Should Lane0 be used for X1 mode PCIe of C6678?

Hi All:

I learn in the datasheet of C6678 that X1 and X2 mode PCIe are supported, but  the PCIe of C6678 cann't be used

as two X1 PCIe.

In our design, X1 PCIe is used.  Shoud I use lane0 or lane1 for our application?

Thank you very much.