Dynamic Loading in an Application Specific Embedded Operating System

Traditionally, configuration of operating systems is done statically at compileor link-time, but recently dynamic runtime configuration has become possible. Embedded systems however have constraints, such as limited memory and real-time requirements, that prevent many dynamically configurable operating systems from being used in an embedded system. Dynamic configuration has associated limitations: either execution time overheads, due to complex code structures, or restricted flexibility. However, loading compiled code and linking it immediately at load-time avoids many of these overheads. This paper describes efficient dynamic loading and linking techniques employed as part of the Arena special-purpose operating system to allow embedded systems to be configured by replacing resource managers, such as the process manager. In Arena operating system managers reside in user-level libraries. A general-purpose loadingframework, designed specifically for embedded systems, is introduced and two case-studies are described to show the flexibility of the system. Performance measurements are presented to show that there is no measurable overhead introduced by the dynamic loading framework after the actual installation of a resource manager. This paper describes the results obtained by the work presented as “work in progress” at the 24th IEEE Real-Time Systems Symposium [1].