Given the widespread industry support for both internal and external PCI Express (aka PCIe), it seems that a natural extension of the CASPER architecture would be to provide a PCIe interface to the FPGAs via the RocketIO transceivers. For ROACH, this would require an adapter from the CX4 connector(s) to a "PCIe external" connector. For ROACH2 this would require a "PCIe external" mezzanine board. Obviously there would need to be some changes to the XPS base system as well, including a PCIe core, which will be in silicon (not fabric) in the Virtex 7.
While PCIe is not so switchable/routable as 10 GbE, it does provide a potentially fatter pipe into a computer. This could open up new possibilities such as when combined with NVIDIA's "GPUDirect"... http://developer.nvidia.com/gpudirect If anyone has looked into this at all, please share! Thanks, Dave
