The paper describes architectural enhancements to Xilinx FPGAs that provide better support for the creation of dynamically reconfigurable designs. These are augmented by a new design methodology that uses pre-routed IP cores for communication between static and dynamic modules and permits static designs to route through regions otherwise reserved for dynamic modules. A new CAD tool flow to automate the methodology is also presented. The new tools initially target the Virtex-II, Virtex-II Pro and Virtex-4 families and are derived from Xilinx's commercial CAD tools

Invited Paper: Enhanced Architectures, Design Methodologies and CAD Tools for Dynamic Reconfiguration of Xilinx FPGAs

A self-reconfiguring platform is reported that enables an FPGA to dynamically reconfigure itself under the control of an embedded microprocessor This platform has been implemented on Xilinx Virtex IItm and Virtex II Protm devices The platform’s hardware architecture has been designed to be lightweight Two APIs (Application Program Interface) are described which abstract the low level configuration interface The Xilinx Partial Reconfiguration Toolkit (XPART), the higher level of the two APIs, provides methods for reading and modifying select FPGA resources It also provides support for relocatable partial bitstreams The presented self-reconfiguring platform enables embedded applications to take advantage of dynamic partial reconfiguration without requiring external circuitry

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A Self-reconfiguring Platform

Summary form only given. The handling of an increasing number of automotive comfort functionalities has become a significant problem for the most automobile manufacturers since communication, power consumption, available space and cost become important issues for a growing number of engine control units. Our contribution presents a first approach for a flexible versatile FPGA-based run-time system supporting a resource saving function multiplex.

An FPGA run-time system for dynamical on-demand reconfiguration

Reconfigurable architectures can bring unique capabilities to computational tasks. They offer the performance and energy efficiency of hardware with the flexibility of software. In some domains, they are the only way to achieve the required, real-time performance without fabricating custom integrated circuits. Their functionality can be upgraded and repaired during their operational lifecycle and specialized to the particular instance of a task. We survey the field of reconfigurable computing, providing a guide to the body-of-knowledge accumulated in architecture, compute models, tools, run-time reconfiguration, and applications.

Reconfigurable Computing Architectures

Fine-grain reconfigurable devices suffer from the time needed to load the configuration bitstream. Even for small bitstreams in partially reconfigurable FPGAs this time cannot be neglected. In this article we survey the performance of the factors that contribute to the reconfiguration speed. Then, we study an FPGA-based system architecture and with real experiments we produce a cost model of Partial Reconfiguration (PR). This model is introduced to calculate the expected reconfiguration time and throughput. In order to develop a realistic model we take into account all the physical components that participate in the reconfiguration process. We analyze the parameters that affect the generality of the model and the adjustments needed per system for error-free evaluation. We verify it with real measurements, and then we employ it to evaluate existing systems presented in previous publications. The percentage error of the cost model when comparing its results with the actual values of those publications varies from 36p to 63p, whereas existing works report differences up to two orders of magnitude. Present work enables a user to evaluate PR and decide whether it is suitable for a certain application prior entering the complex PR design flow.

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Performance of partial reconfiguration in FPGA systems: A survey and a cost model

Modular systems implemented on field-programmable gate arrays (FPGAs) can benefit from being able to load and unload modules at run-time, a concept that is of much interest in the research community. Although dynamic partial reconfiguration is possible in Virtex and Spartan series FPGAs, the configuration architecture of these devices is not amenable to modular reconfiguration, a limitation which has relegated research to theoretical or compromised resource allocation models. Two methods for implementing modular reconfiguration in Virtex FPGAs are compared and contrasted. The first method offers simplicity and fast reconfiguration times, but limits the geometry and connectivity of the system. The second method, developed recently, enables modules to be allocated arbitrary areas of the FPGA, bridging the gap between theory and reality and unlocking the latent potential of dynamic reconfiguration. The cost of this advancement is increased reconfiguration time. The second method has been demonstrated in three applications, including the first reported implementation of modular reconfiguration in a Virtex-4 device.

Modular dynamic reconfiguration in Virtex FPGAs

This paper presents a lightweight approach for embedded reconfiguration of Xilinx Virtex II/spl trade/ series FPGAs. A hardware and software infrastructure is reported that enables an FPGA to dynamically reconfigure itself under the control of a soft microprocessor core that is instantiated on the same array. The system provides a highly integrated, lightweight approach to dynamic reconfiguration for embedded systems. It combines the benefits of intelligent control, fast reconfiguration and small overhead.

/pdf/a-lightweight-approach-for-embedded-reconfiguration-of-fpgas-5ax9uxp82a.pdf

A Lightweight Approach for Embedded Reconfiguration of FPGAs

A method of enabling partial reconfiguration in a device having configurable resources is disclosed. The method comprises receiving a configuration bitstream comprising configuration bits; configuring the configurable resources of the device using the configuration bits of the configuration bitstream; receiving a request for a partial reconfiguration of the device; loading updated configuration bits into memory elements associated with a portion of the configurable resources in response to the request for a partial reconfiguration; and providing a status of the partial reconfiguration while loading the updated configuration bits. A circuit for enabling partial reconfiguration in a device having configurable resources is also disclosed.

Methods and circuits enabling dynamic reconfiguration

Method and apparatus for a dynamically reconfigurable, including partially reconfigurable, multi-stage crossbar switch using configurable circuitry is described. Configurable circuitry is configured to provide the multi-stage crossbar switch with at least: a first stage configured from a first portion of the configurable circuitry to provide a first plurality of crossbars; a second stage configured from a second portion of the configurable circuitry to provide a second plurality of crossbars; and a third stage configured from a third portion of the configurable circuitry to provide a third plurality of crossbars. The first stage having inputs, and the third stage having outputs. The inputs and the outputs user selectable for responsive path configurable input-to-output cross-connectivity via the first stage, the second stage and the third stage using the first interconnects and the second interconnects.

Patrick Lysaght

Papers

Invited Paper: Enhanced Architectures, Design Methodologies and CAD Tools for Dynamic Reconfiguration of Xilinx FPGAs

Modular dynamic reconfiguration in Virtex FPGAs

A Lightweight Approach for Embedded Reconfiguration of FPGAs

Methods and circuits enabling dynamic reconfiguration

Reconfigurable multi-stage crossbar