Appendix A: custom eCos configuration¶
ECos is called a configurable system for a reason: it contains a powerful infrastructure for choosing what system components and abstractions are included and how they are configured.
This Appendix will describe briefly how to deal with .ecc files for the Colibri VF61.
Background¶
The main tool used for building the eCos operating system is ecosconfig (see Prerequisites). The source tree of eCos, called eCos repository (like for example the source code tree provided in this release) is not built directly but instead first trimmed down and configured to suit the needs of a specific user and platform using ecosconfig. This static pick-and-build procedure allows the user to exclude these elements of the system which are not necessary, thus reducing the memory footprint. This mechanism also enables easy configuration of system-wide variables and driver specific features.
What exactly can be included, excluded or configured is determined by the contents of .cdl files residing side by side with all source files in the eCos repository (usually in the cdl directory on the same level as the src directory of a given package, like a driver for a particular interface).
configtool¶
configtool is a GUI front-end to ecosconfig to facilitate the creation of eCos configuration files. It also may be downloaded from eCosCentric.
Warning
configtool (just like ecosconfig) is a 32bit application, thus if you are using a 64bit OS you have to provide 32bit run-time libraries for compatibility. In a Debian-based Linux distributions these could be installed using the command sudo apt-get install ia32-libs.
Warning
The official configtool version given above was found not to work on Arch Linux and Fedora Linux distributions. In case of problems, you can try a version from another source or compile your own version.
Templates¶
While creating a new .ecc file it is easier to also use a predefined template representing common use scenarios, such as posix which represents a system which has all the necessary packages to run typical POSIX programs or redboot which understandably is used to build a binary of RedBoot, the eCos bootloader.
In order to select a template to base upon, use .
Warning
Remember that the templates are just general scenarios, which may contain settings incompatible with the desired ones (baudrates, console mangling, debug console choice, presence of RedBoot ROM monitor). It is necessary to tweak them according to your needs.
Preparing an .ecc file using configtool¶
Launch configtool.
Select specify the path to eCos repository (the packages directory).
Select the option and choose the Toradex Colibri VF61 as your hardware platform with default set of packages.
Click continue to proceed.
When the default set of packages is used for the platform, the associated .ecc file can already be prepared.
Save it in a directory accessible by your build script and remember to point to it in the kernel build script.
Other packages can be added from , bear in mind that you may need to alter the chosen packages and options to satisfy some .cdl constraints.
Startup memory choice¶
There are three memories from which eCos software may be launched in Colibri VF61.
This is determined in the .ecc file the eCos kernel was based on.
By default the software is prepared to be launched from OnChip RAM (OCRAM). Alternatively DRAM memory may be used for booting. In this approach however the DDR memory block assigned to Linux must be limited to prevent Linux from accessing the memory region already occupied by eCos. This may be achieved by altering the boot arguments from U-Boot as described in the section entitled Configuring U-Boot.
The OCRAM and DDR scenarios are recommended; alternatively you may also try to run eCos from TCML, but this method was not tested. Besides, TCML offers a limited amount of memory which may be insufficient for many eCos applications.
To modify the startup memory scenario in the eCos kernel, configtool can be used. The appropriate menu option is:
The associated parameters are:
- CYG_HAL_STARTUP_PLF (ByVariant / DRAM)
- CYG_HAL_STARTUP_VAR (OCRAM / TCML)
