What is the size of the RX elastic buffer in Virtex-II Pro MGTs?
The buffer is 64 deep by 13 bits.
The 13 bits include each byte of data (either 8 bits or 10 bits, depending upon the data path size) plus a number of status bits.
The RX elastic buffer goes to half full upon initialization or reset (RXRESET = 1), which is illustrated in the figure below:
The overflow and underflow mark is set when the difference between the read pointer and the write pointer is 12 or less. These cases are illustrated in the figure below:
An overflow or underflow on the RX elastic buffer causes RXBUFSTATUS to go High.