Linux For Embedded Systems For Arabs

Ahmed ElArabawy

New Trends in Embedded Systems

Myths on Embedded Systems

More Hardware than Software

Applications are Trivial

Interfacing with sensors

Measuring temperature, pressure, light,

Controlling a motor

Controlling some light switches

etc.

No need for Operating System support

Why do we needs an OS this is Just an Embedded System

Code in low level languages

Some even consider all in Assembly

Code fully customized on Hardware

The center piece is the hardware, and SW will be tailored to it

Code is very close to the Hardware

Is this True ??

This impression is TRUE in some embedded systems

But not true for a great portion of the market

The reason for this impression

Education (No advanced embedded system courses)

Toy projects and hobbyists (most focus on microcontrollers)

Cost of Hardware

Background

Application

Limited exposure to industry

Reality is ..

Most embedded systems are much more sophisticated, Use of multicore is becoming very common

Multi-core can be homogeneous or heterogeneous

Big.Little Architecture

Dedicated cores to manage operation of the other cores

Special H/W Accelerators for low level functionality

Use of Operating Systems is unavoidable most of the time Asymmetric Multi-Processing (AMP)

Each core is running its own OS

Symmetric Multi-Processing (SMP) One OS is running on multiple cores

Hybrid

S/W is the most sophisticated element and key differentiator

Sometimes, portability of the SW takes priority over efficiency

This Lecture

I want to break this myth, and try to show the other side of Embedded Systems

I will address some of the Industries using Embedded Systems

I Will try to show some new trends, and the motivation for them

What is an Embedded System ?

An embedded system is a computer system embedded in a device with a dedicated function

This is different from the traditional, general purpose computer systems

What is an Embedded System?

It is a computing system that performs a specific task (not a general purpose computer)

A lot of times (but not always), It runs in a restricted resources environment, Power limited (battery operated devices)

Processing/Memory limited

Cost limited (inside the device, and not just a computer for multiple tasks)

Size limited (no space for large heat-sink and a cooling fan)

Display size limited

Most of the time it targets real time objectives, this means, It needs to be fast and efficient

It needs to be predictable (execution time known ahead, and almost constant)

APPLICATIONS OF EMBEDDED SYSTEMS

Hand Held Devices

Smart Phones

Tablets

e-Readers

Robotics

Automotive

Military

Networking Devices

And Other Gadgets

CASE STUDY THE SMART PHONE

Under the Hood.

Simplified Smart Phone Architecture

Responsible for: - Applications - TCP/IP networking - Audio/Video Processing - 2D/3D Graphics

Responsible for ( Communication Stacks) - Cellular (2G/3G/4G) - 802.11 - Bluetooth - NFC - GPS

Android (Linux Based) Windows iOS

Real RTOS: ThreadX Nucleus

TI-OMAP5000 Family

QC-SnapDragon

nvidia- Tegra-4

nvidia-Tegra K1

Conclusions

Smart phones Contain two sets of cores

Communication Processer(s)

Run Communication Stacks (LTE, 802.11,BT,)

Run using RTOS (ThreadX, Nucleus, )

Application Processor(s)

Run the functionality of the phone and any apps on it

Run TCP/IP stack

May contain special cores for Video Processing or 2D/3D Graphics

Use more capable OSs

Most SoCs today have CP and AP on separate chips

The new trend is to combine them in the same chip

Still they run on separate cores/OSs

Different needs

Priority of tasks

CASE STUDY 2 AUTOMOTIVE

Cars Are Getting Smarter

Electronics represents 40% of total cost of a car

90% of new car features require software

Embedded Systems in the Powertrain

Electronic Control Units (ECUs)

ECUs are used in different functions of the car Engine Control Transmission Control Fuel Efficiency Control Electric Power Steering Speed Control Brake Control Suspension System Control Battery Management Seat Control Door Control Electric Windows Control Lighting Control Airbag Control Telemetric Control Mirror Control Security System Control Windshield Blades Control Entertainment Human-machine interface (HMI) And a lot more ..

Proliferation of ECUs Problem

Number of ECUs is going out of control (more than a 100 ECU in todays car)

Cost

Maintenance and diagnostics

Complexity of management

Need of communication among them

Power efficiency

Heat

Portability

Interaction between features

Some software was written for legacy OS

Need to re-test with the addition of every new feature

Time to market

Solution ???

Why not aggregate these functionality into less number of ECUs

A single Embedded Platform with all of the controllers as applications running on top of it

This has some obstacles:

Security concerns

Fault isolation concerns

Some controllers require legacy OSs

Some controllers can not run as an application, requires full attention of the hardware

Different needs some need real time support while others dont

etc.

Embedded System Virtualization

Virtualization What ??

Host Machine

Virtual Machines (VMs)

Virtual Machines Monitor (VMM) Hypervisor

Virtualization Why??

Virtualization is used for:

Running Multiple Operating Systems simultaneously on the host machine

Easier Software Installations for software packages

Testing and Disaster Recovery

Infrastructure Consolidation

Separation between different environment

Fault isolation

Security

Virtualization How ?

We can achieve virtualization via the use of a Hyper-visor

Hyper-Visor is a software that can accommodate multiple virtual machines. Each VM can have its own OS

There are two types of Hyper-visors,

Type One (Bare-Metal Hyper-Visor)

Native Virtualization

Type Two (Use of host OS)

Hosted Virtualization

Virtualization How ?

Hyper-Visor Acts as a light host OS Hyper-Visor Acts as an Application

Native (Bare Metal) Virtualization

Hosted Virtualization

Virtualizing HW Resources

Virtualization in Embedded Systems

Use Cases

RTOS & GPOS Consolidation

RTOS & GPOS Consolidation

Legacy OS Consolidation

Legacy OS Consolidation

Performance-Critical Application Separation

Performance-Critical Application Separation

Trusted/Open Application Integration

Applications of Virtualized Embedded Systems

Applications

Virtualization in Smartphones

Virtualization in Automotive

Virtualization in Automotive

Virtualization in Military Applications

Virtualization in Industrial Automation

Virtualization in Embedded Gaming

Limits of Virtualization

Processing

Extra layer from the hardware

Two level task scheduling

Limits of Virtualization

Processing Extra layer from the hardware

Two level task scheduling

Limited hardware support

Preemption, L2 Cache

Sometimes we dedicate some resources to a certain VM (CPU Affinity)

Memory VMM foot print

Possibly multiple Oss

Resources Resource sharing is tricky

Still a risk of extra bugs due to the VMM layer

Conclusions

Embedded System is becoming more and more sophisticated

Multicore is becoming more common in Embedded systems

Multicore can be using Homogeneous or Heterogeneous cores

The different functions within an embedded system require different needs, such as security, real time, fault isolation

One solution to meet these different needs without the use of multiple embedded systems within the same platform is virtualization

There are still issues to be resolved with virtualized embedded systems

http://Linux4EmbeddedSystems.com