eCos’s configurability is the key to implementing different operating systems as compatibility layers on top of eCos’s kernel, because the semantics of basic kernel functions can be configured to match the semantics of other operating systems.
The specification for the µITRON operating system has been implemented on top of eCos. µITRON is configured by selecting appropriate options in the kernel (a real-time clock, the mlqueue scheduler, and no timeslicing), and writing a thin layer to map the µITRON system calls.
The µITRON port implements the complete µITRON 3.02 “Standard functionality” (level S) specification, as well as some of the “Extended” (level E) functions. The µITRON implementation is described in more detail in the eCos Reference Manual.