MGT reference clock usage

[spman]

Hi,

How MGTREFCLK should be used? I saw schematic of an Virtex-5 board with PCI Express x4. Two MGTs of the FPGA had been used for PCI Express. But only MGTREFCLK of one of the MGTs had been routed to clock and the other had been left floating and unused!
Does MGT work without using MGTREFCLK? What is the purpose and usage of MGTREFCLK?

Thanks in advance

 

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If you look at the MGT documentation for the V5 you'll see there is a way to route the clock from one MGTREFCLK to other MGTs in adjacent tiles.

Regards