When generating the PCI Express v3.1 rev 1 or PCI Express PIPE v1.3 rev 1 cores using CORE Generator, I find that under the Advanced Link Layer Settings section I cannot select the check box labeled "Automatically calculate timer values (Recommended)". This box is grayed out.
This is expected. Users should not be able to check this box. The text will be changed in the next revision to no longer say that checking this box is "Recommended."