eCos is configured to provide the desired API (the inclusion of libc, uitron, and the disabling of certain undesired funtions, etc.), and semantics (selecting scheduler, mutex behavior, etc.). See Chapter 7, Configuring and Building eCos from Source.

It would normally make sense to enable eCos assertion checking at this time as well, to catch as many programming errors during the development phase as possible.

Note that it should not be necessary to spend much time on eCos configuration initially. It may be important to perform fine tuning to reduce the memory footprint and to improve performance later when the product reaches a testable state.

While we strive to thoroughly test eCos, the vast number of configuration permutations mean that the particular configuration parameters used for your project may not have been tested. Therefore, we advise running the eCos tests after the project's eCos configuration has been determined. See Chapter 8, Running an eCos Test Case.

Obviously, this should be repeated if the configuration changes later on in the development process.

While your project is probably targeting a specific architecture and platform, possibly custom hardware, it may be possible to perform part of the application development using simulated or synthetic targets.

There are three good reasons for doing this:

This approach is possible because all targets (including simulators and synthetic ones) provide the same basic API: that is, kernel, libc, libm, uitron, infra, and to some extent, HAL and IO.

Synthetic targets are especially suitable as they allow you to construct simulations of elaborate devices by interaction with the host system, where an IO device API can hide the details from the application. When switching to hardware later in the development cycle, the IO driver is properly implemented.

Simulators can also do this, but it all depends on the design and capabilities of the simulator you use. Some like Bochs provide complete hardware emulation, while others just support enough of the instruction set to run compiled code.

Therefore, select a simulator or synthetic target and use it for as long as possible for application development. That is, configure for the selected target, build eCos, build the application and link with eCos, run and debug. Repeat the latter two steps until you are happy with it.

Obviously, at some time you will have to switch to the intended target hardware, for example when adding target specific feature support, for memory footprint/performance characterization, and for final tuning of eCos and the application.

Repeat the build-run-debug-cycle while performing final tuning and debugging of application. Remember to disable eCos assertion checking if you are testing any performance-related aspects, and to enable compiler optimization (e.g. -O2) it can make a big difference.

It may be useful to switch between this and the previous step repeatedly through the development process; use the simulator/synthetic target for actual development, and use the target hardware to continually check memory footprint and performance. There should be little cost in switching between the two targets when using two separate build trees.