Embedded Systems
and
Embedded Linux
Contents
1
INTRODUCTION
2
EMBEDDED LINUX
3
CONCLUSION
Embedded Systems & Embedded Linux
1.
INTRODUCTION
1.3
Examples
1.2
Characteristics
Of
ES
1.
INTRODUCITON
1.1
What & Why
Embedded
Systems?
1.4
Embedded OS
and
Why Linux?
1.5
History
of Linux and
Embedded
Linux
Embedded Systems & Embedded Linux
1.1 What & Why Embedded Systems?
1st: Information processing systems embedded
into enclosing products [1]
2nd: A special-purpose computer system designed
to perform one or a few dedicated functions,
often with real-time computing constraints [wiki]
3rd: System that consists of input/output (I/O) and
control logic stored in system firmware [2]
Embedded Systems & Embedded Linux
1.1 What & Why Embedded Systems?
The 1st recognizably modern embedded system:
The Apollo Guidance Computer (AGC) – 1960s
DSKY user interface
DSKY mounted on control panel
Embedded Systems & Embedded Linux
1.1 What & Why Embedded Systems?
WHY?
To make
hardware devices
more flexible:
+ Cost
+ Connectivity
+ Pervasive
Computing
+ Hardware
Combination
We are in the
post-PC era.
(2000 - 2020)
Embedded Systems & Embedded Linux
1.2
CHARACTERISTICS OF
EMBEDDED SYSTEMS
Real-time: + hard real-time (time critical constraints)
+ soft real-time (time sensitive constraints)
x86, Power PC, ARM, MIPS, 8051…hard-core or soft-core?
Dedicated to specific tasks
Power constraints
Wide range of Hardware
and Processors
Operating under extreme
environmental conditions
Software failure severity
Real-time constraints
Fewer system resources
than Desktop systems
Specialized tools and
Design methods
Using real-time
Operating systems (RTOS)
Dedicated
debugging circuitry
Cost sensitive
etc…
Embedded
Systems
≠
Desktop
Systems
Embedded Systems & Embedded Linux
1.3
EXAMPLES
TELECOMMUNICATIONS
MEDICAL
USERS’ DESIGNS
CONSUMER ELECTRONICS
Embedded
Systems
AUTOMOTIVE
INDUSTRY
Embedded Systems & Embedded Linux
1.4 WHY USING AN OPERATING SYSTEM?
WHY USING EMBEDDED LINUX?
1
Providing an abstraction layer for software
on top of the OS to be less dependent on hardware
→ Easier for middleware and applications designers
Why
Embedded
OSes
?
2
Managing various system hardware and software
resources → Provide more features
Embedded Systems & Embedded Linux
1.4 WHY USING AN OPERATING SYSTEM?
WHY USING EMBEDDED LINUX?
Low Cost
Varied Hardware Support
(scalable & flexible)
- Single to Multiprocessors
- Simple to Complex Systems
- Fully customizable in all its
components (thanks to GPL,
General Public License)
Powerful
High-performance
(Short Time to Market)
- Fast, High Efficiency
- Stable, low failure rate
- Rich set of toolsets and utilities
- Networking capabilities
- Development Cost
-Training and Hiring Costs
- Royalty free
- Low system maintenance time
OPEN SOURCE
Why
Embedded
Linux?
- Vendor Independence
- Thousands of developers
provide & enhance
Linux kernel and other
applications
- Global support
POSIX® Standards (IEEE)
Compliance
(Portable Operating
System Interface)
Increasing of supported hardware & software
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
- Linux / ’lɪnʊks / (original) or /’lɪnəks/ (English):
A “Unix-like” operating system.
UNIX???
Unix-like
UNIX
1969, AT&T
(Bell LABs)
UnixWare
Solaris
FreeBSD
…
OpenBSD
MINIX
IRIX
LINUX
Mac
OS X
AIX
Timeline of Unix variants
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
• / ’lɪnʊks / (original) or /’lɪnəks/ (English)
Linux
(or
• A “Unix-like” operating system.
GNU/Linux)
• Linux = Linux kernel 1.0 + GNU Project
Linus Torvalds
(created Linux
Kernel
in
1991)
Richard Matthew
Stallman
founder of
The GNU project
(from 1984)
Embedded Systems & Embedded Linux
1.5
GNU
HISTORY OF LINUX &
EMBEDDED LINUX
• A “Unix-like” operating system
• Created with free software
• Recursive acronym for “GNU's Not Unix”
(contain no UNIX code)
• GNU General Public License (GPL)
GNU Lesser General Public License (LGPL )
GNU Free Documentation License (FDL)
• GNU Compiler Collection (gcc)
GNU C Library (glibc)
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
Linux Distributions (Distros)
kernel + tools
+ window managers
+ many other applications
SUSE
Ubuntu
Debian
Red Hat /
Fedora
Mandriva
SUSE
(GNU/Linux)
Ret Hat
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
EMBEDDED LINUX (FIRST AGE)
1996
1997
Hard real-time No MMU
1999
Support
BlueCat
LynuxWorks
2000
New wave
BusyBox
0.43
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
Embedded Linux vs Other Embedded OSes
Linux
AMIRIX, Coollogic: Coollinux,
Coventive: Xlinux, Klinux,
Esfia: RedBlue Linux,
KYZO: PizzaBox Linux,
Lineo: Embedix,
LynuxWorks: BlueCat,
Neoware: NeoLinux,
TimeSys: Linux GPL,
MontaVista Linux
NonLinux
eCos ,
VxWorks,
Win CE,
Lynyos,
BSD,
Green Hills,
QNX
DOS
…
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
Linux kernel versions
Newest: 2.6.27.9-rc2
Embedded Systems & Embedded Linux
1.5
HISTORY OF LINUX &
EMBEDDED LINUX
Embedded Linux: Real-time or not?
General-purposes OS: NO REAL-TIME AT ALL!
(Differences in deterministic timing behavior of all the
OS services)
Past
1st Dual-kernel (Co-kernel) approach : hard real-time
2nd Fully Preemptive Kernel Approach:
Patches supported to make soft real-time Linux
NOW
Full real-time
Linux
Embedded Systems & Embedded Linux
2.
EMBEDDED LINUX
1
INTRODUCTION
2
EMBEDDED LINUX
3
CONCLUSION
Embedded Systems & Embedded Linux
2.
EMBEDDED LINUX
2.3
Prospects
2.2
Implementation
2.
EMBEDDED
LINUX
2.1
Design life
circle
2.4
Examples
for
FUTURE
2.5
Challenges
Embedded Systems & Embedded Linux
2.1
DESIGN LIFE CYCLE
Embedded Systems & Embedded Linux
2.1
DESIGN LIFE CYCLE
TRADITIONAL WORK-FLOW vs MODEL-BASED DESIGNED WORK-FLOW
PAST
NOW
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Examine . . .
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Simplified work-flow (suitable for individuals)
System Specifications
Overall Architecture /
Models
Hardware & software
configurations
Applications design
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Examine . . .
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 1: Product specifications / System requirements
-Build a Linux-based platform on a specific hardware
- Which hardware to choose (to order)?
+ Which development board?
Compatible with Linux or not?
+ Which processor?
- Which Linux distro? (that supports the chosen hardware)
- Which software and toolchain(s) to design?
Eclipse-based IDE(Integrated Development Environment)
- Which software application(s) to run?
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Examine . . .
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 2: Overall Architecture / Models
- Understand hardware’s architecture
Basic concepts
- Understand the Linux kernel
- Choosing hardware components
- Design block diagrams (at high level)
+ hardware connecting and behavior
+ application(s)
- Understand the cross-platform concept
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Examine . . .
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
EXAMPLE:
+ Board
+ CPU
Step 2: Overall Architecture / Models
- Understand hardware’s architecture
- Understand the Linux kernel
- Choosing hardware components
- Design block diagrams (at high level)
+ hardware connecting and behavior
+ application(s)
- Understand the cross-platform concept
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 2: Overall Architecture / Models
- Understand hardware’s architecture
+ Bus architecture
Ex:
IBM CoreConnect™ for Xilinx
Avalon Switch Fabric for Altera
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 2: Overall Architecture / Models
- Understand the Linux kernel (overall)
 The hardware abstraction layer (HAL)
HAL = BSPs + processor-specific software
 Memory manager
 Scheduler
 File system
 I/O subsystem
 Networking subsystem
 IPC (Inter-process communication)
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 2: Overall Architecture / Models
- Understand hardware’s architecture
- Understand the Linux kernel
- Choosing hardware components
- Design block diagrams (at high level)
+ hardware connecting and behavior
+ application(s)
- Understand the cross-platform concept
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 2: Overall Architecture / Models
- Understand the cross-platform concept
Host
Desktop
(Linux-x86)
Cross-Compiler
C libraries
Target’s hardware
drivers
Linux kernel
Configure & CrossCompile
Target
ARM, PPC,
MIPS, NIOS…
Boot loader
Kernel’s image
Root
filesystem
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Examine . . .
HOW TO BUILD A PARTICULAR
EMBEDDED LINUX SYSTEM?
Step 3: Hardware and Software configurations
HARDWARE: (Work becomes more easier with powerful tools)
- Configure the CPU parameters
+ processor clock frequency, bus clock frequency
+ Cache/ debug mode/ On-chip memory?
- Configure the peripherals
+ Using own designs (verilog .v or .vhdl files)
+ Using supported / licensed IP cores (Intellectual Properties)
+ Enabled / Disabled – interrupt or not?
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 3: Hardware and Software configurations
HARDWARE: (Work becomes more easier with powerful tools)
- Configure Software setting
+ Give more detailed information to the System Wizard
+ Choose the embedded OS
+ Connected peripherals
- Build and generate file Netlist + bitstream (will be uploaded to the FPGA )
- Generate software Libraries and BSP (Board Support Packages)
BSP includes:
+ drivers
+ header files
+ device ID number
+system address map
will be used in the kernel compilation process
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 3: Hardware and Software configurations
SOFTWARE: (need to deal a lot with the Linux command console)
-Preparations for cross-compilation of the kernel
Create a cross-compiler environment (to compile CPU kernel
and Linux root file system)
Crosstool: reliable & easy-to-use toolchain generator
(by Dan Kegel)
• Linux kernel headers
• C libraries
Crosstool Proper toolchain
(suitable versions
(GCC – GNU Compiler Collection )
(scripts) for target hardware)
(glibc)
• Binutils(manipulate binary object files)
•…
- Build the Linux kernel
• Download the Linux kernel (with the distro supporting the hardware)
• Insert the BSP files + make some necessary modifications
(Created before)
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 3: Hardware and Software configurations
SOFTWARE: (need to deal a lot with the Linux command console)
- Build the Linux kernel (cont)
• Compile the kernel → make kernel’s image (.elf – executable and linking format)
• Test the kernel without Root file system (optional)
- Build Root filesystem (RFS)
• Using BusyBox
Run a script file to:
+ Create root directories
+ Copy Glibc into RFS folder
+ Install BusyBox into RFS
+ Modifies permissions and
ownerships of RFS
• Re-configure the kernel
• Re-make the final image
(.ace file - to load into the flash-card)
Top-level directories
Directory Contents
bin Binary executables, usable by all users on
the system
dev Device nodes
etc Local system-configuration files
lib System libraries, such as the standard C
library and many others
sbin Binary executables usually reserved for
superuser accounts on the system
usr A secondary file system hierarchy for
application programs, usually read-only
var Contains variable files, such as system
logs and temporary configuration files
tmp Temporary files
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 3: Hardware and Software configurations
SOFTWARE: (need to deal a lot with the Linux command console)
- Port kernel image into hardware
• Format CF card (flash card):
Partition 1: Type = FAT16 (6) (contains created .ace file)
Partition 2: Type = Linux Swap (82) Size = 1 ~ 1.5 main memory
Partition 3: Type = Linux (83), Size = Remainder disk space (contains NFS files)
• Copy .ace file
→ partition 1
NFS files → partition 3
PORT LINUX KERNEL FINISH!!!
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
Step 4: Applications design
- Similar to programming applications in desktop
+ Assembly, Pascal, C, C++, Java…
+ Block diagram
+ Coding (on host PC)
+…
+ Cross-compile → executable files in target device
- Copy into /bin on root file system of target.
SYSTEM COMPLETED!!!
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
SOME REAL EMBEDDED LINUX SYSTEMS TODAY
LINUX KERNEL PORTED TO IPHONE
(iPhone-Dev.org)
- Hardware: Iphone (fixed) 1st & 2nd generation + Touch
Processor: ARM
- Bootloader: OpeniBoot
- Linux kernel: 2.6
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
SOME REAL EMBEDDED LINUX SYSTEMS TODAY
www.mtemag.com
Hardware: Airbus380
25 PowerPC processors
OS: LynxOS (Linux-based real-time OS)
Embedded Systems & Embedded Linux
2.2
IMPLEMENTATION
SOME REAL EMBEDDED LINUX SYSTEMS TODAY
ANDROID – FUTURE’S HAND HELD OS
android.com
- Developers: Open Handset Alliance
(Google, Intel, Motorola, T-mobile… )
on November 2007
- Hardware: mobile devices
- OS: Android (Linux kernel (monolithic))
- Software development kit: Android SDK
T-mobile G1: 1st mobile device using Android 1.0 OS
Embedded Systems & Embedded Linux
2.3
PROSPECTS
- 3rd wave of innovation in ICT (Post-PC era)
99% of global processors are placed in Embedded Systems.
-Combine advantages of many industries together
(ITC, Mechanics, Biology, Chemistry… )
- With an eOS + a powerful design toolchain,
Embedded Systems can approach any kind of user and
are much easier to build your own system. (flexibility)
+ Xilinx ISE development suites
+ Altera Stratix II Development Kit
+ Embedded MATLAB:using Model-Based Design
+…
Embedded Systems & Embedded Linux
2.4
FUTURE’S EXAMPLES
- SoC evolutions → NoC (Network on Chip)
Spidergon Topology + IPU (Interconnect Processing Unit)
→ Spidergon STNoC: an innovative technology
Embedded Systems & Embedded Linux
2.4
FUTURE’S EXAMPLES
NoC
Using GALS
(Globally Asynch. Locally Sync.)
Embedded Systems & Embedded Linux
2.4
FUTURE’S EXAMPLES
Ambient Intelligence:
Many networked devices are integrated into the environment.
Embedded Systems & Embedded Linux
2.5
CHALLENGES & LIMITATIONS
- Difficulties in HW/SW co-design.
- Multi-careers co-ordination
- Linux:
+ Open source
+ Unfamiliar with Windows users
Viet Nam’s reality:
- Hardware’s un-afordable (software only)
Embedded Systems & Embedded Linux
REFERENCE
[1] Arnold S. Berger - Embedded Systems Design- An Introduction to Processes,
Tools and Techniques (CMP Books - 2002)
[2] Craig Hollabaugh - Embedded Linux- Hardware, Software and Interfacing
(Addison Wesley) – 2002
[3] Auerbach - Embedded Linux System Design and Development (2006)
[4] Newnes - Embedded Software - Know it all - Sep 2007
[5] Karim Yaghmour Building Embedded Linux Systems - 2nd edition - Aug.2008
(OReilly)
[6] O'Reilly - Understanding The Linux Kernel (2000)
[7] Prentice Hall - Embedded Linux Primer - a Practical RealWorld Approach 2006
[8] Prentice Hall- The Linux Kernel Primer A Top Down Approach
for x86 and PowerPC Architectures – 2005
[9] PETER MARWEDEL - Embedded System Design - Peter Marwedel -2006
(Springer)
[10] Embedded System WEEK08_tutorial Slides
[11] J. W. Donaldson - Porting MontaVista Linux to the XUP Virtex-II Pro
development board - 2006
Embedded Systems & Embedded Linux