AbouttheAuthorSreekrishnanVenkateswaranhasa master'sdegreein computersciencefromtheIndianInstituteofTechnology, Kanpur, India. During the past 12 years that he has been working for IBM, he has ported Linux tovariousembedded devices suchasawristwatch,handheld,musicplayer,VoiPphone,pacemakerprogrammer,and remote patient monitoring system.Sreekrishnan was a contributing editor and kernel columnist to theLinuxMagazinefor more than 2years.Currently, he manages the embedded solutions group at IBM India
About the Author Sreekrishnan Venkateswaran has a master's degree in computer science from the Indian Institute of Technology, Kanpur, India. During the past 12 years that he has been working for IBM, he has ported Linux to various embedded devices such as a wristwatch, handheld, music player, VoIP phone, pacemaker programmer, and remote patient monitoring system. Sreekrishnan was a contributing editor and kernel columnist to the Linux Magazine for more than 2 years. Currently, he manages the embedded solutions group at IBM India
Chapter 1.IntroductionIn This Chapter2.Evolution3TheGNU Copyleft4Kernel.orgXMailing ListsandForums5LinuxDistributions6LookingattheSources10.Building theKernel12LoadableModules14·BeforeStarting
Chapter 1. Introduction In This Chapter Evolution 2 The GNU Copyleft 3 Kernel.org 4 Mailing Lists and Forums 4 Linux Distributions 5 Looking at the Sources 6 Building the Kernel 10 Loadable Modules 12 Before Starting 14
Linuxlures.Ithastheenticingaroma ofan internationalistprojectwherepeopleof allnationalities,creed,and gender collaborate.Free availability of source codeand a well-understoodUNIX-likeapplicationprogrammingenvironment havecontributed to its runaway success.High-qualitysupportfromexpertsavailableinstantlyovertheInternetatnochargehasalsoplayedamajor role institchingtogetherahuge LinuxcommunityDevelopers get incredibly excited about working on technologies where they have access to all thesourcesbecause that lets them createinnovative solutions.You can,for example,hack thesourcesandcustomizeLinuxtobootinafewsecondsonyourdevice,afeatthat ishardto achievewithaproprietaryoperating system.EvolutionLinuxstartedasthehobbyofaFinnishcollegestudentnamedLinusTorvaldsin1991,butquicklymetamorphedinto an advanced operating system popular all over the planet. From its first release for the Intel 386 processor,thekernel hasgraduallygrown in complexitytosupportnumerousarchitectures,multiprocessorhardware,andhigh-performanceclusters.Thefull listof supportedCPUsislong,but someofthemajorsupportedarchitecturesarex86,IA64,ARM,PowerPC,Alpha,s390,MIPS,andSPARC.Linuxhasbeenportedtohundredsof hardwareplatformsbuilt around theseprocessors.Thekernel is continuouslygettingbetter,andtheevolutionisprogressingatafranticpace.Although it started life as a desktop-operating system, Linux has penetrated the embedded and enterpriseworlds and is touching our daily lives.Whenyoupush the buttons on your handheld, flipyour remoteto theweatherchannel, or visit the hospital for a physical checkup,it's increasingly likelythat some Linux code isbeing set into motion to come to your service.Linux's freeavailability is helping its evolution as much as itstechnical superiority.Whetherit'san initiativeto develop sub-$1oo computersto enabletheworld'spoor orpricingpressureintheconsumerelectronicsspace,Linuxistoday'soperatingsystemofchoice,becauseproprietary operating systems sometimes cost morethan the desired price of the computers themselves.4
Linux lures. It has the enticing aroma of an internationalist project where people of all nationalities, creed, and gender collaborate. Free availability of source code and a well-understood UNIX-like application programming environment have contributed to its runaway success. Highquality support from experts available instantly over the Internet at no charge has also played a major role in stitching together a huge Linux community. Developers get incredibly excited about working on technologies where they have access to all the sources because that lets them create innovative solutions. You can, for example, hack the sources and customize Linux to boot in a few seconds on your device, a feat that is hard to achieve with a proprietary operating system. Evolution Linux started as the hobby of a Finnish college student named Linus Torvalds in 1991, but quickly metamorphed into an advanced operating system popular all over the planet. From its first release for the Intel 386 processor, the kernel has gradually grown in complexity to support numerous architectures, multiprocessor hardware, and high-performance clusters. The full list of supported CPUs is long, but some of the major supported architectures are x86, IA64, ARM, PowerPC, Alpha, s390, MIPS, and SPARC. Linux has been ported to hundreds of hardware platforms built around these processors. The kernel is continuously getting better, and the evolution is progressing at a frantic pace. Although it started life as a desktop-operating system, Linux has penetrated the embedded and enterprise worlds and is touching our daily lives. When you push the buttons on your handheld, flip your remote to the weather channel, or visit the hospital for a physical checkup, it's increasingly likely that some Linux code is being set into motion to come to your service. Linux's free availability is helping its evolution as much as its technical superiority. Whether it's an initiative to develop sub-$100 computers to enable the world's poor or pricing pressure in the consumer electronics space, Linux is today's operating system of choice, because proprietary operating systems sometimes cost more than the desired price of the computers themselves
Chapter 1.IntroductionIn This Chapter2.Evolution3TheGNU Copyleft4Kernel.orgXMailing ListsandForums5LinuxDistributions6LookingattheSources10.Building theKernel12LoadableModules14·BeforeStarting
Chapter 1. Introduction In This Chapter Evolution 2 The GNU Copyleft 3 Kernel.org 4 Mailing Lists and Forums 4 Linux Distributions 5 Looking at the Sources 6 Building the Kernel 10 Loadable Modules 12 Before Starting 14
Linuxlures.Ithastheenticingaroma ofan internationalistprojectwherepeopleof allnationalities,creed,and gender collaborate.Free availability of source codeand a well-understoodUNIX-likeapplicationprogrammingenvironment havecontributed to its runaway success.High-qualitysupportfromexpertsavailableinstantlyovertheInternetatnochargehasalsoplayedamajor role institchingtogetherahuge LinuxcommunityDevelopers get incredibly excited about working on technologies where they have access to all thesourcesbecause that lets them createinnovative solutions.You can,for example,hack thesourcesandcustomizeLinuxtobootinafewsecondsonyourdevice,afeatthat ishardto achievewithaproprietaryoperating system.EvolutionLinuxstartedasthehobbyofaFinnishcollegestudentnamedLinusTorvaldsin1991,butquicklymetamorphedinto an advanced operating system popular all over the planet. From its first release for the Intel 386 processor,thekernel hasgraduallygrown in complexitytosupportnumerousarchitectures,multiprocessorhardware,andhigh-performanceclusters.Thefull listof supportedCPUsislong,but someofthemajorsupportedarchitecturesarex86,IA64,ARM,PowerPC,Alpha,s390,MIPS,andSPARC.Linuxhasbeenportedtohundredsof hardwareplatformsbuilt around theseprocessors.Thekernel is continuouslygettingbetter,andtheevolutionisprogressingatafranticpace.Although it started life as a desktop-operating system, Linux has penetrated the embedded and enterpriseworlds and is touching our daily lives.Whenyoupush the buttons on your handheld, flipyour remoteto theweatherchannel, or visit the hospital for a physical checkup,it's increasingly likelythat some Linux code isbeing set into motion to come to your service.Linux's freeavailability is helping its evolution as much as itstechnical superiority.Whetherit'san initiativeto develop sub-$1oo computersto enabletheworld'spoor orpricingpressureintheconsumerelectronicsspace,Linuxistoday'soperatingsystemofchoice,becauseproprietary operating systems sometimes cost morethan the desired price of the computers themselves.4
Linux lures. It has the enticing aroma of an internationalist project where people of all nationalities, creed, and gender collaborate. Free availability of source code and a well-understood UNIX-like application programming environment have contributed to its runaway success. Highquality support from experts available instantly over the Internet at no charge has also played a major role in stitching together a huge Linux community. Developers get incredibly excited about working on technologies where they have access to all the sources because that lets them create innovative solutions. You can, for example, hack the sources and customize Linux to boot in a few seconds on your device, a feat that is hard to achieve with a proprietary operating system. Evolution Linux started as the hobby of a Finnish college student named Linus Torvalds in 1991, but quickly metamorphed into an advanced operating system popular all over the planet. From its first release for the Intel 386 processor, the kernel has gradually grown in complexity to support numerous architectures, multiprocessor hardware, and high-performance clusters. The full list of supported CPUs is long, but some of the major supported architectures are x86, IA64, ARM, PowerPC, Alpha, s390, MIPS, and SPARC. Linux has been ported to hundreds of hardware platforms built around these processors. The kernel is continuously getting better, and the evolution is progressing at a frantic pace. Although it started life as a desktop-operating system, Linux has penetrated the embedded and enterprise worlds and is touching our daily lives. When you push the buttons on your handheld, flip your remote to the weather channel, or visit the hospital for a physical checkup, it's increasingly likely that some Linux code is being set into motion to come to your service. Linux's free availability is helping its evolution as much as its technical superiority. Whether it's an initiative to develop sub-$100 computers to enable the world's poor or pricing pressure in the consumer electronics space, Linux is today's operating system of choice, because proprietary operating systems sometimes cost more than the desired price of the computers themselves