v1.8, v1.7.1, v1.6.1, v1.5.2, v1.5.1, v1.5, v1.4, v1.3, v1.2 Known Issues
The link will not train if the received TS1 or TS2 has a bit 6 set of symbol 4, autonomous change bit.
Bit 6 is reserved in the Gen 1 PCI Express specification, but it is used in the Gen 2 specification. Some Gen 2 slots might set this bit, even when communicating with a Gen 1 device. This should be ignored by the device. This problem would only occur in a Gen 2 slot using this bit.
A work around for this issue will be available in v1.9.