of monolithic kernel
and microkernel
16. Resources for Tracing Linux
• Source code browser
– cscope
– Global
– LXR (Source code navigator)
• Books
– Understanding the Linux Kernel, D. P. Bovet and M.
Cesati, O'Reilly & Associates, 2000.
– Linux Core Kernel – Commentary, In-Depth Code
Annotation, S. Maxwell, Coriolis Open Press, 1999.
– The Linux Kernel, Version 0.8-3, D. A Rusling, 1998.
– Linux Kernel Internals, 2nd
edition, M. Beck et al., Addison-
Wesley, 1998.
– Linux Kernel, R. Card et al., John Wiley & Sons, 1998.
17. How to compile Linux Kernel
1. make config (make manuconfig)
2. make depend
3. make boot
generate a compressed bootable linux kernel
arch/i386/boot/zIamge
make zdisk
generate kernel and write to disk
dd if=zImage of=/dev/fd0
make zlilo
generate kernel and copy to /vmlinuz
lilo: Linux Loader
19. Linux Kernel Components
• Bootstrap and system initializaiton
• Memory management
• Process management
• Interprocess communication
• File system
• Networking
• Device control and device drivers
20. Bootstrap and System Initialization
Events From Power-On To Linux
Kernel Running
21. Bootstrap and System Initialization
• Booting the PC (Events From Power On)
– Perform POST procedure
– Select boot device
– Load bootstrap program (bootsect.S) from floppy or HD
• Bootstrap program
– Hardware Initialization (setup.S)
– loads Linux kernel into memory (head.S)
– Initializes the Linux kernel
– Turn bootstrap sequence to start the first init process
22. Bootstrap and System Initialization (Cont.)
• Init process
– Create various system daemons
– Initialize kernel data structures
– Free initial memory unused afterwards
– Runs shell
• Shell accepts and executes user commands
25. Memory Management Subsystem
• Provides virtual memory mechanism
– Overcome memory limitation
– Makes the system appear to have more memory than it
actually has by sharing it between competing processes
as they need it.
• It provides:
– Large address spaces
– Protection
– Memory mapping
– Fair physical memory allocation
– Shared virtual memory
30. Abstract model of Virtual to Physical
address mapping
VPFN7
VPFN6
VPFN3
VPFN2
VPFN1
VPFN0
VPFN4
VPFN5
VPFN7
VPFN6
VPFN3
VPFN2
VPFN1
VPFN0
VPFN4
VPFN5
PFN3
PFN2
PFN1
PFN0
PFN4
Process X Process Y
Process X
Page Table
Process Y
Page Table
Virtual Memory Virtual Memory
Physical Memory
31. An Abstract Model of VM (Cont.)
• Each page table entry contains:
– Valid flag
– Physical page frame number
– Access control information
• X86 page table entry and page directory entry:
31 12 6 5 2 1 0
Page Address D A
U
/
S
R
/
W
P
32. Demand Paging
• Loading virtual pages into memory as they
are accessed
• Page fault handling
– faulting virtual address is invalid
– faulting virtual address was valid but the page
is not currently in memory
33. Swapping
• If a process needs to bring a virtual page
into physical memory and there are no free
physical pages available:
• Linux uses a Least Recently Used page
aging technique to choose pages which
might be removed from the system.
• Kernel Swap Daemon (kswapd)
34. Caches
• To improve performance, Linux uses a
number of memory management related
caches:
– Buffer Cache
– Page Caches
– Swap Cache
– Hardware Caches (Translation Look-aside
Buffers)
35. Page Allocation and Deallocation
• Linux uses the Buddy algorithm to effectively
allocate and deallocate blocks of pages.
• Pages are allocated in blocks which are powers of 2
in size.
– If the block of pages found is larger than requested must
be broken down until there is a block of the right size.
• The page deallocation codes recombine pages into
large blocks of free pages whenever it can.
– Whenever a block of pages is freed, the adjacent or buddy
block of the same size is checked to see if it is free.
39. What is a Process ?
• A program in execution.
• A process includes program's instructions and
data, program counter and all CPU's registers,
process stacks containing temporary data.
• Each individual process runs in its own virtual
address space and is not capable of interacting
with another process except through secure, kernel
managed mechanisms.
40. Linux Processes
• Each process is represented by a task_struct data
structure, containing:
– Process State
– Scheduling Information
– Identifiers
– Inter-Process Communication
– Times and Timers
– File system
– Virtual memory
– Processor Specific Context
44. Scheduling
• As well as the normal type of process, Linux supports
real time processes. The scheduler treats real time
processes differently from normal user processes
• Pre-emptive scheduling.
• Priority based scheduling algorithm
• Time-slice: 200ms
• Schedule: select the most deserving process to run
– Priority: weight
• Normal : counter
• Real Time : counter + 1000
46. Virtual Memory
• A process's virtual memory contains executable
code and data from many sources.
• Processes can allocate (virtual) memory to use
during their processing
• Demand paging is used where the virtual
memory of a process is brought into physical
memory only when a process attempts to use it.
49. Process Creation and Execution
• UNX process management separates the
creation of processes and the running of a
new program into two distinct operations.
– The fork system call creates a new process.
– A new program is run after a call to execve.
50. • Programs and commands are normally executed
by a command interpreter.
• A command interpreter is a user process like any
other process and is called a shell
ex.sh, bash and tcsh
• Executable object files:
– Contain executable code and data together with
information to be loaded and executed by OS
• Linux Binary Format
– ELF, a.out, script
Executing Programs
51. How to execute a program?
Shell clone itself and binary image is replaced with
executable image
Command enter
Search file in
process’s search path(PATH)
52. ELF
• ELF (Executable and Linkable Format)
object file format
– designed by Unix System Laboratories
– the most commonly used
format in Linux
Format header
Physical header
(Code)
Physical header
(Data)
Code
Data
54. Signals
• Signals inform processes of the occurrence of
asynchronous events.
• Processes may send each other signals by kill system
call, or kernel may send signals to a process.
• A set of defined signals in the system:
• 1)SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL
• 5) SIGTRAP 6) SIGIOT 7) SIGBUS 8) SIGFPE
• 9) SIGKILL 10) SIGUSR1 11) SIGSEGV 12) SIGUSR2
• 13) SIGPIPE 14) SIGALR 15)SIGTERM
• 17) SIGCHLD 18) SIGCONT 19) SIGSTOP 20) SIGTSTP
• 21) SIGTTIN 22) SIGTTOU 23) SIGURG 24) SIGXCPU
• 25) SIGXFSZ 26) SIGVTALRM 27) SIGPROF 28) SIGWINCH
• 29) SIGIO 30) SIGPWR
55. Signals (Cont.)
• A process can choose to block or handle signals itself
or allow kernel to handle it
• Kernel handles signals using default actions.
– E.g., SIGFPE(floating point exception) : core dump and exit
• Signal related fields in task_struct data structure
– signal (32 bits): pending signals
– blocked: a mask of blocked signal
– sigaction array: address of handling routine or a flag to let
kernel handle the signal
56. Pipes
• one-way flow of data
• The writer and the reader communicate
using standard read/write library function
TaskA TaskB
Communicationpipe
57. Restriction of Pipes and Signals
• Pipe:
– Impossible for any arbitrary process to read or write in a
pipe unless it is the child of the process which created it.
– Named Pipes (also known as FIFO)
• also one-way flow of data
• allowing unrelated processes to access a single FIFO.
• Signal
– The only information transported is a simple number,
which renders signals unsuitable for transferring data.
58. System V IPC Mechanism
• Linux supports 3 types of IPC mechanisms:
– Message queues, semaphores and shared
memory
– First appeared in UNIX System V in 1983
• They allow unrelated processes to
communicate with each other.
59. Key Management
• Processes may access these IPC resources
only by passing a unique reference
identifier to the kernel via system calls.
• Senders and receivers must agree on a
common key to find the reference identifier
for the System V IPC object.
• Access to these System V IPC objects is
checked using access permissions.
60. Shared Memory and Semaphores
• Shared memory
– Allow processes to communicate via memory that
appears in all of their virtual address space
– As with all System V IPC objects, access to shared
memory areas is controlled via keys and access rights
checking.
– Must rely on other mechanisms (e.g. semaphores) to
synchronize access to the memory
• Semaphores
– A semaphore is a location in memory whose value can
be tested and set (atomic) by more than one processes
– Can be used to implement critical regions
61. Create
Segment
Give a valid
IPC identifier
Process to attach
segment
For read and
write
Execute commands
about
Shared memory
Remove or
detach
segment
Sys_shmget() Sys_shmat()
Sys_shmctl()Sys_shmdt()
63. Message Queues
• Allow one or more processes to write messages,
which will be read by one or more reading
processes structmsqid_ds
structmsgs
IPC_NOID
IPC_UNUSED
65. Linux File System
• Linux supports different file system structures at
the same time
– Ext2, ISO 9660, ufs, FAT-16,VFAT,…
• Hierarchical File System Structure
– Linux adds each new file system into this single file
system tree as it is mounted.
• The real file systems are separated from the OS by
an interface layer: Virtual File System: VFS
• VFS allows Linux to support many different file
systems, each presenting a common software
interface to the VFS.
67. Mounting of Filesystems
/
bin dev etc lib sbin usr
bin include lib man sbin
bin include lib man sbin
/
bin dev etc lib sbin usr
/
mountingoperation
/usrfilesystemrootfilesystem
completehierarchyaftermounting/usr
68. The Layers in the File System
Process
1
Process
2
Process
n
VirtualFileSystem
ext2 msdos minix proc
Buffercache
Devicedrivers
Filesystem
Usermode
Systemmode
69. Ext2 File System
• Devised (by Rémy Card) as an extensible and
powerful file system for Linux.
• Allocation space to files
– Data in files is kept in fixed-size data blocks
– Indexed allocation (inode)
• directory : special file which contains pointers to
the inodes of its directory entries
• Divides the logical partition that it occupies into
Block Groups.
70. Physical Layout of File Systems
Block
Group 0
Block
Group 1
…...
Block
Group n
Super
block
Group
descriptors
Block
bitmap
Inode
bitmap
Inode
table
Data
blocks
• Schematic Structure of a UNIX File System
• Physical Layout of EXT2 File System
Inodeblocks
2...
SuperblockBootblock
10
Datablocks
71. The EXT2 Inode
Mode
Owner Info
Size
Timestamps
Direct Blocks
Indirect blocks
Double Indirect
Triple Indirect
data
data
data
data
data
data
data
73. The Virtual File System (VFS)
System callinterface
Virtualfilesystem
ext2fsminix proc
Buffercache
Devicedrivers
Tasks
Machine
Inode
cache
Directory
cache
74. Allocating Blocks to a File
• To avoid fragmentation that file blocks may
spread all over the file system, EXT2 file
system:
– Allocating the new blocks for a file physically
close to its current data blocks or at least in the
same Block Group as its current data blocks as
possible.
– Block preallocation
75. Speedup Access
• VFS Inode Cache
• Directory Cache
– stores the mapping between the full directory names
and their inode numbers.
• Buffer Cache
– All of the Linux file systems use a common buffer
cache to cache data buffers from the underlying devices
• Replacement policy: LRU
76. bdflush & update Kernel Daemons
• The bdflush kernel daemon
– provides a dynamic response to the system
having too many dirty buffers (default:60%).
– tries to write a reasonable number of dirty
buffers out to their owning disks (default:500).
• The update daemon
– periodically flush all older dirty buffers out to
disk
77. The /proc File System
• It does not really exist.
• Presents a user readable windows into the kernel’s
inner workings.
• The /proc file system serves information about the running
system. It not only allows access to process data but also
allows you to request the kernel status by reading files in the
hierarchy.
• System information
– Process-Specific Subdirectories
– Kernel data
– IDE devices in /proc/ide
– Networking info in /proc/net, SCSI info
– Parallel port info in /proc/parport
– TTY info in /proc/tty
82. Linux BSD Socket Data Structure
files_struct
count
close_on_exec
open_fs
fd[0]
fd[1]
fd[255]
file
f_mode
f_pos
f_flags
f_count
f_owner
f_op
f_inode
f_version
inode
sock
socket
type
protocol
data
type
protocol
socket
SOCK_STREAM
SOCK_STREAM
Address Family
socket operations
BSD Socket
File Operations
lseek
read
write
select
ioctl
close
fasync
83. Loadable Kernel Module
• A Kernel Module is not an independent
executable, but an object file which will be
linked into the kernel in runtime.
• Modules can be “dynamically integrated”
into the kernel. When no longer used, the
modules may then be unloaded.
• Enable the system to have an “extended”
kernel.