RTEMS 4.5.0 On-Line Library

Directory Structure

RTEMS Development Environment Guide

Chapter 2: Directory Structure

The RTEMS directory structure is designed to meet the following requirements:

encourage development of modular components.
isolate processor and target dependent code, while allowing as much common source code as possible to be shared across multiple processors and targets.
allow multiple RTEMS users to perform simultaneous compilation of RTEMS and its support facilities for different processors and targets.

The resulting directory structure has processor and target dependent source files isolated from generic files. When RTEMS is built, object directories and an install point will be automatically created based upon the target BSP selected. The placement of object files based upon the selected BSP name insures that object files are not mixed across CPUs or targets. This in combination with the make files allows the specific compilation options to be tailored for a particular target board. For example, the efficiency of the memory subsystem for a particular target board may be sensitive to the alignment of data structures, while on another target board with the same processor memory may be very limited. For the first target, the options could specify very strict alignment requirements, while on the second the data structures could be "packed" to conserve memory. It is impossible to achieve this degree of flexibility without providing source code.

RTEMS Development Environment Guide