Embedded Operating Systems: A Practical Approach

244 Pages·2018·5.9 MB·English

by  Alan Holt

Undergraduate Topics in Computer Science
Alan Holt
Chi-Yu Huang
Embedded
Operating
Systems
A Practical Approach
Second Edition
Undergraduate Topics in Computer
Science
Series editor
Ian Mackie
Advisory Board
Samson Abramsky, University of Oxford, Oxford, UK
Chris Hankin, Imperial College London, London, UK
Mike Hinchey, University of Limerick, Limerick, Ireland
Dexter C. Kozen, Cornell University, Ithaca, USA
Andrew Pitts, University of Cambridge, Cambridge, UK
HanneRiisNielson,TechnicalUniversityofDenmark,KongensLyngby,Denmark
Steven S. Skiena, Stony Brook University, Stony Brook, USA
Iain Stewart, University of Durham, Durham, UK
UndergraduateTopics inComputerScience (UTiCS) delivers high-qualityinstruc-
tionalcontentforundergraduatesstudyinginallareasofcomputingandinformation
science. From core foundational and theoretical material to final-year topics and
applications,UTiCSbookstakeafresh,concise,andmodernapproachandareideal
for self-study or for a one- or two-semester course. The texts are all authored by
establishedexpertsintheirfields,reviewedbyaninternationaladvisoryboard,and
containnumerous examples and problems. Manyincludefullyworked solutions.
More information about this series at http://www.springer.com/series/7592
Alan Holt Chi-Yu Huang
(cid:129)
Embedded Operating
Systems
A Practical Approach
Second Edition
123
AlanHolt Chi-Yu Huang
ZeettaNetworks GE Aviation Systems
Bristol Cheltenham
UK UK
ISSN 1863-7310 ISSN 2197-1781 (electronic)
Undergraduate Topics inComputer Science
ISBN978-3-319-72976-3 ISBN978-3-319-72977-0 (eBook)
https://doi.org/10.1007/978-3-319-72977-0
LibraryofCongressControlNumber:2017962063
1stedition:©Springer-VerlagLondon2014
2ndedition:©SpringerInternationalPublishingAG,partofSpringerNature2018
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In memory of Marjorie Rose Holt and
Siou-yìn Zheng Huang
Preface to the Second Edition
Sincethefirstedition,operatingsystemsandthesoftwarepackagesthatarebundled
with them have progressed. Nowadays, 64-bit desktop/laptop computers are com-
monplace. This was not the case when the first edition was published. There are
some 64-bit architectures that are used for embedded platforms but 32-bit (or less)
machines are still prevalent. Whereas in the first edition we would be building
softwarefor32-bittargetson32-bithosts,wenowneedtocross-compileon64-bit
hosts. In the real-world, this is what would be done but it does add a level of
complexity to the practical exercises in this book.
Furthermore, the work examples in this book have software dependencies
(utilities and shared libraries). Not only that, particular versions of these depen-
denciesarerequired.Inthefirstedition, we addressed thisissuebyrecommending
thereaderusethesameoperatingsystemplatform thattheauthorsusedtodevelop
theexercises.Thisisnotreallypractical,notleastfortheauthorsthemselvesgiven
that dependency versions have moved on since the first edition.
For these reasons, we have introduced some new technologies in this edition.
First,we make useofvirtual machines. We usedvirtual machine technology, such
as user mode Linux (UML), in the first edition as a means of testing operating
systembuilds.Inthisedition,weuseVirtualBoxsothatwecanbuildsoftwareona
(virtualized) 32-bit platform even though our host machine may be 64-bit. This
obviates the need to cross-compile.
We rely heavily on Linux container technology to build software, namely,
Docker. Docker is a container system which enables us to replicate environments
and ensure commonality between the authors’ and the reader’s respective devel-
opmentplatforms.Aswellashelpingustobuildoperatingsystems,itisalsouseful
fortesting. WededicateawholenewchaptertoDockerand itsuses asameans of
introducing the technology.
Bristol, UK Alan Holt
Cheltenham, UK Chi-Yu Huang
vii
Preface to the First Edition
Most people are aware of the mainstream operating systems such as Microsoft‘s
Windows or Apple’s macOS. This is because these are the operating systems that
they directly interact with on their personal computers. However, personal com-
puters rarely operate in isolation nowadays.
Manycomputingapplicationsrequireonlineaccess.AccesstotheInternetrelies
on many computing systems, for example, Ethernet switches, packet routers,
wireless access points, and DHCP and DNS servers. Unlike personal computers,
network infrastructure equipments performdedicatedtasks andare often described
as “embedded systems”.
The term “embedded system” covers a range of computing systems. It derives
fromcomputingsystemsthatareembeddedwithinsomelargerdevice,forexample,
as part of a car’s engine management system. The term has broadened to cover
stand-alone systems too. Nor is it limited to network infrastructure systems or
consumergoodssuchassatellitenavigationdevices.Theterm“embeddedsystem”
is applied to devices which are small and have limited resources (relative to a
personalcomputer).Mobiledevicessuchassmartphonesandtabletsare,therefore,
described as embedded devices, even though their function closely resembles a
personal computer. Nevertheless, an embedded system needs an operating system
specific to its needs, for example,
(cid:129) Small form factor.
(cid:129) Low processing power and small memory.
(cid:129) Reduced power consumption for battery longevity.
(cid:129) Support for real-time applications.
There are many embedded operating systems available; however, in this book
we confine our discussion to the GNU/Linux operating system. GNU/Linux is not
exclusively an embedded operating system and is used on personal computers and
servers just like Windows and macOS. However, due to its open-source nature it
can be easily adapted to many environments. For this reason, GNU/Linux systems
have gained considerable popularity in the embedded system market.
ThatisnottosaythatGNU/Linuxisapanaceaforembeddedsystemsandthere
are many excellent alternatives. Nevertheless, there are some good reasons for
choosing GNU/Linux:
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x PrefacetotheFirstEdition
(cid:129) GNU/Linux is open source and is freely available.
(cid:129) Due to its open-source nature, GNU/Linux is highly customizable so we can
build bespoke systems specific to our needs.
(cid:129) It is widely used for embedded systems.
(cid:129) GNU/Linux, like its Unix predecessor, was used extensively in education to
teach operating systems.
(cid:129) While the subject of the book is embedded operating systems, our choice of
GNU/Linux means it could be used as a text for a more general course on
operating systems.
Operatingsystemsisadiversesubjectareaandtherearemanybooksonthesubject
and of GNU/Linux alone. A variety of topics are covered including the kernel,
administration, networking, wireless, high-performance computing, and systems
programming(tonamebutafew).ThereareevenbooksonGNU/Linuxembedded
systems.
However, we felt there was a gap in the literature which described the com-
ponents parts of an operating system and how they worked together. We address
these issues in this book by adopting a practical approach. The procedure for
building each component of the operating system, namely, the bootloader, kernel,
filesystem,sharedlibraries,start-upscripts,configurationfiles,andsystemutilities,
fromitssourcecode,isdescribedindetail.Bytheendofthisbook,thereaderwill
be able to build a fully functional GNU/Linux embedded operating system.
This book is not an introductory text on operating systems, rather it is aimed at
undergraduate/graduate level students and industry professionals.
Acknowledgements
The authors would like to thank Dr. Adrian Davies and Justin Johnstone for their
valuable contributions to this book.
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