Building Embedded Linux Systems Free

FREE BUILDING EMBEDDED LINUX SYSTEMS PDF

Jump to navigation. Linux is being deployed into a much wider array of devices than Linus Torvalds anticipated when he was working on it in his dorm room. The variety of supported chip architectures is astounding and has led to Linux in devices large and small; from huge IBM mainframes to tiny devices no bigger than their connection ports and everything in between. It is used in large enterprise data centers, internet infrastructure devices, Building Embedded Linux Systems personal development systems. It also powers consumer electronics, mobile phones, and many Internet of Things devices. When building Linux software for desktop and enterprise-class devices, developers Building Embedded Linux Systems use a desktop distribution such as Ubuntu on their build machines to have an environment as close as possible to the one where the software will be deployed. Tools such as VirtualBox and Docker allow even better alignment between development, testing, and productions environments. Wikipedia defines an embedded system as: "A computer system with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints. I find it simple enough to say that an embedded system is a computer that most people don't think of as a computer. Its primary role is to serve as an appliance of Building Embedded Linux Systems sort, and it is not considered a general-purpose computing platform. They may use different chip architectures, software stacks, and even operating systems. Development workflows are very different for embedded developers vs. Typically, the build output will consist of an Building Embedded Linux Systems software image for the target device, including the kernel, device drivers, libraries, and application software and sometimes the bootloader. In this article, I will present a survey of four commonly available options for building embedded Linux systems. I won't teach you Building Embedded Linux Systems to use any of them; there are plenty of in-depth online learning resources once you have narrowed your choices. No option is right for all use cases, and I hope to present enough details to direct your decision. Full disclosure: most of my work in embedded Linux has focused on the Yocto project, and my knowledge and bias to this system will Building Embedded Linux Systems be evident. Yocto uses Openembedded as its build system. Technically the two are separate projects; in practice, however, users do not need to understand the distinction, and the project names are frequently used interchangeably. The Yocto project is widely used in the industry and has backing from many influential companies. Additionally, it has a large and vibrant developer community and ecosystem contributing to it. There are many options for getting support with Building Embedded Linux Systems. There are books and other training materials if you wish to do-it-yourself. Many engineers with experience in Yocto are available if you Building Embedded Linux Systems to hire expertise. And many commercial organizations provide turnkey Yocto-based products or services-based implementation and customization for your design. The Yocto project is easily expanded through layerswhich can be published independently to add additional functionality, to target platforms not available in the project releases, or to store customizations unique to your system. Layers can be added to your configuration to add unique features that are not specifically included in the stock releases; for example, the " meta- browser " layer contains recipes for web browsers, which can be easily Building Embedded Linux Systems for your system. Because they are independently maintained, layers can be on a different release schedule tuned to the layers' development velocity than the standard Yocto releases. Yocto has arguably the widest device support of any of the options discussed in this article. Due to support from many semiconductor and board manufacturers, it's likely Yocto will support any target platform you choose. Finally, Yocto is extremely flexible and customizable. Customizations for your specific application can be stored in a layer for encapsulation and isolation. Customizations unique to a feature layer are generally stored as part of the layer itself, which allows the same settings to be applied simultaneously to multiple system configurations. Yocto also provides a well-defined layer priority and override capability. This allows you to define the order in which layers are applied and searched for metadata. It also enables you to override settings in layers with higher priority; for instance, many customizations to existing recipes will be added in your private layers, with the order precisely controlled by the priorities. The biggest disadvantage with the Yocto project is the learning curve. It takes significant time and effort to learn the system and truly understand it. Depending on your needs, this may be too large of an investment in technologies and competence that are not central to your Building Embedded Linux Systems. In such cases, working with one of the commercial vendors may be a good option. Development build times and resources are fairly high for Yocto project builds. The number of packages that need to be built, including the toolchain, kernel, and all target runtime components, is significant. Development workstations for Yocto developers tend to be large systems. Using a compact notebook is not recommended. This can be mitigated by using cloud-based build servers available from many providers. Additionally, Yocto has a built-in caching mechanism that allows it to reuse previously built components when it determines that the parameters for building a particular package have not changed. Using the Yocto project for your next embedded Linux design is a strong choice. Of the options presented here, it is the most broadly applicable regardless of your target use case. The broad industry support, active community, and wide platform support make this a good choice for must designers. The Buildroot project is Building Embedded Linux Systems as "a simple, efficient, and easy-to-use tool to generate embedded Linux systems through cross-compilation. In general, Buildroot will disable all optional compile-time settings for all packages with a few notable exceptionsresulting in the smallest possible system. It will be up to the system designer to enable the settings that are appropriate for a given device. Buildroot builds all components from source but does not support on-target package management. As such, it is sometimes called a firmware generator since the images are largely fixed at build time. Applications can update the target filesystem, but there is no mechanism to install new packages into a running system. Buildroot's focus on simplicity means that, in general, it is easier to learn than Yocto. The core build system is written in Make and is short enough to allow a developer to understand the entire system while being expandable enough to meet the needs of embedded Linux developers. The Buildroot core generally only handles common use cases, but it is expandable via scripting. The Buildroot system uses normal Makefiles and the Kconfig language for its configuration. Kconfig was developed by the Linux kernel community and is widely used in open source projects, making it familiar to many developers. Due to the design goal of disabling all optional build-time settings, Buildroot will generally produce the smallest possible images using the out-of-the-box configuration. The build times Building Embedded Linux Systems build host resources will likewise be smaller, in general, than those of the Yocto project. The focus on simplicity and minimal enabled build options imply that you may need to do significant customization to configure a Buildroot build for your application. Additionally, all configuration options are stored in a single file, which means if you have multiple hardware platforms, you will need to make each of your customization changes for each platform. Any change to the system configuration file requires a full rebuild of all packages. This is somewhat mitigated by the minimal image sizes and build times compared with Yocto, but it can result in long builds while you are tweaking your configuration. Intermediate package state caching is not enabled by default and is not as thorough as the Yocto implementation. This means that, while the first build may be shorter than an equivalent Yocto build, subsequent builds may require rebuilding of many components. Using Buildroot for your next embedded Linux design is a good choice for most applications. If your design requires multiple hardware types or other differences, you may want to reconsider due to the complexity of synchronizing multiple configurations, however, for a system consisting of a single setup, Buildroot will likely work well for you. The OpenWRT project was started to develop custom firmware for consumer routers. Many of the low-cost routers available at your local retailer are capable of running a Linux system, but maybe not out of Building Embedded Linux Systems box. The OpenWRT project produces updated firmware images for many devices that have been abandoned by their manufacturers and gives these devices a new lease on life. The OpenWRT project's primary deliverables are binary images for a large number of commercial devices. There are network-accessible package repositories that allow device end users to add new software Building Embedded Linux Systems their systems. The OpenWRT build system is a general-purpose build system, which allows developers to create custom versions to meet their own requirements and add new packages, but its primary focus is target binaries. If you are looking for replacement firmware for a commercial device, OpenWRT should be on Building Embedded Linux Systems list of options. It is Building Embedded Linux Systems and may protect you from issues that the manufacturer's Building Embedded Linux Systems cannot. You can add extra functionality as well, making your devices more useful. If your embedded design is networking-focused, OpenWRT is a good choice. Networking applications are the primary use case for OpenWRT, and you will likely find many of those software packages available in it. OpenWRT imposes significant policy decisions on your design vs. Yocto and Buildroot. If these decisions don't meet your design goals, you may have to do non-trivial modifications. Allowing package-based updates in a fleet of deployed devices is difficult to manage. This, by definition, results in a different software load than what your QA team tested. Additionally, it is difficult to guarantee atomic installs with most package managers, and an ill-timed power cycle can leave your device in an unpredictable state. OpenWRT is a good choice for hobbyist projects or for reusing commercial hardware. It is also Building Embedded Linux Systems good choice for networking applications. If you need significant customization from the default setup, you may prefer Buildroot or Yocto. A common approach to designing embedded Linux systems is to start with a desktop distribution, such as Debian or Red Hatand remove unneeded components until the installed image fits into the footprint of your target device. This is Building Embedded Linux Systems approach taken for the popular Raspbian distribution for the Raspberry Pi platform. The primary advantage of this approach is familiarity. Often, embedded Linux developers are also desktop Linux users and are well-versed in their distro of choice. Using a similar environment on the target may allow developers to get started more quickly. Depending on Building Embedded Linux Systems chosen distribution, many additional tools can be installed using standard packaging tools such as apt and yum. It may be possible to attach a display and keyboard to your target device and do all your development directly there. For developers new to the embedded space, this is likely to be a more familiar environment and removes the need to configure and use a tricky cross-development setup. The number of packages available for most desktop distributions is generally greater than that available for the embedded-specific builders discussed previously. Building Embedded Linux Systems, 2nd Edition [Book] Linux Building Embedded Linux Systems first released into an unsuspecting world in the summer of Initially the spare-time hobby of a Finnish computer scientist by the name of Linus Torvalds, Linux was at first accessible only in software source code form to those with enough expertise to Building Embedded Linux Systems and install it. Early enthusiasts most also developers Building Embedded Linux Systems by necessity exploited the growth of the Internet in the early s as a means to build online communities and drive development forward. These communities helped to build the first Linux software distributions, containing all the software components needed to install and use a Linux system without requiring users to be technical experts. Over the next decade, Linux grew into the mature Unix-like operating system it is today. Linux now powers anything and everything from the smallest handheld gadget to the largest supercomputing cluster, and a nearly infinite range of different devices in between. In addition, a growing number of multinational corporations have successfully built businesses selling Linux software. In many ways, Linux came along at the right moment in time. But it owes a lot of its success to the work of projects that came before it. Without the hard work of Richard Stallman and the Free Software Foundation FSF over the decade prior to Linux arriving on the scene, many of the tools needed to actually build and use a Linux system would not exist. The FSF produced the GNU C Compiler GCC and many of the other tools and utilities necessary for building your own embedded Linux systems from scratch, or at least from pre-built collections of these tools that are supplied by third-party vendors. Embedded systems running Linux are the focus of this book. In many ways, these are even more ubiquitous than their workstation and server counterparts—mostly due to the sheer volume of Building Embedded Linux Systems and consumer gadgets that rely upon Linux for their operation. The embedded space is constantly growing with time. It includes obvious examples, such as cellular telephones, MP3 players, and a host of digital home entertainment devices, but also less-obvious examples, such as bank ATMs, printers, cars, traffic signals, medical equipment, technical diagnostic equipment, and many, many more. If you are reading this book, you probably have a basic idea why one would want to run an embedded system using Linux. Whether because of its flexibility, its robustness, its price tag, the community developing it, or the large number of vendors supporting it, there are many Building Embedded Linux Systems for choosing to build an embedded system with Linux and many ways to carry out the task. Building Embedded Linux Systems chapter provides the background for the material presented in the rest of the book by discussing definitions, real-life issues, generic embedded Linux systems architecture, and methodology. This chapter sets the stage for later chapters, which will build upon concepts introduced here. Sometimes, the designations may mean something very precise, whereas other times, a broad range or a category Building Embedded Linux Systems application is meant. Technically speaking, Linux refers only to an operating system kernel originally written by Linus Torvalds. The Linux kernel provides a variety of core system facilities required for any system based upon Linux to operate correctly. Application software relies upon specific features of the Linux kernel, such as its handling of hardware devices and its provision of a variety of fundamental abstractions, such as virtual memory, tasks known to users as Building Embedded Linux Systemssockets, files, and the like. The Linux kernel is typically started by a bootloader or system firmware, but once it is running, it is never Building Embedded Linux Systems down although the device itself might temporarily enter a low-powered suspended state. In large part, this is due to its growing popularity—people might not know what an operating system kernel is or does, but they will have perhaps heard of the term Linux. In fact, Linux is often used interchangeably in reference to the Linux kernel itself, a Linux system, or an entire prebuilt or source software distribution built upon the Linux kernel and related software. Such widely varying usage can lead to difficulties when providing technical explanations. Despite the confusion, as more people continue to hear of Linux, the trend is toward a generalization of the term as a reference to a complete system or distribution, running both GNU Building Embedded Linux Systems non-GNU software on a Linux kernel. If a friend mentions that her development team is using Linux, she probably means a complete system, not a kernel. When people use the term Linux Building Embedded Linux Systems everyday conversation, they usually are referring to a Linux distribution, such as those just mentioned. Linux distributions vary in purpose, size, and price, but they share Building Embedded Linux Systems common goal: to Building Embedded Linux Systems the user with a prepackaged, shrinkwrapped set of files and an installation procedure to get the kernel and various overlaid software installed on a certain type of hardware for a certain purpose. In the embedded space, a variety of embedded Linux distributions are available, such as those from MontaVista, Wind River, Timesys, Denx, and other specialist vendors. Embedded Linux typically refers to a complete system, or in the context of an embedded Linux vendor, to Building Embedded Linux Systems distribution targeted at embedded devices. Instead, the same Linux kernel source code is intended to be built for the widest range of devices, workstations, and servers imaginable, although obviously it is possible to configure a variety of optional features according to the intended use of the kernel. For example, it is unlikely that your embedded device will feature processors and terrabytes of memory, and so it is possible to configure out support for certain features typically found only on larger Linux systems. In the context of embedded development, you will typically encounter embedded Linux systems —devices that use the Linux kernel and a variety of other software—and embedded Linux distributions —a prepackaged set of applications tailored for embedded systems and Building Embedded Linux Systems tools to build a complete system. It is the latter that you are paying for when you go to an embedded Linux vendor. They provide development tools such as cross-compilers, debuggers, project management software, boot image builders, and so on. A growing number of vendors have chosen to integrate much of this functionality into customized plug-ins for their own versions of the community- developed Eclipse graphical IDE framework, which you will learn more about later in this book. Whether you use a vendor is entirely up to you— few of the examples mentioned in this book will make any assumption as to Building Embedded Linux Systems reliance or otherwise on a Linux vendor. In fact, much of this book is intended to equip you to build your own tools and tailored Linux distributions. This helps both those who want to use vendor supplied tools and those who do not. Understanding is key in either case, since greater understanding will help you to get more done faster. The bottom Building Embedded Linux Systems is, of Building Embedded Linux Systems, about time and resources. This kind of nomenclature should be familiar to anyone who has experience working with embedded systems. The original goal of the project was to provide a mechanism for deterministic response times under a Linux environment. RTLinux was sold to Wind River in early Today, there are Building Embedded Linux Systems other big name real-time projects for Linux, including one that is aiming to add real-time support to the official Linux kernel. Of course, by the time you read this book much of this technology may be even more commonplace than it is now, especially once real-time capabilities are available in every kind of Linux system installed from here to Timbuktu. What types of embedded systems are built with Linux? Why do people choose Linux? What issues are specific to the use of Linux in embedded systems? How many people actually use Linux in their embedded systems? How do they use it? All these questions and many more come to mind when pondering the use of Linux in an embedded system. Finding satisfactory answers to the fundamental questions is an important part of building the system. These answers will help you convince management, assist you in marketing your product, and most of all, enable you to evaluate whether your initial expectations have been met. We could use the traditional segments of embedded systems such as aerospace, automotive systems, consumer electronics, telecom, and so on to outline the types of embedded Linux systems, but this would provide no additional information in regard to the systems being designated, because embedded Linux systems may be similarly structured regardless of the market segment. Rather, let us instead classify embedded systems by Building Embedded Linux Systems criteria that will provide actual information about the structure of the system: size, time constraints, networkability, and degree of intended user interaction with the final system. The following sections cover each of these issues in more depth. The size of an embedded Linux system is determined by a number of different factors. First, there is physical size. Some systems can be fairly large, like the ones built out of clusters, whereas others are fairly small, like the Linux wristwatches that have been built in partnership with IBM. The physical size of an embedded system is often an important determination of the hardware capabilities of that system the size of the physical components inside the finished device and so secondly comes the size of the components Building Embedded Linux Systems the machine. These are very significant Building Embedded Linux Systems embedded Linux developers and include the speed of Building Embedded Linux Systems CPU, the size of the RAM, and the size of the permanent storage which might be a hard Building Embedded Linux Systems, but is often a flash device—currently either NOR or NAND, according to use. In terms of size, we will use three broad categories of systems: small, medium, and large. Remember to factor in the speed at which you could deploy Linux, though. Most consumer-oriented devices built with Linux belong to this category, including various PDAs for example, the Nokia Internet TabletsMP3 players, entertainment systems, and network appliances. Some of these devices may include secondary storage in the form of NAND Flash as much as 4 GB NAND Flash parts are available at the time of this writing; much larger size arrays are possible by combining more than one part, and we have seen systems using over 32 GB of NAND, even at the time that we are writing thisremovable memory cards, or even conventional hard drives. These types of devices have sufficient horsepower and storage to handle a variety of small tasks, or they can serve a single purpose that requires a lot of resources. Usually these systems are used in environments Building Embedded Linux Systems require large amounts of calculations to carry out certain tasks. Large telecom switches and flight simulators are prime examples of such systems, as are government research systems, defense projects, and many other applications that you would be unlikely to read about. Typically, such systems are not bound by costs or resources. Their design requirements are primarily based on functionality, while cost, size, and complexity remain secondary issues. This rules Building Embedded Linux Systems quite a number of processors traditionally used Building Embedded Linux Systems embedded systems. Fortunately Building Embedded Linux Systems, with the passage of time, increasing numbers of embedded designs are able to take advantage of Linux as processors become much more powerful and integrate increasing functionalityRAM and Flash prices fall, and other costs diminish. These days, it often makes less economic sense to deploy a new microcontroller design where for a small but not insignificant additional cost one can have all the power of a full Linux system—especially true when using ucLinux-supported devices. There have been Linux ports to a number of odd processors. The point here is that if you choose to use Linux on a processor lower than 32 bits, it Building Embedded Linux Systems absolutely certain that you will be on your own. Even if you get the kernel to boot, the range of applications is limited. There are two types of time constraints for embedded systems: stringent and mild. Stringent time constraints require that the system react in a predefined time frame; otherwise, ca tastrophic events happen. Take for instance a factory where workers have to handle materials being cut by large equipment. As a safety precaution, optical detectors are placed around the blades to detect the presence of the specially colored gloves used by the workers. This system has stringent time requirements; it is a hard real-time system. Streaming audio systems and consumer devices such as MP3 players and cell phones would also qualify as having stringent requirements, because any transient lagging in audio is usually perceived as bothersome by the users, and failure to contact a cellular tower within a certain time will result in an active call being dropped. In other words, although infrequent failures will Building Embedded Linux Systems tolerated—a call being dropped once in a while is an annoying frustration users already live with—the system should be designed to have stringent time requirements. The same is true for a PDA that takes a certain number of seconds to start an application. Nothing is more frustrating than not knowing whether a system is still working or has crashed. Networkability defines whether a system can be connected to a network. Nowadays, we can expect everything to be accessible through the network, even the refrigerator, toaster, and coffee machine indeed, a disturbing number of coffee machines can now download new coffee-making recipes Building Embedded Linux Systems. This, in turn, places special requirements on the systems being built. One factor pushing people to choose Linux as an Building Embedded Linux Systems OS is its proven networking capabilities. Falling prices and standardization of networking components are accelerating this trend. Most Linux devices have one form or another of network capability, be it wired or wireless in nature. The degree of user interaction varies greatly from one system to another. Some other systems have no user interface whatsoever. There are a wide range of motivations for choosing Linux over a traditional embedded OS. Many of these are shared by those in the desktop, server, and Building Embedded Linux Systems spaces, while others are more unique to the use of Linux in embedded devices. Building Embedded Linux Systems -

Goodreads helps you keep track of books you want to read. Want to Read saving…. Want to Read Currently Reading Read. Other editions. Enlarge Building Embedded Linux Systems. Error rating book. Refresh and try again. Open Preview See a Problem? Details if other Building Embedded Linux Systems. Thanks for telling us Building Embedded Linux Systems the problem. Return to Book Page. While there is a great deal of hype surrounding the use of Linux in embedded systems, there is not a lot of practical information. Building Embedded Linux Systems is the first in-depth, hard-core guide to putting together an embedded system based on the Linux kernel. This indispensable book features arcane and previously undocumented procedures for: Building your own GNU development toolchain Using an efficient embedded development framework Selecting, configuring, building, and installing a target-specific kernel Creating a complete target Building Embedded Linux Systems filesystem Setting up, manipulating, and using solid-state storage devices Installing and configuring a bootloader for Building Embedded Linux Systems target Cross-compiling a slew of utilities and packages Debugging your embedded system using a plethora of tools and techniques Details are provided for various target architectures and hardware configurations, including a thorough review of Linux's support for embedded hardware. All explanations rely on the use of open source and free software packages. By presenting how to build the operating system components from pristine sources and how to find more documentation or help, this book greatly simplifies the task of keeping Building Embedded Linux Systems control over one's embedded operating system, whether it be for technical or sound financial reasons. Author Karim Yaghmour, a well-known designer and speaker who is responsible for the Linux Trace Toolkit, starts by discussing the strengths and weaknesses of Linux as an embedded operating system. Licensing issues are included, followed by a discussion of the basics of building embedded Linux systems. The configuration, setup, and use of over forty different open source and free software packages commonly used in embedded Linux systems are also covered. Get A Copy. Paperbackpages. More Details Original Title. Other Editions Friend Reviews. To see what your friends thought of this book, please sign up. To ask other readers questions about Building Embedded Linux Systemsplease sign up. Be the first to ask a question about Building Embedded Linux Systems. Lists with This Book. This book is not yet featured on Listopia. Community Reviews. Showing Average rating 3. Rating details. More filters. Sort order. Start your review of Building Embedded Linux Systems. Jun 15, Christopher rated it really liked it. This is the best book I've found on embedded development. It covers everything and all that you'll need to do for getting Building Embedded Linux Systems real product done. Thank the maker he came out with a new edition. If you're working in this part of the industry you're probably looking for a book Building Embedded Linux Systems this that is going to make your job easier. I don't know about easy, but I wasted so much money on books that didn't do squat to help me get anything Building Embedded Linux Systems, a total waste of time. This book was a real help. I bought this book for its chapter on cross-compilation to setup a toolchain for building an ARM kernel on an existing linux box. There is also an interesting section on u-boot. Apr 11, Asutosh Satapathy rated it it was ok. Although the book has some good concepts, I believe the content is out of date. I stopped reading the book after the first 4 chapters. 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Simon Fisher rated it really liked it Oct 01, Nelson Faria rated it really liked it Aug 30, There are no discussion topics on this book yet. Readers also enjoyed. Goodreads is hiring! If you like books and love to build cool products, we may be looking for you. About Karim Yaghmour. Karim Yaghmour. Books by Karim Yaghmour. Escape the Present with These 24 Historical Romances. You know the saying: There's no time like the present In that case, we can't Read more Building Embedded Linux Systems About Building Embedded No trivia or quizzes yet. Welcome back. Just a moment while we sign you in to your Goodreads account.