I noticed the GTP users guide makes mention (p. 93) of the RXRECCLKx recovered recieve clock outputs, but immediately recommends against their use in favor of their GTPCLKOUTx copies. All of the illustrations show it this way too.
However the tranceiver code generated in the Ethernet 1000Base-X/SGMII LogiCore (as of v10.5, SGMII or dual enabled) uses the RXRECCLK0 output directly, and leaves GTPCLKOUT0 open. What is the rationale behind this?
Is the core wrong? Or is there an approprite/allowable use for the direct RXCLKOUTx ports? What gives?
Also, I found that the GTPCLKOUTx port must go through a BUFIO2 in order to route to a BUFG, however RXRECCLK can get directly to a BUFG, as is done in the core, and seems easier to use. Instantiated in hardware it seems to be working just fine.