SIMULATION IN HOST-TARGET TESTING
By: Smruti Ranjan Kar
This article describes the importance of simulation in
“host-target testing”. And accordingly leads to a theoretical strategy that
can be followed for the testing of host-target developments.
WHAT IS IT?
Before getting into “host-target testing” first we should
concentrate on the words “host” and “target”. The “host” is the
environment in which the application is developed and “target” is the
environment where the application finally executes. Take the example of
mobile phone games. Are they developed in the mobile? No, they are
developed in the work stations. The environment in which they are
developed and in which they run are completely different. This kind of
development is traditionally being followed for the embedded system
softwares. There the application is developed in a powerful multi-user
environment and ultimately runs in the embedded microprocessor
This kind of development is called “host-target development”
and the associated testing is called “host-target testing” or “cross testing”.
Almost every application development follows cross testing to some extent,
depending upon the difference between the target and the host environment.
This difference ranges from minor differences in configuration to major
differences like in embedded system.
Cross testing has become important these days because it is
very rare that the application is developed in the same environment in which
it is meant to run.
ISSUES INVOLVED IN HOST-TARGET TESTING
Technically all testing should be carried out in the environment where the
application has to finally execute or in the target environment. But there are
issues that influence the testing to be carried out in the target system.
The target for which the application is being developed may not yet
The target environment may be less convenient to work with than the
host. Because a target environment may not have a keyboard,
debugger or even a processor.
A bottleneck may arise for many developers competing for the target
environment to test their work. This may hamper the development
Usually the target and its associated tools like in-circuit emulator
costs many times more than that of the host.
This leads us to the conclusion that most of the testing should be carried out
in the host side. But it has also got some potential problems.
The application may have interface routines that require direct access
to the hardware or software of the target.
The host and target may have potential differences in areas like word
length, significance of bits, data structure etc.
Therefore in the design phase, interface routines should be made
isolated, leaving the rest of the software target independent (Fig:1). Also by
simulating target in the host environment, target dependency in testing can
further be reduced.
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