1.4 Standards and Relevant Bodies5software. It guarantees your freedom to use it, study it, and change it. It also guaranteesthesefreedoms foranyone towhom youdistributeyour modified code.This concepthasbecomefairlywidelyunderstood.One of the misconceptions frequently heard is that Linux is“free as in beer."Youcan obtain Linux free of cost. You can download a Linux kernel in a few minutes.However, as any professional development manager understands, certain costs are as-sociated with any software to be incorporated into a design.These include the costs ofacquisition,integration,modification,maintenance,and support.Add to thatthecostof obtaining and maintaining a properly configured toolchain, libraries, applicationprograms, and specialized cross-development tools compatible with your chosen archi-tecture, and you can quickly see that it is a nontrivial exercise to develop the neededsoftware components and development environment necessarytodevelop and deployyour embedded Linux-based system.1.4Standards andRelevantBodiesAs Linux continues to gain market share in the desktop, enterprise, and embeddedmarket segments, new standards and organizations have emerged to help influence theuse and acceptance of Linux.This section introduces the standards you might want tofamiliarizeyourselfwith.1.4.1LinuxStandardBaseProbably the single most relevant standard for a Linux distribution maintainer is theLinuxStandard Base (LSB).Thegoal of theLSB is toestablisha setof standardsdesigned to enhance the interoperability of applications among different Linux dis-tributions.Currently,theLSB spans several architectures, including IA32/64,PowerArchitecture 32-and 64-bit,AMD64,and others.The standard is divided into a corecomponent and the individual architectural components.The LSB specifies common attributes of a Linux distribution, including object for-mat, standard library interfaces, a minimum set of commands and utilities and theirbehavior,filesystemlayout, systeminitialization,and soon.You can learn more about the LSB at the link given at the end of this chapter
ptg 1.4 Standards and Relevant Bodies 5 software. It guarantees your freedom to use it, study it, and change it. It also guarantees these freedoms for anyone to whom you distribute your modified code. This concept has become fairly widely understood. One of the misconceptions frequently heard is that Linux is “free as in beer.” You can obtain Linux free of cost. You can download a Linux kernel in a few minutes. However, as any professional development manager understands, certain costs are associated with any software to be incorporated into a design. These include the costs of acquisition, integration, modification, maintenance, and support. Add to that the cost of obtaining and maintaining a properly configured toolchain, libraries, application programs, and specialized cross-development tools compatible with your chosen architecture, and you can quickly see that it is a nontrivial exercise to develop the needed software components and development environment necessary to develop and deploy your embedded Linux-based system. 1.4 Standards and Relevant Bodies As Linux continues to gain market share in the desktop, enterprise, and embedded market segments, new standards and organizations have emerged to help influence the use and acceptance of Linux. This section introduces the standards you might want to familiarize yourself with. 1.4.1 Linux Standard Base Probably the single most relevant standard for a Linux distribution maintainer is the Linux Standard Base (LSB). The goal of the LSB is to establish a set of standards designed to enhance the interoperability of applications among different Linux distributions. Currently, the LSB spans several architectures, including IA32/64, Power Architecture 32- and 64-bit, AMD64, and others. The standard is divided into a core component and the individual architectural components. The LSB specifies common attributes of a Linux distribution, including object format, standard library interfaces, a minimum set of commands and utilities and their behavior, file system layout, system initialization, and so on. You can learn more about the LSB at the link given at the end of this chapter. Download at www.wowebook.com
Chapter1 Introduction61.4.2LinuxFoundationAccording to its website, the Linux Foundation“is a non-profit consortium dedicatedto fostering the growth of Linux."The Linux Foundation sponsors the work of LinusTorvalds, the creator of Linux.The Linux Foundation sponsors several working groupsto define standards and participate in thedevelopment of features targetingmany im-portant Linux platform attributes.The next two sections introduce some of these ini-tiatives.1.4.3Carrier-Grade LinuxA significant number of the world's largest networking and telecommunications equip-ment manufacturers are either developing or shipping carrier-class equipment runningLinux as the operating system. Significant features of carrier-class equipment includehigh reliability,high availability, and rapid serviceability.These vendors design prod-ucts using redundant hot-swap architectures, fault-tolerant features, clustering, andoftenreal-timeperformance.TheLinux Foundation Carrier GradeLinux workgroup has produced a specifica-tion defining a set of requirements for carrier-class equipment. The current version ofthe specification covers sevenfunctionalareas:·Availability—Requirements that provide enhanced availability, includingonlinemaintenanceoperations,redundancy,and statusmonitoringClusters-Requirements that facilitate redundant services, such as clustermembership management and data checkpointing.Serviceability-Requirements for remote servicing andmaintenance, such asSNMP and diagnostic monitoring of fans and power suppliesPerformance-Requirementstodefineperformanceand scalability,symmetricmultiprocessing,latencies,andmore.StandardsRequirements that define standards to which CGL-compliantequipment shall conformHardware-Requirements related to high-availability hardware, such as bladeservers and hardware-management interfaces.Security-Requirements to improve overall system security and protect thesystemfrom variousexternalthreats
ptg 6 Chapter 1 Introduction 1.4.2 Linux Foundation According to its website, the Linux Foundation “is a non-profit consortium dedicated to fostering the growth of Linux.” The Linux Foundation sponsors the work of Linus Torvalds, the creator of Linux. The Linux Foundation sponsors several working groups to define standards and participate in the development of features targeting many important Linux platform attributes. The next two sections introduce some of these initiatives. 1.4.3 Carrier-Grade Linux A significant number of the world’s largest networking and telecommunications equipment manufacturers are either developing or shipping carrier-class equipment running Linux as the operating system. Significant features of carrier-class equipment include high reliability, high availability, and rapid serviceability. These vendors design products using redundant hot-swap architectures, fault-tolerant features, clustering, and often real-time performance. The Linux Foundation Carrier Grade Linux workgroup has produced a specification defining a set of requirements for carrier-class equipment. The current version of the specification covers seven functional areas: • Availability—Requirements that provide enhanced availability, including online maintenance operations, redundancy, and status monitoring • Clusters—Requirements that facilitate redundant services, such as cluster membership management and data checkpointing • Serviceability—Requirements for remote servicing and maintenance, such as SNMP and diagnostic monitoring of fans and power supplies • Performance—Requirements to define performance and scalability, symmetric multiprocessing, latencies, and more • Standards—Requirements that define standards to which CGL-compliant equipment shall conform • Hardware—Requirements related to high-availability hardware, such as blade servers and hardware-management interfaces • Security—Requirements to improve overall system security and protect the system from various external threats Download at www.wowebook.com
1.4Standards and Relevant Bodies71.4.4MobileLinuxInitiative:MoblinSeveral mobile handsets (cellular phones)available on the worldwide market have beenbuilt around embedded Linux.It has been widely reported that tens of millions ofhandsets have been shipped with Linux as the operating system platform.The only cer-tainty is that more are coming.This promises to be one of the most explosive marketsegments for what was formerly the role of a proprietary real-time operating system.This speaks volumes about thereadiness of Linuxfor commercial embedded applica-tions.The Linux Foundation sponsors a workgroup originally called the Mobile LinuxInitiative,nowreferred to as Moblin.Its purpose is to acceleratethe adoption of Linuxon next-generationmobilehandsets and otherconvergedvoice/dataportabledevices,according to the Linux Foundation website.The areas of focus for this working groupinclude development tools, I/O and networking, memory management, multimedia,performance, power management, security, and storage.The Moblin website can befound at http://moblin.org.You can try out a Moblin release, such as Fedora/Moblin,foundathttp://fedoraproject.org/wiki/Features/FedoraMoblin,ortheUbuntuMoblinremixfound ontheauthor'sDellMini1oNetbook.The embedded Linux landscape is continuously evolving. As this second editionwas being prepared, the Moblin and Maemo project merged to become MeeGo.You can learn more about MeeGo, and even download a MeeGo image to try out, athttp://meego.com/.1.4.5ServiceAvailabilityForumIf you are engaged in building products for environments in which high reliability,availability,and serviceability (RAS)are important,you should be aware of the ServiceAvailability Forum (SA Forum).This organization is playing a leading role in defininga common set of interfaces for use in carrier-grade and other commercial equipmentforsystemmanagement.The SAForum website is atwww.saforum.org
ptg 1.4 Standards and Relevant Bodies 7 1.4.4 Mobile Linux Initiative: Moblin Several mobile handsets (cellular phones) available on the worldwide market have been built around embedded Linux. It has been widely reported that tens of millions of handsets have been shipped with Linux as the operating system platform. The only certainty is that more are coming. This promises to be one of the most explosive market segments for what was formerly the role of a proprietary real-time operating system. This speaks volumes about the readiness of Linux for commercial embedded applications. The Linux Foundation sponsors a workgroup originally called the Mobile Linux Initiative, now referred to as Moblin. Its purpose is to accelerate the adoption of Linux on next-generation mobile handsets and other converged voice/data portable devices, according to the Linux Foundation website. The areas of focus for this working group include development tools, I/O and networking, memory management, multimedia, performance, power management, security, and storage. The Moblin website can be found at http://moblin.org. You can try out a Moblin release, such as Fedora/Moblin, found at http://fedoraproject.org/wiki/Features/FedoraMoblin, or the Ubuntu Moblin remix found on the author’s Dell Mini 10 Netbook. The embedded Linux landscape is continuously evolving. As this second edition was being prepared, the Moblin and Maemo project merged to become MeeGo. You can learn more about MeeGo, and even download a MeeGo image to try out, at http://meego.com/. 1.4.5 Service Availability Forum If you are engaged in building products for environments in which high reliability, availability, and serviceability (RAS) are important, you should be aware of the Service Availability Forum (SA Forum). This organization is playing a leading role in defining a common set of interfaces for use in carrier-grade and other commercial equipment for system management. The SA Forum website is at www.saforum.org. Download at www.wowebook.com
8Chapter 1Introduction1.5SummaryEmbedded Linux has won the race. Indeed, you probably have embedded Linux inyour car or home. This chapter examined the reasons why and developed a perspectivefor the material to come::Adoption of Linuxamongdevelopers andmanufacturers of embedded prod-ucts continues to accelerate..Use of Linux in embedded devices continues to growatan excitingpace.Many factors are driving the growth of Linux in the embedded market.·Several standards and relevant organizations are influencing embedded Linux.1.5.1Suggestions forAdditional ReadingThe Cathedral and the BazaarEric S. RaymondO'Reilly Media, Inc., 2001Linux Standard Base Projecthttp://www.linuxfoundation.org/collaborate/workgroups/lsbLinux Foundationhttp://www.linuxfoundation.org
ptg 8 Chapter 1 Introduction 1.5 Summary Embedded Linux has won the race. Indeed, you probably have embedded Linux in your car or home. This chapter examined the reasons why and developed a perspective for the material to come: • Adoption of Linux among developers and manufacturers of embedded products continues to accelerate. • Use of Linux in embedded devices continues to grow at an exciting pace. • Many factors are driving the growth of Linux in the embedded market. • Several standards and relevant organizations are influencing embedded Linux. 1.5.1 Suggestions for Additional Reading The Cathedral and the Bazaar Eric S. Raymond O’Reilly Media, Inc., 2001 Linux Standard Base Project http://www.linuxfoundation.org/collaborate/workgroups/lsb Linux Foundation http://www.linuxfoundation.org/ Download at www.wowebook.com
2ChapterThe Big PictureInThisChapter10■ 2.1Embedded orNot?12 2.2Anatomy of an Embedded System202.3StorageConsiderations322.4Embedded LinuxDistributions342.5Summary9
ptg 9 2 The Big Picture In This Chapter ■ 2.1 Embedded or Not? 10 ■ 2.2 Anatomy of an Embedded System 12 ■ 2.3 Storage Considerations 20 ■ 2.4 Embedded Linux Distributions 32 ■ 2.5 Summary 34 Download at www.wowebook.com