How should unused Rocket I/O transceiver pins be handled?
All Rocket I/O transceivers on the FPGA, whether instantiated in the design or not, must be connected to power and ground (this applies to AVCCAUXTX and AVCCAUXRX and GNDA; VTTX and VTRX need not be connected).
Unused transceivers can be powered by any 2.5V source, and passive filtering is not required. (Please see the "PCB Design Requirements" section of the Rocket I/O User Guide for more details.)
The Tx and Rx pins can be left unconnected. The Rx pins can safely be left unconnected (even in a design that uses the transceivers) without oscillations causing erroneous behavior, as the termination resistors (50 or 75 ohms) will act as pull-ups on the line.