The PCI Express Base Specification has many optional features. The following features are not supported in the core:
- ASPM L1/L0s is not supported for root port mode
- Resizable BAR extended capability
- ID-based TLP ordering
- TPH capability
- WAKE and CLKREQ are optional signals not supported in the IP
- PCIe beacon transmit and receive is not supported
For more information, see Migrating.