A time-composable operating system for the Patmos processor

Abstract

In the last couple of decades we have witnessed a steady growth in the complexity and widespread of real-time systems. In order to master the rising complexity in the timing behaviour of those systems, rightful attention has been given to the development of time-predictable computer architectures. The Patmos time-predictable microprocessor used in the T-CREST project employs performance-enhancing hardware while keeping the system analyzable. Time composability, at both hardware and software level, is a considerable aid to reducing the integration costs of complex applications. A time-composable operating system, on top of a time-composable processor, facilitates incremental development, which is highly desirable for industry. This paper makes a twofold contribution. First, we present enhancements to the Patmos processor to allow achieving time composability at the operating system level. Second, we extend an existing time-composable operating system, TiCOS, to make best use of advanced Patmos hardware features in the pursuit of time composability.

Patmos: a time-predictable microprocessor

“…TiCOS and POK implement a two-level partitioned scheduler and provide an API according to the ARINC653 standard. Ziccardi ported TiCOS to Patmos [72]. 4 MOSSCA is an operating system for safety-critical applications on manycore processors.…”

“…While exceptions 2 to 15 can be used freely (e.g., by the operating system), exceptions 16 to 32 are attached to external interrupts, triggered by I/O devices. The default configuration of Patmos contains a programmable timer interrupt to support a real-time operating system, such as TiCOS ported to Patmos [72].…”

Design of a time-predictable multicore processor: The T-CREST project

“…T-CREST serves as a platform for real-time architecture research. The TiCOS operating system has been ported to Patmos [20]. TiCOS is a time-predictable operating system that supports the ARINC 653 standard.…”

Support for the logical execution time model on a time-predictable multicore processor

“…The time-composable operating system TiCOS [2] has been ported to Patmos [36]. TiCOS is a light-weight RTOS, which is a fork of the open-source POK project [7].…”