Using Relocatable Bitstreams for Fault Tolerance

The regular structure and addressing scheme for the Virtex-IIfamily of field programmable gate arrays (FPGAs) allows the relocation of partial bitstreams through direct bitstream manipulation. Our bitstream translation program relocates modules on an FPGA by changing the partial bitstream of the module. To take advantage of relocatable modules, three fault tolerant circuit designs are developed and tested. While operating through a fault, these designs provide support for efficient and transparent replacement of the faulty module with a relocated fault-free module. The architecture of the FPGA and static logic significantly constrain the placement of relocatable modules, especially when a microprocessor is placed on the FPGA.